The Cogeneration Stopgap

The prospect of going through a cold winter with inadequate heat is a real one.  More and more Americans are putting their winter heating fuel on credit, increasing their level of debt and the burden of servicing it.  This cannot continue indefinitely.  When the ARM resets or the credit cards max out, the whole house of cards (including paying the mortgage) falls down.  Foreclosure is the problem in the mid-term, but freezing strikes as soon as there's no fuel for the furnace.

This problem is made much worse by fuel shortages and the consequent price spikes.  As fuel supplies go down, prices go up.  The alternative is rationing, but this has costs too; if commerce is shut down, employees don't get paid and the problem of paying for heat is much the same.

The problem comes down to affordability.  Whether there is a limit to the gas available, or if incremental supplies command unaffordable prices, the alternatives are to do more with less, or do without.  As N. American gas supplies are already shrinking, any good solution has to involve getting out in front of the problem and staying there.

So what can we do?

In the end, natural gas will be too expensive to burn just for space heat.  The obvious long-term solution for most areas is a combination of superinsulation and passive solar design; if you need no fuel, you don't care how much it costs.  Does anyone care about the cost of spermaceti anymore?  But that's a 50-year goal; the immediate problems are going to center around keeping existing buildings warm and lit until they are finally renovated or replaced.

If we have a relatively fixed building stock and a declining supply of gas for heat, the problem becomes one of getting the same amount of heat out of less fuel.  The big question is if we can do that, and how?

Can we do it?  I believe the answer is "yes".

Why should you believe me?  Because I see a way for it to be done.  The technologies have been with us for decades, though newer ones will improve the performance.  It's attractive enough that some businesses have been moving this way for years; all we have to do is accelerate the existing trends.

How do we do it?  In the longer term, we replace natural gas with electricity.  But this takes a relatively long time to plan and build generators, transmission lines, and so forth.  In the short term, we do jiu-jitsu with entropy.

The nature of the fix

Getting into the details requires a discussion of entropy.

Entropy is a rather arcane concept, and hard to grasp without at least an introductory course in thermodynamics.  I'm not going to ask that of readers here, or take the time and space for the digression.  I'm just going to ask you to accept three things:

  • That energy is conserved; any energy in a system came from somewhere, and can neither be created ex nihilo nor disappear.
  • That energy in the form of work (turning a shaft, electricity) is more useful than energy as heat.
  • That work can be used to move other energy around in useful ways.  One is to push heat from a lower temperature to a higher temperature.

How does this help fix things?  It helps if I restate the problem.

The nature of the problem

We have a lot of building stock which was constructed with relatively poor insulation and little attention to passive heat gain and thermal mass.  Most of this building stock is heated by burning fuel in an open flame at a couple of thousand degrees F, then diluting the heat down to a comfortable temperature.

This dilution of heat involves an enormous increase in entropy.  Allowing an increase in entropy means throwing away an opportunity to do useful work.  What kind of useful work could we want?  Simple:  we could use some work to push more heat (a lot more) to where it does us some good!  And how do you do that?  A few pictures might help:

Here is house #1.  It needs 45 million BTU of heat per year to stay warm in the winter.  If it is heated by a condensing gas furnace at 90% efficiency1, it will use 50 million BTU/year of gas (and 5 million BTU goes up the chimney).  At near-future prices of perhaps $1.50/therm (100,000 BTU), the gas will cost about $750/year.  As natural gas supplies shrink, the price of natural gas will tend toward parity with the price of oil.  Oil at $100/barrel is roughly $1.70/therm; since natural gas is interchangeable with oil for some purposes, we can expect this to be a price floor relatively soon.

90% efficiency may sound like a lot, but it isn't in this context.  The gas furnace is essentially taking the expensive energy as high-temperature heat and, by diluting it, immediately throwing a great deal of its usefulness away.  We don't have to do this.  What we want to do is take the fuel and extract some of the energy as work; we can use the waste heat for heat, and the work as the muscle for our jiu-jitsu.  Climate Energy even has complete systems for sale; not the exact specifications desired, but proof that it works.

Climate Energy's cogenerator efficiency is our major point of interest.  They claim 18.5 thousand BTU/hr in to get 1.2 kW of electricity out (about 4100 BTU/hr of electricity).  This is a thermal efficiency of about 22%.  Losses come to another 2400 BTU/hr, or about 13%.  The losses are a bit high (probably due to the design), but the efficiency seems about par for an engine of that size.

When the heat demand goes over 12,000 BTU/hr, the Climate Energy system has to fall back to a conventional furnace.  This sacrifices the advantage from cogeneration.  We can improve the system efficiency with two changes:

  1. Making the engine bigger, to supply all heating demand from the engine and reduce heat losses to the cylinder walls.
  2. Using outside air to feed the engine and recover latent heat in the exhaust.
With these changes, we can almost certainly hit 30% thermal efficiency in the cogenerator, and 90% total efficiency2.

Assume that we've got it.  What do we do with it?  Using this in just one house wouldn't help.  Gas demand would go from 50 million BTU/year to 75 million BTU/year per house.  How does this improve matters?

Sharing is caring

The twist comes when we get to houses #2 and #3.  In the process of heating itself, house #1 would generate 22.5 million BTU (6590 kWh) of electricity.  Electricity is energy, but it isn't just some random form of energy; it represents work, which is far more useful than heat.  As a matter of fact, it can be used to push heat from colder temperatures to warmer ones using a heat pump.  The best heat pumps can achieve leverage of 4:1 and more (HSPF of 13.6 or greater).

House #1's cogenerator makes 6590 kWh of electricity, or 22.5 million BTU worth.  House #2 needs 45 million BTU of heat, but its heat pump only needs 11.25 million BTU of electricity (3295 kWh) to supply it.  The surplus passes on to house #3, which is completely heated by the remaining 3295 kWh.  We're now heating three houses on the gas that it formerly took to heat one and a half; given that it would have taken 150 million BTU to heat all three houses using gas furnaces, the net reduction is 50%.  At $1.50/therm, the total cost of heating all three houses is just $1125/year, or $375 each.  The reduced demand for gas will help hold the price of gas down.  If oil goes to $200/bbl and natural gas prices follow suit, gas will cost about $3.45/therm and the combination of cogeneration and heat pumps would save about $2600/year.

I hear you saying "Wait!  You can't make 135 million BTU of heat out of 75 million BTU of gas!"  You're right; there is something missing from this diagram.  The part that isn't shown is the 67.5 million BTU of heat taken from the outdoors by the two heat pumps and pushed indoors, courtesy of the capabilities of energy in the form of work.  Energy is conserved throughout.  Entropy also increases at every step, satisfying the Second Law of Thermodynamics.

What would this cost?  In mass production of several million units per year, I suspect a cogenerator could cost as little as $2500 (this is about what a much more powerful car engine, with 4 times as many cylinders and much more complexity, costs).  A single-cylinder engine making 6 kW of power at 30% efficiency would generate 14 kW (47,800 BTU/hr) of waste heat.  One such engine could replace a small-size furnace.  If the price of natural gas is equivalent to $200/bbl oil, the cogenerator would pay for itself in less than 5 years.

Half a loaf will get you to the store

The final objection, and also valid:  "This only gets us halfway.  Once gas supplies fall below 50% of today's, we're stuck again."

That's true as far as it goes, but nothing happens in isolation:

  • We can get better than 30% efficiency.  Delphi and other companies are working to make solid-oxide fuel cells for automotive use.  These are already achieving efficiencies in the neighborhood of 50%.  At 50% efficiency, one house with a fuel cell can power FOUR houses with heat pumps, and fuel demand falls another 20%.  Even 50% isn't the limit; direct-carbon fuel cells (DCFC's) can turn charcoal into electricity with efficiency as high as 80%.
  • The cogenerator is (remember the title?) a stopgap.  Cogenerators can make up the difference between the rapidly-increasing power needs of heat pumps and the slower increase of other electric generation (esp. renewable generation), the decline of gas supplies and the renovation and replacement of the building stock.  We will probably spend the next 10 years installing engine cogenerators, another 20 years building fuel cell cogenerators to replace worn-out engines, and the last 20 years phasing them all out as the building stock gets updated.

Can we build this many cogenerators?  It looks easy.  The USA currently buys about 17 million light vehicles per year, and 99% of them come with some sort of piston engine.  Many of these engines have 6 or more cylinders, and can produce at least 100 horsepower (75 kilowatts) per engine.  There are roughly 50 million buildings heated with natural gas; converting 10% of them per year would require just 5 million cogenerators.  If each cogenerator has one cylinder producing 6 kW, this is about 5% as many cylinders and less than 2.5% as much power as each year's vehicle fleet.

Other twists

Nothing happens in isolation, and the cogenerator/heat pump scheme would be no exception; it would be intimately connected to the electrical grid, and by extension it would connect to everything else that's plugged in.  The effects snowball, and they're all good:

  1. Any other source of power offsets demand for natural gas; if houses 1-3 have wind power available 30% of the time, about 5900 kWh (1/3 for the heat pumps, 2/3 for a resistance heater to substitute for the cogenerator) would cut gas use by 30%.  If off-peak wind power costs 4¢/kWh, this would use $236 of electricity to displace $338 of natural gas at $1.50/therm.  If natural gas climbs to $3.45/therm, the wind would displace $776 of gas.
  2. Electric vehicles or PHEVs could be charged from the extra generation resource; shortage of electricity would be put off for quite some time.
  3. Adding to #2, displacing petroleum from motor fuel would allow it to be used as heating fuel... in cogenerators, further extending the supply of both heat and electricity.
  4. Adding as much as 300 GW of cogeneration to the grid, most of it within a block of the point of use, would add stability to the grid and slash transmission losses.
  5. Any community with enough cogenerators would be able to operate as an "island" during a winter grid outage, making power interruptions far less troublesome.  Given electric vehicles with V2G capability, these islands could be as small as one house.

As you can see, there are many reasons to start on this path now.


A large part of the USA needs heat in the winter, and much of this is supplied by natural gas.  N. American gas supplies are shrinking rather rapidly, so we must do something about it for both the long and short term.  While we wait for the building stock to turn over, the combination of cogenerating furnaces, heat pumps and other grid-connected devices can shrink our total fuel demand, allow us to make substitutions much more easily and turn big problems into minor inconveniences.  If we want a warm, clean, secure and affordable future, this is a good place to start.

1.  90% is on the low end of efficiency figures for condensing furnaces (which go up to about 97%), but it makes the numbers neater.  The broader conclusions are the same.
2.  These numbers are also chosen to make the arithmetic come out more neatly; small changes make small differences.

Further reading

Ground Source Heat Pumps, by Heading Out.

Really unbelievable, even heating oil is bought by credit. Here in Europe it is just unthinkable.

One has to ask: What kind of goods can you NOT buy by credit?
What about taxes? Can you pay taxes by credit?

What about taxes? Can you pay taxes by credit?

I have not heard of a Gov't that takes credit card directly but since credit cards will let the holder obtain a "cash advance" and many cards now supply you with cheques you can write which clear through to your card balance then the answer is "yes" you could pay taxes by credit card.

