Cogeneration At Home: Ceramic Fuel Cells And Bloom Energy

[Comments fixed.]

The Engineer-Poet recently had a post on The Cogeneration Stopgap at the Oil Drum, which looked at how the combination of cogeneration (generating combined heat and power - CHP - using natural gas) and heat pumps could be used to heat North American homes much more efficiently and extend the life of North America's dwindling natural gas reserves for a period of time while houses are retrofitted to make them more energy efficient and natural gas use is replaced with electricity. The only example of cogeneration technology touched on in the article was from Climate Energy, whose CHP unit is made by Honda.

An Australian company working in this area called Ceramic Fuel Cells was in the news recently after landing a $240 million deal with Dutch energy company Nuon to supply 50,000 CHP units by 2014. The company still needs to meet a number of commercial requirements set by Nuon - in particular improving the durability of the cells from two years to four.

The company is hoping that production will begin by June 2009 in a new €12.4 million factory in Heinsberg, Germany, which aims to produce 10,000 2 kW units per year. The cells are expected to emit 60% less carbon dioxide than traditional combustion generators. The company is also partnering with Britain's Powergen, Germany's EWE and Gaz de France.

Ceramic Fuel Cells

Ceramic's fuel cells have been under development for several years, listing on the ASX in 2004 and the AIM shortly after. The company specialises in solid oxide fuel cells, which convert natural gas (and presumably biogas) into power and heat without burning the fuel. The cells convert about 50 per cent of the energy in the fuel to electricity - traditional gas-fired power stations manage around 30 per cent - with another 35 per cent of the potential energy captured as heat from the catalytic process.

The company doesn't have any plans to market units in Australia in the foreseeable future, preferring to concentrate on the European market due to higher energy prices, specific CHP rebates in Germany, feed-in tariffs and possible carbon credits for trading on the EU emissions trading scheme (set up under the Kyoto protocol).

CHP in Britain

Reuters reported that boilers containing Ceramic's units could be sold in Britain in 2010 if utility company Powergen orders units this year. The article estimates that fuel cell units for home units will be priced between 1,500 and 2,000 pounds and that larger units priced at over 3,000 pounds will be operated by utility companies. The same report goes on to speculate that because utilities will save so much money by producing electricity using CHP (which they believe is twice as efficient as centralised generation and sending power through the grid), that they expect utilities will eventually start giving next-generation boilers to customers for free, with the units having a 4-5 year payback period.

Powergen has also previously looked at a different micro-CHP approach using Stirling Engines attached to water boilers. I can't tell what happened to this plan, though the company is assume was the prospective supplier - Disenco - is still marketing a CHP product (although full production isn't due to begin until this year, which may explain the absence of progress).

Another British CHP company called Ceres Power received an order for 37,500 units from British Gas owner Centrica in January, for delivery from 2011. These units are smaller but cheaper than Ceramic's units. Carbon Commentary have looked at this unit and claimed the main challenge facing CHP vendors in the UK is a the lack of feed-in tariffs - which would presumably affect Ceramic as much as Ceres.

Bloom Energy

Another company that has received a lot of attention in the fuel cell market is US company Bloom Energy, who are also developing solid oxide fuel cells (though there is some legal argument underway about who actually developed the technology in this case). Bloom Energy

The company is investigating using natural gas and ethanol as fuel for the cells, and most reports speculate the cells will be able to generate 100 kw of power (the company's web site says absolutely nothing). One report from Business 2.0 claims the company is aiming to sell units for around US$10,000.

Bloom is backed by a number of high profile investors, including the omnipresent Kleiner Perkins Caulfield Byers, and has raised US$100 million in funding. According to Vinod Khosla, the company is currently building a "massive" facility in Mumbai, India.

One possible application for Bloom's fuel cells is in data centres, with the cells used to eliminate the need for uninterruptible power supplies (UPS's) and thus (in some cases) the need for additional disaster recovery (DR) facilities.


Japan has also seen trials of hydrogen fuel cells for CHP, with the hydrogen coming from reformed natural gas. The cells are leased for 1 million yen (US$9,500) for a 10-year period from Matsushita Electric Industrial Co. Toyota, Honda and Toshiba are all also working on fuel cells, usually as part of efforts to develop fuel cell vehicles.

The Japanese Government is spending 2.4 billion yen (US$310 million) per year on fuel cell development and plans for 10 million homes (25% of Japanese households) to be powered by fuel cells by 2020.

The Air Car

One last note - a commenter on the "Air Car" articles noted that MDI's main business seems to be a variable-fuel stationary power supply, so presumably they could be a vendor in this market at some point as well.

Crossposted from Peak Energy

The problem with this technology is that it arrived 20 years too late. Notwithstanding the cheaper prices it seems odd to become more dependent on fossil fuel. I'm not sure how long the Dutch will have reliable gas but the Japanese will need those bubble boats to keep coming in from places like our NW Shelf. Re which south eastern Australia will be experiencing gas supply problems within a decade. If I recall even the basin (Browse?) that supplies Perth may not keep up with demand.

I haven't run the numbers but I'm sure biogas can't get close to making up the required volumes. Therefore I think the future of home heating is local biomass, electrical or conservation. We should save gas for for crucial needs such as peak generation, fertiliser production, food processing and gas-to-liquids jet fuel.

As EP noted (as did I in my post on Bloom Energy last year) - this is a stopgap solution, not a long term one.