California accepts credit cards for personal income tax.

What about taxes? Can you pay taxes by credit?

I have heard that old people in California can have the city put a lien on their house for the value of property taxes instead of paying property taxes. With property taxes of 1% of the house value and "house value" increases of only 2% per year (due to proposition 13), a house just increasing at the rate of inflation shouldn't have too much difficulty maintaining additional yearly liens until the owner dies.

Well, as a matter of fact, the IRS (US Federal Tax Collector) DOES take credit cards, through some officially sanctioned 3rd party providers.

Here is the link:,,id=101316,00.html

Yes, things are a little whacked around here these days. There was an article in this morning's newspaper about 'payday lenders' who take postdated checks as collateral. There is a proposal to limit them to 45% APR. Currently it is over 300%!!!!!!

In the USA, you can buy any goods and services with a credit card. Some smaller businesses require a minimum purchase, such as $10.
I buy nearly everything (but not my heating oil) with a credit card, but pay my bill in full every month, so that I am not carrying a balance or subject to interest charges. Many people are not so conscientious. Average credit card debt continues to rise. It may be the next meltdown.

One has to ask: What kind of goods can you NOT buy by credit?
What about taxes? Can you pay taxes by credit?

It might be a variation on, "They pretend to offer government services, so we pretend to pay our taxes."

(not sure of the relevance to co-generation...)

Chap here who supplies firewood has decided to take cash only as there have been too many problems with cheques. But then again maybe has just made an exception in my case:)

If people are having difficulty paying to operate current heating systems, how will it be possible for them to pay to replace those systems with alternatives? Almost all replacements have an up front cost in excess of expected future savings.

I have long said that once we pass peak, there will be insufficient energy to invest in the infrastructure for any alternative, even if there is an infrastructure that can come close to working. So here we are now, not clearly in production decline yet, and some people are not even able to provide themselves with necessities like heat in the winter. Insufficient energy to fuel our economy means the economic pie shrinks, and adequate heat in the winter is part of that economic pie. Over the span of the oil age we progress from improving living standard to stagnation to conservation to deprivation to death; we are somewhere between stagnation and conservation.

If there are future historians to describe the industrial age it will be noted that we squandered the planet's energy saving account on trinkets with no consideration of reinvesting it in the future.

This winter I have seen for the first time that people in Colorado, USA are beginning to wake up to energy issues, and it is not the cost of gasoline, but rather the cost of natural gas, heating oil and propane. I live in a rural area that is predominantly heated by propane, and in nearly every conversation the $3.00/gal cost comes up. Lots of 'propain' jokes flying around. I have been using propane for 20 years, and in that time the cost has gone from 50 cents to three dollars. Obviously if the price rose to 18.00 a gallon in another twenty the majority of people would be freezing. In a cold January I use 125 gallons, even though I have an efficient passive solar house and keep the thermostat at 62F. I also have a fireplace and a wood pellet stove. Wood pellets at $225 a ton are much more economical than propane.

I have heard the same stories from people in town who use natural gas, and people back east on heating oil. People are really paying attention. Of course, if you don't have the money it is difficult to retrofit new technology, but there are a lot of cheap things that can be done, like weatherstripping, covering windows with plastic, and lowering the thermostat.

It is a shame that all this sub prime stuff occurred for lots of reasons, but one big one I can think of is home energy improvements. If you refinanced to install a GSHP and/or solar thermal system, you can deduct the interest as a home improvement and enjoy the savings right away. Lots of people would rather pay as they go, but some can see the wisdom of some "energy insurance". When these improvements are carried through to the value of the house at resale, they really catch on.

Yes, Henry, we're at the Peak, yet we have significant numbers of people barely getting by. And that's the whole idea. To whatever level one is able to consume, one is to wholeheartedly fulfill that degree of consumption. And we make it easy: simply select the largest house, vehicle, and TV that you can just barely afford. Everybody's doing it - it's the Amerikan way.

We're probably at peak food as well, yet in absolute numbers there have NEVER BEEN more starving people. Peak money, yet billions scraping by.

This is where the cornucopian/futurists fall down. If we can't do it in the best of times, even though we could, why think we'll do it in worse times? I've never seen a reasonable answer to this question.

As things get worse, they'll get worse.

Background: I'm not a cornucopian by any stretch of the imagination, I think we're in for some very big pain (USA in particular, but the whole globe will feel it)

That said, I disagree that just because we can't do it now at peak, that nothing can be done in the future.

Where there is a will there is a way.

Right now, the will is lacking. The pain hasn't gotten bad enough yet for most people. Everyone is just scraping by, with most people believing (misguidedly) that it is just "temporary". That they can pay with a credit card, and that somehow magically things will be good enough later that they can pay it off. But as the pain gets worse and stretches from months to years, more and more people will come to realize it is not temporary - that due to various factors including but not limited to peak oil (e.g. intentional monetary inflation/debt deflation by the gov't), their standard of living has been drastically reduced. This will induce a lot of motivation (that will thing again). That motivation can be used towards bad (like theft, war, etc), but can also be used towards good (like getting politicians in office who will support real solutions to the problem, and figuring out how to address these problems on a local scale).

When motivation is sufficient, it is quite likely that there will be many communities that will come together to figure out solutions to these issues, implementing things just like what the article describes. That doesn't mean things will be good everywhere - there could be whole regions of the globe (and of N. America) where things break down, because people fail to figure out how to work together, instead continuing to see only their own selfish short term interests. But it seems unlikely that this will be universal.

So I suggest to all the doomers that post messages like this, to get out in your local community to promote these kinds of solutions, especially as things get more difficult. You may find that people's receptivity to such ideas drastically change as the reality sinks in as to the world of economic pain we're headed towards. It will also help when the facts of peak oil intervene to convincingly debunk sites like "PeakOilDebunked". It may take time, but it will happen.


BTW - I am eating my own medicine, I have started a local business promoting alternative transportation using electric bikes and sports utility bikes. I am doing this on top of a full time job, and risking my home financially, because I believe it is the best thing I can do to help address the situation.

This is where the cornucopian/futurists fall down. If we can't do it in the best of times, even though we could, why think we'll do it in worse times? I've never seen a reasonable answer to this question.

The 70's were a bleak time and yet towards the end of the decade when the price of oil soared MPG went way up. why can't that happen now with cars or furnances? not everyone is broke, don't overstate your case.

Sorry, john15, but got2surf never said everyone was broke. You did. You made up that straw man argument. Try again. You get a big fat "F" for that one.

than who is the "we" he stated. he should have said "some." again, not everyone is broke. same as we don't buy everything from china and we have record exports. yes there are problems, but don't overstate it. some people are doing good and some people are doing bad at any time. some people will do fine and some people will struggle.

speaking of straw man, who are the futurists/corns who said that things were good? certainly not people like me who know wages have been stagnant for a decade or so and inflation is higher than the CPI numbers.

greyzone- here is another example.

"And we make it easy: simply select the largest house, vehicle, and TV that you can just barely afford. Everybody's doing it - it's the Amerikan way."

everyone's doing it? again, don't overstate your case.

some people are doing good and some people are doing bad at any time. some people will do fine

And my goodness, are there no work houses, are there no prisons? Gee, doesn't anyone have any statistics on the fine increase in housing for the marginalized? You know those bleak houses where everyone who falls by the wayside goes green, institutionally speaking that is? Does the last man standing outside those walls gets to throw away the key and drive off in his Maserati? No need for anyone to worry about miles per gallon then.

The 70's were a bleak time and yet towards the end of the decade when the price of oil soared MPG went way up. why can't that happen now with cars or furnances? not everyone is broke, don't overstate your case.

Interesting, isn't it? To watch a pond drain and see all the little critters in the still deep pools swim about, faster and faster, while at the edge they thrash about and die.

why can't that happen now with cars or furnances?

With 95% efficent pulse furnaces - how much 'waste' do you think exists?

With 95% efficent pulse furnaces - how much 'waste' do you think exists?

RTFP, it's explained above.

Roughly 50% of the "availability" (ability to do work) is wasted with a pulse furnace compared to a reasonable ICE cogenerator.  Compared to SOFC cogenerators, the waste is about 2/3.

not everyone has a new efficient furnace.

I have managed property in Las Vegas for years. They are well maintained properties, however they are now 40 years old. When summer (Vegas's winter) arrives the cost of keeping those apartments (average S.F. 900) rises to almost $400 a month. We have done the simple things like handing out pamplets to turn the temperature up, we have added insulation and changed out a lot of the air conditioners to more efficient units but it gets worse every year. When we ask the owners to consider changing out windows and putting in expensive solar screens most of them simply don't have the money or won't part with the money which is probably the case. They complain about the costs of taxes, property management, maintenance and the cost of a mortgage. All they want to know is when they can raise the rents.

There is no state assistance to help cover the cost of making these units efficient by putting in new windows and doors, solar screens and reinsulating. Most of the owners bought it for a tax dodge and most of them live out of state. They don't see the suffering and they frankly don't give a damn. If someone is 5 days late with the rent they want a 3 day notice to move.

I know of tenants having to make the choice of paying the rent buying food or paying their utility bills or turning off the Air conditioner. If you turn off the A/C it can kill you but I have seen people try and do it. Sometimes I see them sleeping outside on the grass at night (but we are now taking out all of the grass because of the water crises and replacing it with rock).

When people talk about doing all of these wonderful initiatives we need to understand that with the spectre of expensive energy a lot of Americans are about to feel what it's like to be poor. I think our worship of the almighty buck will be a far bigger obstacle to adapting than making strutural changes. Our economy is a model of Reaganomics trickle down.

Consider Las Vegas, "America's ghost capital" if the casinos need anything like an overpass a new plant or siphoning off scarce water resources for Steve Wynn's private 36 hole golf course for high rollors they get it. Poor people recieve little representation or consideration. At the same time the gaming industry pays 6.25% on gaming revenues and any talk of raising that ridiculously low rate is squashed like a bug. The new legitimate face of Las Vegas -International Corporations are far meaner and money grubbing than the mob ever thought of being.
Las Vegas has Little or no social services, and one of the lowest rated education systems in America and has been dubbed "The Misissippi of the West".

The well off in Vegas live behind guard gated communities much like Haiti - so they don't have to see the poor. But Las Vegas is very much like every other city in America - when it comes to taxes even the Democrats are Republicans at heart. If you mention raising a tax even for the most basic necessity it is voted down 99% of the time.

Let's hear comments on how we are going change the way America does business before we start building the infrastructure.

Thanks for noting the perverse incentives at work in situations like rental accomodations.  If there's a solution, it's probably going to involve making the landlord (who keeps any capital improvements) responsible for at least part of the energy costs.

If the legislature wants to fix the perverse incentive of taxes, they can exempt the value of efficiency improvements from taxation.

"If there's a solution, it's probably going to involve making the landlord (who keeps any capital improvements) responsible for at least part of the energy costs."

You need to read what I wrote more carefully. What it means is changing tax codes for everyone not merely making the landlords responsible. There is already depreciation on improvements. When you are looking at capitailization rates of 5 to 6% how does it make economic sense in spending a lot of money in capital improvements. That's why they have slum-lords.

What I'm talking about is a profound change in the way our taxation system works. You can call it redistributation or socialism but in a Peak Oil world "business as usual" will only magnify the inequities between rich and poor.

For 95% of the "middle class" population the poor are invisible. People get worked up when they think about some unwed mother getting welfare but nobody bats an eye at the perverse economic system that rewards KBR and Haliburton or thousands of overfed defense contractors that "keep us safe" not to mention ethanol plants in Iowa.

America's current economic system works as long as it is rolling downhill. When the economy changes and the machine has to function going uphill well...I think it's a real good bet that it will sputter and stall!

So here we are now, not clearly in production decline yet, and some people are not even able to provide themselves with necessities like heat in the winter.

this has more to do with our over-indebted economy and the collapse of the real estate market than having anything to do with peak oil.

50% of people don't have ANY credit card debt so let's keep things in perspective.

That's good to know John. Maybe we can build debtors prisons for all of those fools who got themselves in over their heads.

As a first order of business for this Brave New World I hereby nominate you for warden.

Any seconds?

The word for the day, and every day, in AmeriKar is squander.

What a tremendous opportunity cost that is associated with driving. Seventy-five percent of the oil consumed daily in the USA is for transportation.

We must take definite step to shift the use of oil resources to more essential needs, such as heating homes and essential business establishments.

We need a leader, maybe Obama?, to alert the American people to raise the problem to the forefront of consideration and propose short and long term solutions.

Don't drive unless you absolutely have to...

Given the right structure, it will be possible to finance them.
California leads the way in innovative financing for conservation.

Basically the energy company installs the equipment, the customer benefits from marginally lower prices for the outset, to incentivise them to have the install carried out, but most of the savings are taken by the company to pay for the equipment.

At the payback the customer then gets the full benefit.

This kind of overall system is very common in Sweden but not as micro systems installed in every house but large often biomass burning combined heat and power plants connected to district heating networks.

Slightly more then 50% of the residential and commercial space heating is via district heating and oil use in these systems has recently become almost abandoned in favor of biomass, garbage, large scale heat pumps, natural gas and some coal. Systems that only burn fuel for heat are quickly being replaced by those that also produce electricity.

In parallell with this we have mass installations of ground source heat pumps mostly replacing oil heating and air source heat pumps mostly complementing houses with resistive electric heating.

Natural gas is in use as residential heat but not to a large degree. There are some companies experimenting with (wood) pellet fired micro combined heat and power and small gas turbines burning natural gas and biogas are commercially available but I have no idea if they sell. Lots of sewage works use biogas for heating and some electricity but most of that will probably be upgraded to wehicle fuel. Biogas and natural gas is too valuble to burn for heat or fairly inefficient electricity production when transportation and (chemical) industry can pay more.

Here is a related post discussing the home heating requirements in USA from natural gas and heating oil by state compared to forest resources. The bottom line is we really use a great deal of oil and gas for winter heating, quantities not displacable by wood on anything but a small scale. I didn't write about scaling up heat pumps but that looks like an important silver BB.

I have a couple of comments. First, natural gas powered heat pumps are already commercially available.

Second, residential cogeneration units are available. George Monbiot highlighted this one in his book "Heat" I think.
Most net metering laws in the US specify renewable power however.


Many houses and buildings can be heated using solar thermal energy. You can store the heat in the ground during the summer and release it back in the winter. SOFCs can get more than 50% efficiency in generating electricity from natural gas and the rejected heat can be used to heat and cool the building with absorption cooling.

Wouldn't the placing of the heat from the AC side of a GSHP not just dissipate and be lost? It's not insulated from the rest of the ground.

It depends on the kind of soil. It is best to have a perimeter for the heat store. This is a district heating development in Canada that did an insulated store.

I would think that with further studies done on geothermal systems in homes, the storage efficiency could be quantified. They have been doing geothermal systems for quite a while and data should be available.

It is interesting to note that Whispergen (a domestic stirling electric generator/hot water plant) after spinning its wheels for a few years is now saying they are booked thru to the end of 2009

Whipsergen has always been 'constrained'. When I looked at the +$30,000 diesel units, there was a waiting list. Oh and you had to get 'certified'. The newer $5,000 CHP systems were 'not aviable to mortals' at the time I looked into them.

The core of one of the deployed CHP systems (from my memory - may be wrong) is gone from the web.
From the archive:y

First, natural gas powered heat pumps are already commercially available.

The example from your link is pathetic; a mere 126% AFUE.  We should be able to hit 200% without undue difficulty.

Second, residential cogeneration units are available...

The last time I checked the figures from WhisperTech, the number I got for the efficiency of their Stirling cogenerator was 11%.  This may do for rich people's yachts, but it will do roughly zip for our energy problems.

A free piston 1kW engine is now being made at about 15/week.

Engine-alternator eff. is about 30%, but burner is not too hot (npi).

Important notice in free piston stirlings in March Scientific American. NASA has picked them to replace thermoelectrics, on grounds of much higher efficiency and 15 yr life in space on Pu238.

Free piston lasts and lasts, crank drive stirlings don't. Most people do not make a distinction between the two. BAD mistake. Too bad SciAm made that mistake.

It is a gas company that is distributing these, so a tinfoil hat might fit well. Seems to me though with a 60% efficient combined cycle gas turbine you get to heat four houses rather than three with the same amount of gas even though you discard the waste heat. And, you don't have the noise in a residential area. Noise was also a reason for going with an external Sterling engine for Whispergen I think. Better use of natural gas is definitely a good idea though.


I Forgot noise. free piston engines don't make any noise thenselves, but their burner/blower might. Crank engines make a lot of noise.

with a 60% efficient combined cycle gas turbine you get to heat four houses rather than three with the same amount of gas even though you discard the waste heat.

Not 4, 2.67.  50 mmBTU fuel * .6 plant efficiency * 4 heat pump CoP / 45 mmBTU heat required = 2.67.  You have the additional burden of transmission and distribution from the remote plants; you don't have this with neighborhood grid-tied cogenerators.

you don't have the noise in a residential area.

Air conditioners are often noisy, and they operate during the summer when many would prefer to have their windows open.  A cogenerating furnace will be much less of an issue.

If we apply a 6% penalty for transmission (7% minus local losses) we get about 2.5:1.

That's not far from the 3:1 gain of the base scenario, and relies on pretty well proven & available heat-pumps, and eliminates the need for establishing procedures for "uploading" power to the grid.

It's a good idea, but it might be good to clarify that most of it's gains are achievable without anything new.

Something to note:  the 60% figure quoted for CCGT is usually based on the lower heating value of the natural gas.  The feasible efficiency of a domestic gas heating system, cogenerating or otherwise, is well over 90% of the higher heating value, which includes the latent energy of the water vapor in the exhaust.

The lower heating value is 90% of the higher heating value so it we take Nick's 6% T&D loss and apply a lower heating value then we heat 3.4 houses with the turbine as opposed to three with the cogen set up. The main effect seems to be getting better thermal efficiency at scale as you originally noted. The current limit to scale is the turbine. It wins out despite the other effects. On the other side, one want's to look at the efficiency of delivering gas to a residence compared to delivering it to a power plant I think.


Hi Nick,

Transmission losses account for about 60% and distribution losses about 40% of the 7.2% combined losses in 1995. Since gas plants tend to be smaller and in town connected to the gas pipeline, we should probably count less of the 4.3% transmission loss against them but fully count the 2.9% distribution loss. Your estimate of knocking off a percent is in the right direction though. At 6% loss, we heat 3.67 houses rather than 3 with the same (75 mmBTU) gas use.


The way I figured it, you were getting enough electricity for two houses at 30% efficient so you ought to get enough for four houses at 60% efficient. I was also comparing your input equally (75 mmBTU, not 50) so that would be 75/50*2.67=4. I did not include transmission and distribution losses. The new gas generator going in here is about 15 miles up the road, but it looks like it is going to be a peaking plant. We did see the new coal plant stopped.

I think it should be possible to make the generator quieter than the heat pumps.



I assume by efficiency you actually mean electrical generation percentage, since the overall efficiency of the whispergen unit is 90%, This is an interesting paper

Micro Combined Heat & Power

And it outlines some of the difficulties of co-op CHP (not directly) but implies that to much microgen power could be a bad thing, Still engineering a 1kW generator that runs on gas and is quiet enough to sit in your kitchen is a start, Fig 2 shows that only 15% of domestic energy consumption is non-thermal (I assume this is in the UK), So there is little point in changing the ratio (Elect/Heat) as gross export of low voltage back into the network could also cause issues (tho I think they are optimistic on this count as the gas will probably run out)


I assume by efficiency you actually mean electrical generation percentage

Yes, I do.  The multiplier effect relies on the electrical generation efficiency, otherwise you might as well be burning fuel in a flame.

And it outlines some of the difficulties of co-op CHP (not directly) but implies that to much microgen power could be a bad thing

"Too much" being enough to make the buildings into net producers, I suppose.  This is not a problem if the cogeneration is balanced with heat pumps to maintain the balance.  It may be desirable to build in a surplus of generation to charge electric vehicles when other supplies are low; when e.g. wind was good, you'd use that for heat and vehicle charging and back the cogenerator duty cycles off.

One thing I didn't detail above:  with a substantial amount of V2G capacity and cogenerators, loss of a line or large generator could be balanced by power from the vehicles for a few seconds, while the cogenerators started and began feeding the grid.  Not even ice storms could take out your power.

Fig 2 shows that only 15% of domestic energy consumption is non-thermal

Which misses the point; by using electricity (work) to run heat pumps to concentrate thermal energy, the total amount of fuel required can be cut in half to start and further offset using e.g. wind energy.  By creating efficiencies and substitutions, the pain of declining fuel supplies can be greatly reduced.


Basically you are using the COP of a heat pump as an efficiency increaser, at a 15/85 elec/thermal split in a UK home (based on that document, I'm in NZ) then you could achieve the same effect with a micro CHP/heatpump, ie if you got a 30/70 split and then used the extra 15% to run a heat pump at a COP of 3 then your net energy output would approach 130%, This could be achieved with a beta style stirling engine. You must admit that considering the regulatory and market impediments that whispertech have had to overcome (ie "How do we do this, what! allow a home to generate power, they are a consumer for godsake!" and "Will it work") they have cracked open the door, I think your crack about luxury yachts was disingenuous. ICE based CHP's are noisy, expensive to maintain and would only get a 30/70 split.

Neven MacEwan E.E E&E

The statements made in that cited paper are way out of date. The free piston machines hve high efficiency and very long life as proven by their choice by NASA for long space missions. See current Sci Am. article on space power stirlings.

As the situation continues to decay I'd be surprised if there was not a reversion to coal for residential heating. This could be in the form of coal or coke solid fuel burning furnaces, or Syngas burning equipment. Bad for climate change, but next years winter will trump next generations children I suspect :<

I read some time ago that using an engine to generate your own power requires a relatively large (3+ liter) slow turning (< 1500 rpm) engine for it to have an acceptable lifespan. Our junkyards are full of the right size engines for a fraction of the cost of new engines. Converting these engines to nat gas or propane is not that big of a problem. What is a problem is the supply of alternators of 6 kw+ and the electronic controls if it is going to be connected to the grid. With the projected increase in hybrid and BEV production competition for these devices will be furious. If a system is not connected to the grid auto cruise control from the same junkyards as the engines could be used for voltage and frequency regulation.
I have long wondered if it made economic sense to build a housing development of say 100 buildings with its own cogeneration system. The electronic controls for a 6 150 kw generators is probably cheaper than it is for 100 6 kw units. Why six generators? 4 units provide power, one unit is for backup, and one unit is down for maintance. Diesel engines of this size are regularly manufactured. Sharing of a CHP system of this size opens up the possibility of a central absortion cooler that could use the engines' waste heat for summer cooling.

"What is a problem is the supply of alternators of 6 kw+ and the electronic controls if it is going to be connected to the grid."

If you don't want to connect it to the grid, and will use all the work on a heat pump, you need no alternators nor electronic controls. You simply mechanicaly tie the engine to the heat pump.

That even trows away some (very minor, but still existent) waste from converting mechanical work -> eletricity -> mechanical work.

One could also toss on a "wet exhaust" system off a boat to pull the heat out of the exhaust and use in a number of ways.

The advantage to using smaller units, yet diesel, and more of them is the waste heat from the engine could privide hot water in the summer. This especially applies to buildings that contain restaurants, pubs, and other establishments requiring good amounts of hot water.

Thanks for your support: (science)

Foreclosure is the problem in the mid-term, but freezing strikes as soon as there's no fuel for the furnace.

for those who can't make their mortgage problems all other expenses are tough. oil doesn't have much to do with it when you're paying a mortgage that's 60% of your pay or more. when they go through foreclosure they will rent or buy another home at a price that is a traditional 30% of their pay. then they can easily heat their home.

I have another thought about foreclosure. In my area, many homes are just being abandoned with the former owners getting an apt or moving in with family or friends. If they turn off the heater and freezing weather comes, the house could be destroyed by burst water pipes. I'm in CA now where this won't tend to happen, but used to live in MN, where it could happen easily and in one cold day.

Hi All,
So this story was quite exciting for me. My father is actually the technology director & co/founder of Climate Energy. I emailed him for his thoughts on the article and I thought I would pass along to you his paraphrased thoughts:
The author would probably be happy to know that the free-watt engine generator is really 92% efficient and does condense vapor from the flue gases. We report the lower number only because the cabinet is ventilated, and if this ventilation air is not usable (located in a non-heated space) this heated air would be a loss. Also, if the unit were bigger it would not make any more useful power because it would make more than the home consumes and you don’t get much credit for the excess production in the current system. It would also cost a lot more which is a very real problem.

Thanks for the article, hope that clears up some things a bit.

I was wrong, it's here. it's here! olduvai gorge in America!

Massive Power Outage Reported In South Fla.

I'm not saying that this isn't a serious problem though. apparently even a nuclear plant lost power but everything is fine.

If we shift from gas heat to electrical heat, even if efficient, we need to consider the adequacy of the electrical supply for the new usage.

My guess is electricity will be a problem sooner than most people are expecting (10 years?). Electrical production will not keep up with need, and grid maintenance will be a problem also. While good planning could better match supply and demand, it seems likely that too little action will be taken. Eventually, planned and unplanned electrical outages will be a frequent occurrence in many parts of the country - similar to what we are starting to see in some of the less developed countries.

For the same reason, inertia and poor planning, gas will likely continue to play a major role in home heating, hopefully a bit more efficiently as EP suggests.

So in practice however much I might advocate it electricity will not take over entirely heating houses any time soon, so that will to some degree mitigate grid problems.

Whatever solutions you come up with though you will need a decent grid.

Solar energy where that is generated at the home may also reduce loads, as it would be generated at the point of use.

In my view however it is unlikely to be a really significant player within the next ten years, although at least for peak load in the south west it could rapidly develop to major importance starting at the back-end of this time-frame.

Other renewables such as massive solar farms or wind power make hugely higher demands on the grid than nuclear, as they would need to transport power far larger distances to where it is needed or to help balance intermittency.

In addition, nuclear power could be used at the low off peak rate to charge electric vehicles, maximising the use of the gird at the least cost.

How would you know when the best time to charge your car from wind power was, as it could maximise at peak, off peak or any other time?

Dave, In the South air source heat pumps can become the norm within 20 years given a little push by electric companies. No added capacity is required. Summer peak capacity plants can be used during winter too. Since almost every home in the South already has central AC, this will mainly be a matter of modifying the AC system, The electrical companies will like it because it would involve year round use of generating capacities once only used in the summer.

If most of the peak load in the South is covered by solar as I expect then that would be an excellent fit to a heat pump, keeping overall system costs down.

Further north tough don't discount air-heat pumps - the latest CO2 ones in Japan are good for down to -15C and one Canadian company does one good for down to -30.

I won't reference them here as they have been extensively referenced in other threads - check out chats I have had here with HereinHalifax.

Everyone in North America will be able to get the benefit of heat pumps without the expense of ground source within a couple of years.

I won't reference them here as they have been extensively referenced in other threads - check out chats I have had here with HereinHalifax.

This does nothing to help those of us who either weren't reading those threads, or don't have time to dig the links from them.

No problem - all you had to do was ask- I didn't want to bore anyone if they weren't interested

Here is Japan's horribly named Eco-cute:

And here the Canadian offering:
Hallowell International: Technical Data

This pdf might help too, although it is a couple of years old:
Technology and Market Development of CO Heat Pump Water Heaters ...

here is the thread where HereInHalifax makes a number of valuable comments on residential heating:

Hope this helps - all this means that for the first time those who live in harsher climates will be able to get the benefits of heat pump technology whilst avoiding the high costs of ground source - pretty transformational, I feel.

And here the Canadian offering:
Hallowell International: Technical Data

Hi Dave,

Just so that we don't panic the fine folks in the great state of Maine, your state has not been annexed by Canada. Rest assured, dear friends, you won't have to add needless vowels to various words, measure your tyre pressure in kiloPascals or end every other sentence with the word "eh?". Oh, special thanks to Bangor, Maine for Stacey's Country Jamboree. We love you, Stacey!


No added capacity is required.

All the capacity in the world is useless if you have no fuel.

"How would you know when the best time to charge your car from wind power was, as it could maximise at peak, off peak or any other time?"

That's easy. Just use a smart-meter, which receives info about power pricing, together with a charger that communicates with it.


Sure, but that is pretty cumbersome as against just plugging your car in overnight when rates are low as you would with nuclear.

If you were at work you might not be able to plug your car in anyway.

" that is pretty cumbersome as against just plugging your car in overnight when rates are low as you would with nuclear."

Well, heck, that's what we can do for the next 10 years for wind, as well. The main problem for wind is the same as for nuclear, that it's output at night isn't needed very much. Charging at night works very nicely for both wind and nuclear. OTOH, time-of-day/smart meters are a good idea in any case, and all US utilities are moving towards them (by federal mandate).

"If you were at work you might not be able to plug your car in anyway."

Again, this is a long-term problem, after we've built a lot of wind (or nuclear). OTOH, it's easy enough to put chargers in parking structures and parking meters. It's done in Canada and Minnesota now, for engine heaters.

In 10 years given the current rate of advances in computer technology, cars will be able to plug themselves in for the night, and unplug themselves in the morning!

Considering it has been in the high 80's and 90's this past week I'm wondering if there was a lot more demand on the grid due to increased AC use. Even though we are used to power outages in these parts usually due to hurricanes, just the chaos that ensues from the traffic accidents caused by traffic light outages at major intersections is a major burden on emergency responders. This blackout I'm sure is no exception. I have never understood why for example,our traffic lights don't have solar powered battery backups for such emergencies?

In the late 1960's and early 1970's my father investigated the health effects of stimulating natural gas production by using nuclear explosions. He concluded that the health effects from radiation would would be minimal, but natural gas could better be used as feed stock for industry. Given a limited supply of natural gas it was more rational to heat with electricity, and save the gas for uses that would add greater economic value to the economy. This is called making wise choices.

Heating in a rational economic world can be handled 2 ways. First through electricity. The second is through renewable energy sources. Biomass approaches are messy and unhealthy. Burning organic material is a good way to create air pollution. I highly recommend that we move away from any fossil fuel source as soon as possible.
Urban wind use is impractical. Most PV's use the grid anyway. Cogeneration still produces CO2. Over time fuel for cogeneration will get more expensive, and will incur carbon penalties as well. Wide spread us of fossil fuel co-generators will contribute to air pollution problems. Even with sophisticated pollution controls, the co-generators will produce fine particulate emissions.

Electricity is more efficiently used with heat pumps, than with resistance heating. Air source heat pumps are now very efficient. Air conditioners are one way heat pumps. It would not be that expensive for air conditioner manufacturers to convert their product line to add heating.

Ground source heat pumps are more efficient, but are much more expensive to install and maintenance problems can be very expensive to solve. Solar water heaters, represent a mature technology, and there are some advantages to electrical utilities to subsidize their installation, with secondary electrical backup.

Solar space heating may have some advantages in the Southwest.

With solar space heating we can save enough natural gas to run our cars. It would require an investment to convert cars to dual fuel and install the solar thermal collectors, geothermal bore holes and heat pumps, but you are trading hardware for efficiency. Running cars on natural gas would be much cleaner and reduce our oil imports.

Yep, I don't think we should be thinking in terms of using natural gas to heat our homes, conservation, insulation, passive heating, nuclear electricity and the new air heat pumps good for down to -15C are the way to go, with natural gas as a transport fuel if we absolutely have to or preferably just a feedstock for industry - it really doesn't make sense to build in a natural gas burn to heat our homes.

It all depends upon your perspective.
Fueling cars with nat gas is easy to do - but a total waste. I commute by bicycle but could easily switch to city bus. If finances get tight the first thing to go is the car - and we would not really miss it. I'd love an EV for in town stuff - and then rent for vacations; but it's not viable - the cost of purchase and insurance is the major cost of a car - NOT FUEL (for us anyway). For the home the major expense is taxes - at >3x the total energy cost of the home.
Ground source heatpumps are neat - but spending $15k for a heating system when it costs $350/yr in nat. gas is kind of insane. High-eff gas furnaces are also electricity hogs. I'd suggest going with a mid efficiency instead and piping it's flue gases thru a HRV. That was discussed back in '91 as you then get the efficiency of a high-eff condensing furnace without the cost of the combustion air motor. In our home the furnace uses around 60% of our total electrical bill. It's rather stunning - but then our normal elec bill is $15 to $20/month (5 kWh/day in the summer and 8kWh/day winter) and the furnace we bought is a York GY9 - AC blower motor - but the DC motor would only save us about $6/yr.

As for passive solar - I wish. My calculations (The Passive Solar House - Kachadorian) gives a peak of about 28% of our total heating from the sun. It's pretty cloudy in southern Ontario and to hit 28% one would have to run around putting styrofoam over the outside or inside of most windows every night! Otherwise TiR Low-E windows would peak at perhaps 20% of total heating needs without having to use thermal shutters.

It's so much easier to do without than it is to chase fancy techo-dreams like ground source heat pumps. I'm keeping my ears open for developments on aerogels though.

I'd love an EV for in town stuff - and then rent for vacations; but it's not viable - the cost of purchase and insurance is the major cost of a car - NOT FUEL

most electric cars or PHEVs don't seem to be that much more expensive and as they get widely adopted they will be even less expensive.

"Urban wind use is impractical"

I would not make blanket statements like this. In the upper midwest, where a huge amount of nat. gas is used to heat, the wind tends to blow especially hard in the winter time. Check out the weather in Fargo, North Dakota (240 miles from Minneapolis), and you will see that the wind is nearly always blowing. Really cold days tend to have higher wind speeds. Same is true for many places in Iowa, Nebraska, Kansas and South Dakota.

Wind is practical electrical power for the western part of the midwest. It could easily be supplemented by diesel powered co-generation that runs partly on biofuel and also powered by PV. And as you point out passive/active solar should be a big part of heating.

These guys have a design that could go on top of a lot of big box stores.

A lot of electricity comes from natural gas turbines, so if you can generate it locally, that is less natural gas used at the power plants.

Here is a study or how wind tracks demand for the UK.

As you can see, it is around two and a half times more powerful in the winter than in midsummer.

Obviously this will vary with the area, but it sounds as though it is good in the area you mention.

That is not so great though if you need air conditioning in the summer, as it won't help much there, assuming it has a similar pattern to the UK.

I also find it difficult to envision a situation where you wouldn't be better off sticking a couple of big turbines really high up outside the city and using that power.

Turbines hate ground effects, like size and height and can cause unwelcome vibration and damage when directly attached to a building.

In locations like London roof turbines are simply vastly expensive eco-bling.

Construction in the northern plains needs a whole new paradigm. We keep recylcing old ideas that are inappropriate for the PPOG world people will be living in.

Obviously, mitigating the effects of the cold winter winds are the first challenge. Combining one or more of the follow ideas should produce much better results than we are now getting.

1) Make sure new construction starts well below grade. To the extent that this can be accomplished, less is exposed to wind.

2)Use "rounded" roof construction that lets wind slip by without producing eddy wake vortices, which cause pressure fluctuations and exchange of air with indoor. A housing "wing" would consist of a dozen or more townhouses covered by a long (upside-down) U-shaped roof, oriented longitudinally to the prevailing winter wind. I think Native Americans used this concept for their "Longhouses". (CMIImW)

3) Construct bike/scooter paths below grade(4 ft.?)and covered with similar rounded roofs. The the excavated dirt could be bermed alongside the path, giving an extra 2 feet of protection.

4) Construct commercial centers (if any are ever built again) with a similar design, additionally having narrow guage rail along the center to ferry people from one end to the other (works for Disneyland!)

5) Build above units for passive heating, to be stored in the summer for winter use (Google Drake, Alberta) or in warm places for maximum reflection of solar radiation.

6) Maximize wind electricity generation, using either horizontal (winter) or vertical (summer) winds.

I like the design concepts there and would appreciate any links.

I'm not quite understanding the distinction you are making by calling the summer winds vertical?

Except for the "vertical winds" a link for which I will provide below, I have no links to provide for the other topics/ideas. It just seems like "common sense" (at least to an engineer).

I suggest you Google "undergroud dwellings" for information on that. These are not new and not that much more expensive. It's not done much because people like to point at their houses and say to others: "see, I've got mine--isn't it beautiful" (prancing horse syndrome).

As far as wind producing air infiltration, it's a well known fact that a "bluff object" in an airstream sheds vortices (Von Karmann) as the air flows past, causing pressure fluctations that would tend to suck air in and out of a building, as well as produce a difference in pressure between the upstream and downstream sides of the building. Rounded corners can reduce the intensity, or in some cases, eliminating the phenomenon altogethe when combined with a plane surface. Bike racers use a helmet which is tapered toward the back to eliminate these vortices and thereby, reduce drag

I would welcome underground or bermed bike paths with a cover for personal reasons. There's nothing more unpleasant than riding a bike in the wind or cold weather. I think more people would be attracted to it if they didn't have to contend with the elements. You could even have jitneys or "trains" use the systme to transport people who can't ride bikes.

The most important item is the harvesting "vertical winds" or updrafts that tranport about half the energy that is ultimatley radiated back to space from the surface of the earth to the mid troposphere. They result from "Convective Available Potential Energy", which measured the degree to the which the troposphere contains "cold air over warm air" a measure of the instability of the atmosphere, more available in the NH during the summer when there is plenty of insolation.

A machine to harvest these updrafts before they "break loose" has been developed and patented by AVEtec, of Sarnia, Ontario Canada. (Inventor--L.M. Michaud--The Wizard of On). AVEtec is currently soliciting partners to participate in the development. see and read the FAQs where these "vertical winds" are described in more detail.

OK - wasn't sure if there was a school of architecture looking at these ideas - certainly the greenroof design is very important here in Europe but does not usually round off the structures.You might be interested in these structures, but construction costs look high to me:

It would probably be cheaper to make the basic structure rectangular and just put curves on the roof to reduce heat loss.

That is good if you don't have heavy snow falls in your area and need a steep pitch to shed the snow - in Sweden the greenroofs tend to have a steep pitch, but alternatively you could reduce the pitch and shovel off as needed.

I'm talking about barren, wind-swept plains here, where the snowfall is dry and blowing, not the wet snow you might find in secluded mountain valleys or even cities in Sweden.

Geodesic domes have been deployed by the military in these types of locations to protect radar equipment. Apparently, nobody has to shovel snows off these installations.

In this case, what I'm proposing is a "long tunnel" partially below grade, with an arched, possibly transluscent, ceiling/roof. The ends would be rounded and the tunnel divided with separations to form separate residences with their own "step-down" or igloo-type entrances. Again, they could either be aligned with the prevailing cold wind to minimize frontal area, or, if built crosswind, have the windward side built up with berms to cause the airflow to lift over them.

Urban wind use is impractical.

Wind farms can be located outside of town, or even a thousand miles away (China is building a 1300-mile HVDC line with just 7% losses).  The bonus is the ability to use electricity from any source (especially intermittent ones) to offset fuel demand; the bonus from domestic cogeneration is the high degree of flexibility and resilience it would produce.

Cogeneration still produces CO2. Over time fuel for cogeneration will get more expensive, and will incur carbon penalties as well.

Quite true, which is why a 50% savings over standard furnaces, with the potential for 65% savings with added wind power and 72% using SOFCs instead of ICEs, is of such great benefit.

The issue you did not include is the production of twice as many ground source heat pumps as cogenerating furnaces. That's a real problem to scale up as there is not enough drilling rigs around to install that many per year. Most people's homes/buildings will require verticle drilling as they would not have enough horizontal land for shallow depth pipes. And the costs, it's $20K+ per house.

That said, get your's done ASAP before there is a rush!

This sounds a little 'icky', but what about the idea of running a ground loop through a septic tank? It is already buried, and the bacterial action and often hot water going down the drain keeps the temp of the interior of a septic tank quite high, I am told.......

As long as the ground loop is a closed system, what is the downside? The loop could be molded into the tank walls.

'Crap' (ha), someone beat me to it.

Biothermal and geothermal heat exchange apparatus for a ground source heat pump

United States Patent 5730208

Carbon dioxide air pumps can do the job darn near as well as ground source, and without the hassle and at a fraction of the cost.

There are micro CHP systems on the market. Whispergen combines a stirling engine gas fired system to produce electricity with the waste heat being used for domestic hot water. Output is about 1kW and is fed back into the grid if not being used.

A smart idea would be also to recover the heat from the hot waste water from the shower using a heat pump as this is around 30C rather than ground water at 12C. One can heat the incoming cold water to the shower hence minimise the use of materials..pipe runs etc. Basically the system would recycle the heat thrown away down the drain for a small cost.

There are micro CHP systems on the market. - kiwi11 Yet another dreamer wanting to solve problems with solutions that 80% of home owners cannot afford. It would compound the unreality to imagine that most homeowners could afford a water source heat pump that would recover energy from showers.

Not only unaffordable, ridiculously inefficient.  From WhisperGen's documentation:


Electrical: Up to 1000W @ 230VAC, Thermal: heat output from 7.5-12kW

Even assuming zero losses, the electrical efficiency is 1/8.5 or 11.7% at best (7.7% if you assume 1000 W electrical, 12 kW thermal, zero losses).

The extra heat output above 7.5kW is provided by a burner that does not heat the engine. It is for cold days when even more heat than power is needed. You get a similar thing with heat pumps that have heating coils for cold weather. The idea is to not put any power out to the grid but cover some domestic needs. It makes sense if you can save a little on electric rates. And, if you use the electricity in the house, you get all the heat back so you don't use any more gas in a sense. Of course, if you run your toaster from the grid, you use less gas for heat. Monbiot likes it because it avoids some coal use.


Everything created by humans begins with a concept, a dream... There are plenty of heat recovery systems on the market for shower waste water without the use of a heat pump. Though these are only about 30% efficient. Retail for about $500 payback time 18 months depending on usage.

A heat pump is a cheap, simple device to manufacture. I'm working on a DHW heat pump system which eliminates the need for hot water storage, recycles waste water heat and will cost the same as a fridge freezer - most households have one of these types of heat pumps.
Air source DHW heat pump systems are cheap and common, but involve the added expense of storage. This one doesn't need that storage. If one needs a lot of water without reusing the heat eg to take a bath rather than a shower, the system will use the ground source heat store that the house has access to... the existing water pipework to the house. Sure you have to throw a bit of ice cold water down the drain, but that's a fraction of the cost of the heat gained.

Dreamers are also called visionaries. Better than sticking your head in the sand.

Recover "waste" heat from water draining from shower, using a passive device with no moving parts:

I've had one of these for several years, along with an on-demand tankless water heater (burns propane). I found that it introduced a positive feedback that amplified the temperature fluctuations as the flame in the heater turns on and off. That made showering unpleasant. I solved that by adding a small (4-gallon, 15-liter) insulated tank in the output pipe of the heater, to dampen the temperature fluctuations. (That added tank has a heating element but that is not used, never plugged in. But the tank leaked after a few years, had to replace it...) Other than that issue, works nicely. I don't have real measurements of the heat recovery, but by touch I can tell that the cold water entering the coil pipe at the bottom exits much warmer at the top. I also can report very low propane use in the summer...

Alas, the cost of these gizmos (made of pure copper) tripled in the last few years.

Again - it's very easy to do without techo dreams like this.
We use an (oversized) 19 gallon water heater. At $20/year to keep the tank hot and less than $55/year heating water we don't make enough waste heat to power anything. Heat recovery from the water is a non-possibility due to the fact that hot water use is dislocated in time. Ie we only ever use hot water for:
1) shower in the morning or after work, bath for the kids now and then
2) washing dishes in the evening

I can take a shower in around 5L of water - about 1.25 gallons. There simply isn't enough waste hot water to do anything with. I also don't take boiling hot showers nor do I wash dishes with the water set to sterilize - so the waste heat is low grade.

Again - it's very very easy to use less of something than it is to consume like hell and try to live off of the waste of consumption.

1) Reduce
2) Reuse
3) Recycle

Recycling waste heat is the very last step, after one has reduced consumption and reused the gray water in other ways and recycling such waste heat isn't really worth it except in apartment buildings. It's a techno dream that will implode when people don't have the option of wasting hot water excessively.

I hear you saying "Wait! You can't make 135 million BTU of heat out of 75 million BTU of gas!" You're right; there is something missing from this diagram. The part that isn't shown is the 67.5 million BTU of heat taken from the outdoors by the two heat pumps and pushed indoors, courtesy of the capabilities of energy in the form of work. Energy is conserved throughout. Entropy also increases at every step, satisfying the Second Law of Thermodynamics.

Heat from the outdoors?

Do you mean taking the cool from the outdoors heating it from the process of running the engine and then pushing that now warm indoors?

How much noise would these engines make in a suburb? I imagine a lot of effort going into making them super quiet it can be done but would add to any cost and maintenance.

Do you mean taking the cool from the outdoors heating it from the process of running the engine and then pushing that now warm indoors?

No.  I mean evaporating a refrigerant in a tube heated by the earth (most efficient) or outside air, pumping this cold vapor up to high pressure with an electrically-driven pump, and then condensing the vapor to recover its heat at a much higher temperature.

This heat-pump process is separate from the cogenerator.

How much noise would these engines make in a suburb?

Noise represents lost energy.  Honda makes some very quiet generators, and I have no doubt that a low-speed engine in the 6-10 kW range could be designed for both high efficiency and very low noise.  The energy of expansion from the exhaust gases which comes out as noise can, in principle, be recovered as useful work.

I imagine a lot of effort going into making them super quiet it can be done but would add to any cost and maintenance.

That would probably depend on the design.  A second expansion cylinder wouldn't be substantially more complex (it would need only one more valve) and would not be highly stressed.

The engine is indeed extremely quiet. I don't know the dB rating but its almost inaudible at 15 feet. Could be run in almost any household setting with minimal attention being drawn to it.

The ground loops I've seen are too big for average suburban back yards, especially ones already paved over. This might require several neighbours to co-operate. There are too many uncertainties with claiming a five year payback or whatever. Early adopters have to create the economies of scale; no pioneers no economies. Fuel cell based CHP systems look prohibitive; didn't a Japanese guy pay half a million?

I wonder if people could create warm zones in their homes using heavy drapes on sliding tracks. That plus blocking vents of centralised systems.

Since this started with a discussion of entropy, the following site might be of interest to some.
As soon as there is sufficient understanding that this is an emergency, It might be possible to bring back the 55mph speed limit.

Ground loops are easy in suburban backyards. You just drill vertically....

Of course you could create a 'warm zone'. Its called a canopy bed. You have to be careful to vent the carbon dioxide out and let fresh air in if you put heavy curtains on one.

Vertical does reduce yard space but increases pumping costs, but is a good compromise. I read that if you put a vertical bore hole every 10 feet you can get good coverage. The depth depends on the soil and other factors, but less deep would be better for costs. This is still an expensive proposition and natural gas would have to rise in price quite a bit to make it make sense in a milder climate.

Only slightly off topic.

How can we reverse entropy?

The Last Question by Isaac Asimov © 1956

"The energy of the sun was stored, converted, and utilized directly on a planet-wide scale. All Earth turned off its burning coal, its fissioning uranium, and flipped the switch that connected all of it to a small station, one mile in diameter, circling the Earth at half the distance of the Moon. All Earth ran by invisible beams of sunpower."

Asimov didn't understand net energy, and the race between depletion and technology now has 6.7 billion on the side of depletion.

The Asimov link was to a science fiction story and should not be taken too literally. Asimov was one of the earliest and best on population. If there was one person who claim closest to knowing everything it was Asimov. I suspect that he understood net energy even before it was formally published??

"Asimov didn't understand net energy"

What do you mean? Is your point that such a power satellite would take a lot of energy to build? I think that would depend on the time frames involved. In Asimov's story this was pretty far in the future, and used artificial intelligence heavily - self-building solar powered equipment on the moon could build such a thing, with no ongoing terrestrial inputs. It would take a little while...

What are the copper requirements for building this many small electrical generators? Is this going to mean consuming a meaningful amount of copper? If so, where will we get the metal?

For making electrical power you would want to use alternators (AC power) which are smaller and more efficient than DC generators. I think old automobile alternators recycled could provide some of this copper. Second, we must quit shipping so much scrap copper to China - put an export tax on it. We need to keep our valuable resources here at home in the US.
I believe that most old copper is now recycled, as the operators of a scrap metal recycler told me it's nearly 90%.

Copper requirements are likely to be significant, but there is the potential to substitute aluminum for windings at a small efficiency penalty.

I agree with others that GSHP are the future for heating.

They are:
- Carbon free.
- Electrical

Carbon energy is linked to carbon sources, with depletion.

Electricity can be made abundant with CSP in deserts.
Current price is 50% above current electricity prices (but no money going out of USA). This includes transport to the non-desert states. It is about 20% higher in desert states. But this price is FIXED FOR 30 YEARS (see Solana plant).

If you use oil heating, the bill will be split in three with GSHP and current electricity prices and split in two, when using CSP out of the deserts.


I agree with others that GSHP are the future for heating.

They are:
- Carbon free.
- Electrical

Carbon energy is linked to carbon sources, with depletion.

Electricity can be made abundant with CSP in deserts.
Current price is 50% above current electricity prices (but no money going out of USA). This includes transport to the non-desert states. It is about 20% higher in desert states. But this price is FIXED FOR 30 YEARS (see Solana plant).

If you use oil heating, the bill will be split in three with GSHP and current electricity prices and split in two, when using CSP out of the deserts.


They seem to pair pretty well with wind when its cold and CSP when its hot.
Plus CSP might help reduce desertification by shielding some of the desert from the sun and providing lots of desalinated water. Could grow lots of energy crops using human waste perhaps?

The Answer; Or

Why Lester Brown strongly supports biofuels

but, just doesn't know it, Yet:

All the techno-stuff sounds interesting and some people will scrape up the money. I suspect that wood and coal stoves will make another comeback in places where one of those two carbon carriers are plentiful.

However, not everyone will be able to afford a techno fix. For them, and maybe including me, cheap conservation measures may help keep energy used for heating to a minimum.

The first thing to do is turn the thermostat down and put on a knit hat. Yes, indoors because one loses a great deal of heat from the head even with lots of hair covering it. Until very recently, I lived in a charming but drafty rental that was impossible to keep warm all the time. When the wind blew from the north, I put on an old red knit hat and kept the thermostat at 63. Knit hats are cheap at the usual cheapo places.

Another clothing item to keep at hand would be a wool sweater. Wool is much warmer than cotton or acrylic, and to me, it is better than most synthetic fleece on the market. At least for women, thrift stores of all types carry wool. I myself picked up a nice LL Bean rag-wool sweater for a couple of bucks. It's a lot warmer than a sweatshirt!

My mom, who lives on a hill, adds another insulating layer to her 1967 double-hung "welded" glass windows using one of those cheap plastic wrap kits and a hair dryer. She leaves them up all year on some windows.

Another trick is to sew curtain liners from old blankets, or use any nice quilts as curtains in the winter. Bubble wrap also makes good insulation anywhere you can put it.

An even more novel way to insulate is to put up some board and brick bookcases against walls that are always cold, usually north and west facing. Go to yard sales and thrift shops in the summer, grab the old books and stack them up on the bookcases. Stuff newspapers in the spaces and then put some heavy plastic over the entire bookcase. It works folks.

All these little things can add up for people who don't have a lot of cash or who rent from a landlord who is uninterested in weatherproofing his rental place.

I'm sure that there are other cheap but effective tricks that the less fortunate may use to help keep warm on a reduced ration of fuel.

I've learned that it is not always possible to predict the future, so keeping a list of some cheap, low tech methods of staying warm may not be a bad idea.

There may asphalt peak oil problems?



This is also covered in "Alcohol Can Be A Gas"

Some Asian cultures use what is called Kang in Chinese, and Kotatsu in Japanese for keeping warm during the cold season.

OK, been lurking here for couple years now and finally a topic in my field of expertise. Being a home builder who has specialized in energy efficient homes since the 80's will allow me to speak w/ some experience here (finally). I love the Cogen concept but me thinks would only work in ecovillages or cohousing communities where residents are inherently cooperative. Maybe WTSHTF things will change but for now the idea of being dependent on a neighbors system won't fly. My advice to anyone who can get into their attic is to fill the sucker w/ as much cellulose as you can shove in their w/ the complimentary blower from local Home Depot or Lowes, just down block the vents at the soffits. Get yourself a small pellet or wood stove and learn how to power down. We've all been so brainwashed that we have to have the latest and greatest from Best Buy that our power consumption has tripled since the early 80's. One can live quite comfortably w/o all the electronic stimulation and the energy savings will follow. Conservation is the first and easiest step of power down and you'd be amazed at how easy it is to cut your elect. bill in half. If you're building a new house get it super-insulated and as airtight as possible. This is quite easy w/ plain old 2x6 construction w/ 1" styrofoam sheathing and a blown-in insulation blanket of either fiberglass, cellulose, icyinene, blue jean, or soy. Also make sure your trusses have a 16" "energy heel" which allows you R49 right out to the exterior walls. If you build a small house w/ this system you'll be almost a "near-zero" home and will require very little heat or AC.

No doubt, improving insulation is where to start in cold areas, along with insulation and solar heat deflection in warm sunny areas.

What is not mentioned is that there are plenty of people living in older detached, two-story, drafty dwellings. Many of these are living along on Social Security, and spend half their income or more on heating during the winter.

Many of these need to be condemned, the owners given fair compensation value and the materials recylced. They would have the option of either moving in with someone else in a simular situation, or moved into energy efficient "economindiums" described by Kermit Schlankser.

With regard to heat pumps and CHP, they are obviously a solution, but one best applied on a larger scale than single detached houses. I wonder about continuously extracting heat from underground without having a means to recharge the reservoir during the sumeer.

There is one development in Alberta, Canada (51 "condos")--Drake--I believe is the name that can get 90% of their heat from solar, by collecting it in the summer, storing it underground, and harvesting it the following winter.

For existing houses in the northwest, both solar and geothermal can be combined using the AVE to produce electricity to be distributed locally to run heat pumps. The geothermal would run at a maximum in the winter, while during the summer the AVE would make electicity from the greater amount of Convective energy available in the troposphere during that period, allowing the geothermal reservoir to "recharge" itself. This way the life of the geothermal reservoir can be extended.

Forcing older people out of their homes is easier said than done. I speak from personal experience. Some seniors would probably meet you at their property line with a shotgun, condemnation certificate be damned! IMHO, it will continue to be important to consider the personal and social needs of people while moving to lower energy living. Force will only meet stubborn resistance and, in the end, make the transition much more difficult and fraught with rebellion.

The better approach socially, would be to employ some of ecofeller's weatherproofing approach and my adaptive approach until said seniors pass on or could be amiacablt convinced to move to more efficient diggs. At that time, it would be appropriate to salvage the house and build something more efficient, especially if two or three adjoining properties could be combined in a duplex, triplex or fourplex.

Forcing older people out of their homes is easier said than done. I speak from personal experience. Some seniors would probably meet you at their property line with a shotgun, condemnation certificate be damned! IMHO, it will continue to be important to consider the personal and social needs of people while moving to lower energy living. Force will only meet stubborn resistance and, in the end, make the transition much more difficult and fraught with rebellion.

The better approach socially, would be to employ some of ecofeller's weatherproofing approach and my adaptive approach until said seniors pass on or could be amiacablt convinced to move to more efficient diggs. At that time, it would be appropriate to salvage the house and build something more efficient, especially if two or three adjoining properties could be combined in a duplex, triplex or fourplex.

I would rather see energy audits and upgrades for seniors on fixed incomes than an energy subsidy. Low income people can get a reduction on their power bills, but a better method might be to come out and upgrade the home so that it does not use as much energy.

Hi ecofeller, welcome aboard! Great post and some excellent advice. A high efficiency EPA-approved wood stove -- properly installed and WETT certified -- is a great investment, especially for folks who have access to reasonably priced hardwood or who can supply their own needs; as you probably know, it's a nice heat (particularly when you're chilled to the bone) and its operation is not dependent upon electricity, something that could prove important going forward.

I'm afraid I'm not nearly as enthusiastic about pellet stoves for several reasons -- while they do offer some advantages over wood log, pellet stoves require electricity to operate, they're mechanically complicated and potentially trouble-prone, and they're a lot more fussy in terms of the quality of their fuel (e.g., moisture content must be kept low and pellet size must be uniform). Because these machines have two or three motors, an electronic control board (which, btw, may not be too happy with the "dirty" power supplied by some, low-end generators), an igniter, a photo eye and various mechanical components that are susceptible to ash and dust build-up through the course of normal use, they do require a thorough cleaning/tune-up at least once a year and for those of us, like myself, who don't know which end of the screwdriver to hold, budget between $150.00 to $200.00 a year for a professional service call -- that's an expense that could wipe-out 15 to 25 per cent of the expected savings right off the bat. In addition, homeowners must shut down their stove once a day or every other day to clean the ash and clinker build-up within the combustion chamber. Likewise, they'll need to clean the venting about every fifty bags and, trust me, this is not something that can be ignored. Due to their constant neediness and often temperamental behaviour, I refer to these products as the "Plymouth Volare of heating technologies". Anyway, this is personal opinion so take what I say with a healthy dose of salt.

As it turns out, I'm currently working on a two page pamphlet for a client that compares the advantages of pellet technology to that of (surprise!) ductless heat pumps; a draft copy is available in PDF format here:


I have had a pellet stove for 15 years and I have to disagree with some of your comments.

Basic stoves do not have a an electric eye and auto ignite system, and this is good. Lighting the stove is a bit of an art, but once you learn the drill, it is no big deal. I have no idea what brand of stove you are talking about that needs to be shut down every day. I have run mine continuously for three weeks, and only had to scoop out ash once in that period - A two minute job that did not require a shutdown. Likewise cleaning the venting every 50 bags? Where are you getting this? I clean mine once a year. Professional maintenance? The interior of mine (which is an "Englander") consists of cast iron plates hung from hooks. I remove them once a year and scrape them clean. A dirty one hour job that doesn't even require tools.

Yes, there is a circuit board even in my basic model. I have had to replace it once in 15 years, a 20 minute job that required exactly one tool: a phillips head screwdriver. The cost was $90. I had one of the auger motors go on me gradually last year, and I replaced it at a cost of $130 over the summer. Again, I needed exactly one tool, a 10mm open end wrench, and it took all of 10 minutes.

There are a few things you learn to live with.

You put in a 40lb bag of pellets every day. I have had no problem with any of the fuel I have bought at any outlet, and I am sure I have used ten different brands by now.

You do not want to have the stove running unattended if the power goes out, unless you installed the air intake to the outside. If the stove loses power, your house will rapidly fill with smoke because the exhaust fans are dead. You can run the air intake to the outside of the house to prevent this, this is code, but it cuts efficiency so much that almost no one does it. Instead, I bought a computer UPS that will run the stove for 1/2 hour. If there is a power outage, that gives me 1/2 hour to shut down the stove, or have the power come back. We have only had one power outage of more than 10 minutes in the last few years, and I was not running the stove, so I did not have a problem. The newer, fancier stoves have internal UPS with automatic shutdown. There is a risk, of course, of a long power outage when you are not at home if you do not have an auto UPS interface.

I have had many thought sessions about how to make a pellet stove that does not require electricity. A very large wind-up spring and a stirling external combustion motor might work.

Thermoelectrics may be sufficient to operate a pellet stove once it's lit.  Not very cheap, but solid-state.

" You can run the air intake to the outside of the house to prevent this, this is code, but it cuts efficiency so much that almost no one does it."

Could you expand on this? It doesn't quite click for me.

Hi Nick,

In the case of mobile and manufactured homes, code requirements here in Canada require pellet stoves to be supplied with outside combustion air. In terms of operating efficiency, outside air makes more sense because you're not exhausting room air that has been previously heated (these things are much like a kitchen fan in terms of the volume of air they expel). On the other hand, an outside air intake, even when directly connected to the stove, can potentially spill cold air inside the home when not in use, so it could be a bit of a toss-up. Even so, I suspect you're still further ahead using outside air in terms of operating efficiency.


Hi moabite,

I'm glad to hear your experience has been positive. It would be inappropriate for me to identify specific brands by name, so I'm going to be somewhat coy in what I say, if that's OK with you. FWIW, our family business sold pellet stoves for twenty years and as much as I'd like to say all our customers have been thrilled with their purchase, that's hardly the case. Brand "W" who invented the technology was the first brand we carried and some of the earlier models such as the "Q" and "A" / "A II" were great performers. Unfortunately, when their operations were bought out by "L Corp." and relocated to Tenn. things went south quickly (and I'm not speaking just in geographical terms). Let's just say the "P" 20 and "P" 30 are not cut from the same cloth and that dealer support leaves a whole lot to be desired. We were one of the few remaining dealers to carry their products in Atlantic Canada and we eventually threw-up our hands in disgust. We also carried Brand "H". We always understood Brand "H" had a solid reputation in the industry but our experience was not so good and bad timing may account for much of it. This company ramped up production like crazy when oil prices shot up in 2005 and they literally couldn't push them out the door fast enough and, not surprisingly, quality took a big hit. Just about every Brand "H" we sold had ongoing issues related to failed control boards, auger motors, combustion fans and igniters. One customer had his igniter and control board replaced three times in the first year of ownership and we ended up buying back his stove -- at our expense -- because technical support were unable to properly resolve the problem. As it turns out, Brand "H" ran into financial difficulties when pellet stove sales slumped the following year and the company was stuck with excess inventory; it has since been sold to a major hearth player for a modest $40 million. We also sold a European model (Brand "DP") that ran on DC and had an internal battery backup and I'm not going to say another word about that nightmare. Oddly enough, the most reliable pellet stove we sold in recent years (Brand "EF") is made by a Canadian company out in B.C. and it's one of the least expensive products out there.

Manually started stoves are getting hard to find now -- most homeowners don't want to mess with gel starters which is another ongoing expense; automatic start is a lot more convenient and allows the stove to be operated by a conventional wall thermostat which is a big plus. In terms of daily shutdown and cleaning, the only one that could be operated for more than a day or two at a time is Brand "H". In this case, pellets are fed from the bottom up and the ash and clinkers are pushed out of the combustion pot and drop into the collection bin. All other brands are "top feeders" and thus you have to clean the ash and clinkers that build up inside and around the combustion pot. I would never recommend doing this while the stove is operational and every owner's manual I've read is pretty clear on this point. And if you don't regularly clean the inside glass, removing those baked-on deposits is nearly impossible.

Our company charges $179.00 ($202.29 with HST) for an annual maintenance and cleaning. That barely covers the cost of our technician's wages, shop supplies, vehicle lease and travel related expenses. It takes, on average, two hours to strip down one of these stoves and do a proper cleaning and whatever adjustments/fine tuning that may be required (insert models without rails are a real b*tch). Some of our customers are happy to do this work themselves and that's OK with us, but most don't want to mess with it and if you don't use a proper soot vac, mess is, in fact, the operative word.

Hope this information is helpful. I'd be happy to elaborate on any of this in greater detail if you so wish.


Well, I mentioned the name of mine in the post. "Englander". They have been made for years, and are simple, inexpensive and reliable. The auger pushes the pellets into the burn pot from the back, and the ash gets pushed out the front. I might flick the crust off the front of the burn pot if I happen to be thinking about it, but it is not necessary. I would not buy a stove that required me to shut down and clean every day, and mine certainly doesn't require that, nor does it requires pipe cleaning more than once a year. I have only dealt with the manufacturer twice to order the controller and the auger motor, and both times they were very helpful, and the part arrived within a few days.

I guess I'm not surprised that in this automatic transmission world people want an automatic igniter, but I tend to run the stove continuously anyway, so lighting it is not that big a deal. I have never relied on commercial gel to light it. Make some sawdust and wax firestarters (or buy them), and spray on some silicone spray grease. Don't try this at home kiddies, but it works great and doesn't cost an arm and a leg. If you burn your house down don't call me. Before I got lazy, I would light it without the grease jumpstart, but that definitely makes it easier. Once it is lit, just keep adding bags of pellets until the weather warms up.

Hi moabite,

I'm not familiar with the Englander brand but I would keep this unit running as long you can as it seems to fit your needs well. If this particular stove uses mostly generic, off-the-shelf parts you're well ahead of the game; as a dealer, we often pay two to three times more for an OEM part even though the only difference is the part number on the box. When you get into some of the major brands, cheaper generic parts are not always available and you will pay dearly for this.

In terms of pellets, we have a choice of two brands locally. One is excellent and sells at a small premium and the other is total crap (the latter is produced by an oil and gas interest in a neighbouring province that also owns a major pulp and paper concern and a big box home improvement chain among many other things). It's also important not to carry pellets over from one heating season to the next and to store this fuel in a dry location and not in direct contact with a concrete floor where moisture can wick through the bag (our summers are not especially hot but they are humid and so moisture is a big issue for us). If folks would buy good quality pellets and follow these simple rules and properly maintain their stoves, there would be far fewer complaints and the guys in the parts and service wouldn't have to roll their eyes every time they answer the phone. But anyone who expects a pellet stove to offer the same simplicity, cleanliness and reliability of a gas fireplace is in for a rude shock because it just ain't gonna happen. ;-)

Lastly, you have to take a hard look at the numbers to see if a pellet stove makes sense for you. Two years ago, we could buy a 40-lb bag of pellets for about $3.29. Today, that same bag will set you back $4.80 and this has diminished the economic performance of pellet considerably. Check out the following cost comparison table from the N.S. Department of Energy:

At $250 per ton, pellet isn't that much cheaper than electric baseboard heat -- the difference is less than $600.00 for an average new home or $400.00/year if you have your stove professionally serviced once a year. In addition, replacing a faulty control board or combustion fan out of warranty could literally wipe-out your savings for the entire year. And, sadly, there are a lot of reincarnated Plymouth Volares out there just waiting to suck you dry.


I bought a ton of pellets for $220 earlier this year. Unfortunately, my primary heat source is a forced air propane furnace at $3.05 a gallon, and pellets at $220/ton are way cheaper than that. I also have a very inefficient fireplace that I use.

At the time I installed the pellet stove in 1993, pellets were $150 a ton, so they have gone up considerably, but at that time propane was .75 a gallon, so it has more than quadrupled. I live in Colorado, and there are millions of acres of beetle killed dead trees standing here. I can have all the softwood firewood I want free for the cutting, and there are two pellet factories about to come online here to dispose of the dead trees. I don't know what price the pellets will carry, but hopefully they will come down a little.

Hi moabite,

$220.00 per ton is a great price and it sounds like your supply situation should remain healthy, at least over the near term. Two years ago, things were not quite as bright in CO as this article attests:

And out on the west coast, you can add "Peak Sawdust" to the list of woes:


Some great points in this posting! I have been looking at co-generation for my house for many years, unfortunately could never make it pencil out. Linking multiple houses makes a lot of sense...

Here in Fairbanks, Alaska we have 2 large co-generation plants operating; the first, at the University of Alaska Fairbanks, has been providing all the power and most of the heat for the (5,000+ students) campus for more than 30 years. The second provides heat and electricity to central Fairbanks. I don't know how much heating oil this displaces, but I'm sure it is huge.

Linking multiple houses makes a lot of sense...

I figured they'd just be linked through the grid.  This would require some tariff changes.

Is UA Fairbanks still operating the coal-slurry diesel cogenerator?

Yes, they are.

E-P, it seems to me that the largest barrier to this idea is regulatory.

AFAIK, currently the only provision for selling residential cogenerated power is net-metering, and that's not really designed for net power sales - one either loses any net annual surplus, or gets paid a much lower wholesale rate.

Does that make sense? Are you aware of anything different?


In warmer climates you might be able to keep your annual production under you annual use of electricity so you would avoid the cap on production, but in many states net metering is limited to renewables so natural gas would not count.
Click on the entries in the net metering column to see rules for each state that has net metering here:

In Maryland, where we probably cool as much as we heat, you'll find this:

Eligible Renewable/Other Technologies: Photovoltaics, Wind, Biomass, Anaerobic Digestion


currently the only provision for selling residential cogenerated power is net-metering

You're absolutely right, and this would have to change for a power-sharing scheme to work.  Fortunately, this is not an engineering difficulty, just an accounting issue.

One thing I didn't touch on is the issue of grid services that cogenerators could provide.  During the heating season (and year-round if the cogenerators also supply DHW) the cogenerators could provide:

  • Power on very short notice (not spinning reserve, but close)
  • Reactive power while running.
  • Possibly, short-term regulation services.

These services may pay well enough to support a fair amount of the system cost, if the AC Propulsion white papers on V2G are any guide.

With an SOFC you could run at partial power and heat water, but in the summer you could cool the house using absorption AC. Any heat source above 200f will power a single stage cooler. Imagine cooling the house and generating electricity for your neighbors that still have compression AC.

The Japanese are giving fuel cells a go:

Linked from 'Drumbeat'

I am a lot more hopeful of fuel cells for the home than in cars - not the same weight restrictions, and you can avoid rare and expensive catalysts if you choose the right chemistry.

Unfortunately it doesn't say what they are using here.

Solid oxide
CeresPower - Fuel Cell Technology fuel cells would be good:

Great post E.P.
Since the c.o.p. of the thermal mass is being leveraged to confer greater efficiency.
I have wondering whether reducing the time that the pump runs to extract the heat (ground source heat pump)would be of a greater advantage versus generating supplemental energy from wind/solar to run the pump.
Solar thermal is superb and wind can be used to generate heat. Research at Cornell in the 70's showed that water churned in a airtight container could be heated quite efficiently.

As usual, I'm late to the party here, so my post will probably not be read. C'est la vie.

Interesting idea Engineer Poet. Why didn't I think of it? Oh wait! I did! Check out my (rarely updated) blog:

About 16 months ago, I put in ground source heat pumps. They work great, but they haven't had a terrific payoff, although with increasing heating oil prices, this is changing. One thing I noticed after installing the heat pumps was the major increase in electricity use. Seeing that, and noticing I still need second-stage heat anyway (the heat pumps are sized for the cooling load), I looked into cogen. That was a year ago.

I have purchased a cogen unit. I'm an early adopter of this, and there weren't many choices available a year ago, but I chose the ecopower:

It has taken a year to get this thing going for a variety of reasons. A big impediment has been the local power company, but here in CT we have a good net-metering and a competitive excess generation law here, and they have finally approved the design and installation of the ecopower unit. I'm told I'm the first residential installation in CT for a grid-tied cogeneration unit. Wiring/plumbing has commenced, and finally, after a year, this thing should be up and running in another 2 weeks or so.

My estimate is that the generator will run 50% of the time for my needs with the bulk of that in the winter of course, and my power bill should go to zero. It could in theory go to a credit, but the electric generation cost is too high for stand-alone. I know it isn't exactly what you had in mind, but it is an interesting idea to think about farming out my excess heat to my neighbors!

Actually, this is a retread of an Ergosphere post from about 3 years ago.  I don't know when you wrote your piece but it doesn't matter; this is a fundamental improvement in methodology that's not getting enough press, and the more at this point the better.

Farming out heat to the neighbors (as opposed to electricity) is an interesting notion, but not too practical as heat doesn't travel well.

Please take my initial comment as "great minds think alike." From reading your columns, you've definitely been thinking about all this longer than I have. At any rate, I didn't see a reference to the ecopower, and I wanted to get it out there, for indeed the technology is now available and under-utilized.

I was thinking of your every 3rd house a cogen with the other 2 heat pumps. It looks about right but may be a bit optimistic. I'm in Southern CT, one hour from NYC by train (yes, we have one or two of those here). My power usage has a winter peak, due primarily to the heat-pumps. If I were to run the co-gen all-out, about 1/2 to 3/4 of my heating needs would be met, and I'd probably generate enough juice to power one of my neighbor's heat-pump needs but not both.

The heat-pumps here are not a great deal, because the power costs here are high. They'd be better in the Midwest where coal is still the marginal fuel (as opposed to nat gas here). That could change pretty quickly if a critical mass switched out their furnaces for cogens.

This can work as long as the outside air is above 35F. Below that, the COP falls off quickly (outside coil ices up), and you are back where you started from. Use of a ground source heat pump can eliminate the icing, though are prohibitively expensive for the average home.

This can work as long as the outside air is above 35F. Below that, the COP falls off quickly (outside coil ices up), and you are back where you started from.

Hi Will,

As noted in Heading Out's GSHP thread linked above, the York BHX024 is a conventional air source heat pump with a somewhat modest HSPF rating of 8.0 (the federal minimum standard now being 7.7) and its COP at -23C is still pretty decent at 1.95. With respect to the impact of ice build-up on the outside coils and the energy penalty related to its removal, see:


Use of a ground source heat pump can eliminate the icing, though are prohibitively expensive for the average home.

Groundwater is an alternative source to standard ground loops, and there is no reason why adjacent buildings could not share a source well and dry well to reduce costs.  I strongly suspect that if we needed to cut the cost, we could.

Just joined your interesting club – background: registered ME with 30 years of commercial building mechanical system design. I’ve done a lot of air source HP and GSHP systems.

Three points

Air-source heat pumps - There’s a recent twist to the air-source heat pump game. Dual-fuel systems. Use an air-source heat pump outdoor unit and a gas furnace indoor unit. The thermostat has an outside air sensor. Whenever the outside air is, say, 45 degrees F or above, it switches to heat pump mode to heat the space. This puts the air-source HP in its most efficient mode, with COP’s of 4-5 and no defrosting issues. Gross heat output stays near nameplate output. No supplemental electric heat strips are required (electric resistance heat strips – talk about a waste of entropy!)

When the temperature dips below 45F, the thermostat switches to the gas furnace. In much of the US, the average outside air temperature is high enough to keep the heat pump working most of the time. This option is most popular in the low elevation northwest and other areas with a combination of low electric rates and relatively high average winter temperatures.

GSHPs – many people make the expensive mistake of sizing them like they size conventional systems -sized to match the design load with a large “safety factor”. Before we start design, we get aggressive with the architect or building owner to get them to enhance building energy efficiency. It is usually lot more cost-effective to upgrade to low-e windows, use BIB insulation, cool roofs, etc. than to add more GSHP tons. We then design the GSHP system to exactly match the heat loss or cooling gain at the ASHRAE 0.5% design temp and a “reasonable” inside air temperature, not the extreme temperatures and 70 degrees in the summer. No oversizing. We demand tight, short ducts, preferably in the conditioned envelope. Also, because GSHP COP's and output vary with ground temperature, not air temperature, we don't need to "de-rate" the equipment for peak outdoor summer or winter conditions. We usually end up with half the nominal tons of a “conventional” system. This reduces the sticker shock, as the price/ton is about 2.5 times conventional, but with half the tons, the net cost can be swallowed, especially if there are some utility rebate.

With this approach, the GSHP market started to take off here in California a few years back, but then vertical bore costs skyrocketed the last three years as most of the drillers with GSHP experience were also gas/oil drillers. They went off looking for more profitable holes to dig. Seems water well drillers (at least in California) just can’t understand the concept of drilling a 5” uncased hole, sticking in a pair of 1” poly pipes, and backfilling with quartz-enhanced Bentonite.

Final point – there is nothing new under the sun. Back in college in ’74 , I did a research paper for a thermo machinery class on a diesel-fired heat pump system concept that incorporated engine jacket and exhaust heat recovery. It had a net “efficiency” way over 100% during mild heating conditions. And in 1992, I designed a micro-cogen system for a health center that had an indoor pool in a coastal climate. The cogen generator provided the power for the pool pump and the engine jacket heat heated the pool. Worked great for as long as I kept track, but I can’t say what the current condition is. These types of whiz-bang systems are maintenance-intensive and once an engine throws a rod, future owners are apt to go for the more conventional and lower first-cost solution.