If you can get a 50% increase in efficiency (and reduction in emissions) then this is a step forward at least, and a useful one for the next couple of decades...

That's also the crux of the 'nuclear bridge' argument. Nobody knows if extended fuel cycles will be economic but it could free up energy to construct lower average yield renewables (ie when backed up).

I guess FC-CHP with feed-in tariff could work for an operation that only requires low process heat, a baked bean factory perhaps.

I know a little about Bloom. The assessment of the stop-gap nature is correct - nat gas is the main feedstock, rather than hydrogen and that's deliberate. Bloom is counting on the infrastructure for nat gas being around (and the gas itself) to build a solid market in fuel cells for small business, offices, data centers etc. The home market isn't ready and the economics are not there either for Bloom.

Someone else may have more pertinent information, but the modular design of Bloom's 100kW unit suggested to me that they were looking to a pure hydrogen approach later, but well after they had established a market.

One of Bloom's key differences in R&D is their reliance on first principles modelling technology for the development of the fuel cell, which usually leads to a shorter design cycle and has also allowed for an efficiency gain over nearest rivals. The main target of Bloom I think is absolutely correct - medium size diesel back up generators in small industry, health care etc. And I would expect that they will stay close to home initially, the San Fran to Oakland area, where there are plenty of markets for IT related back up gen replacements.

I figure fuel choice will end up being wider for the stirling approach...


Good to see you found a New Zealand company for the list - I should have done some more searching...

Is there an argument to be made that household CHP would reduce the baseload generation requirement (all those electric hot water systems)?

Of course at the expense or requirement of then distributing liquid or gas fuels.

A technology for the periphery perhaps... where it's more economical to move fuel rather than build the infrastructure to move electrons? Of course it might just be cheaper and simpler to have a diesel genset and solar hot water in those cases.

What hasn't been done yet is to use the reject heat for driving a cooling process... perhaps using the adsorption methods (eg activated charcoal:ethanol or water:silica)

I think CHP has its niches - for example, apartment blocks, where solar hot water isn't really an option, or buildings located in areas with poor solar availability.

Once again - its a stopgap - an efficiency measure to make our gas supplies last longer.

Not sure about reject heat - thats what I like about the Stirling engine ideas - presumably the engine captures and harnesses the excess heat.


Its more the other way round you initially use the heat to drive the stirling engine the excess heat is used to heat the water, EP dismissed whispergen as they have a 10%/75% (0verall 85% efficient), But this is as much driven by their target markets (replacement of domestic boilers). There are a number of regulatory etc issues with feeding power back into the grid which need to be dealt with, ie our whole system is setup based on individual households as consumers and this works against cooperative energy generation & useage. I'd like to see electrical regulation that commits distributors to designing the electric grid as a 2-way network otherwise all these CHP systems will fail to get a foothold until energy prices are excessively high (ie when it is far to late)

Neven MacEwan B.E. E&E

Ooops - thanks for the correction.

I agree with your comments about electricity pricing - net-metering should be mandatory at a minimum - but preferably some form of feed in tariff that lets distributed generation compete better with centralised generation schemes.

The problem with WhisperGen in particular is the very low thermal efficiency and high capital cost per watt.  Perhaps they made tradeoffs for lifespan, but IMAO we'd be far better off with SOFCs at 50% than a Stirling at 10%.

See UK Carbon Trust test report on Whispergens plus a few other sorts of small CHP at

IMHOP they need a feed-in tariff to get them deployed.

From my observations, because the CHP units work most in winter daytimes their electricity is more valuable that 'average' unit rates..

and they are good at cutting the peak winter electricity demand flattening the demand curve for a happy coexistence with other more base-load plant.

There are lots of tunes to be played on this kind of plant yet. It is early days.

A fuel burner is still a fuel burner.

The solid oxide fuel cell looks like it will save 60% of the natural gas input for the same electric output, but natural gas is disappearing.

Electricity from massive wind and solar(2 watts renewable per 1 watt of load) for with large scale energy storage and a modest fossil fuel backup will reduce natural gas by up to 80% in studies.

Fuel cells will only make sense in countries with the largest fossil fuel resources.

Renewables first!

See note Fig. 2 below.

The solid oxide fuel cell looks like it will save 60% of the natural gas input for the same electric output, but natural gas is disappearing.

Natural gas is nice, but hardly required.  SOFCs can run on gasified biomass or waste; the Gas Technology Institute ran one on gasified chicken litter.

Renewables first!

There are many possibilities for renewable inputs for fuel cells, and the higher the efficiency the less we need and the more we can afford to pay for it.

Thanks for pointing that out EP - I was going to mention this in one post or another, but forgot in the end - you can use biogas to fuel these things - so they then become a more efficient way of using a renewable resource.

But in any case - more efficient use of reular natural gas shouldn't be sneezed at - its not a panacea, but it does help us transition to energy efficient buildings.

On a semi-realted note, check out this new glass for helping buildings to become energy neutral :

in theory, yes. in practice, not quite. lots of coking and fouling of the system results. for example, a huge supply of waste glycerin from biodiesel production exists. lots of potential energy, but very messy when combusted. same for black liquor from paper production, etc ...

sort of like the reports that someone falls out of an airplane and lives. perhaps, but only for a millisecond after impact.

You people are behind the times on stirlings vs fuel cells. Why not? There is too little on the web that is up with it, so I will fill you in.

1) stirlings have beaten fuel cells in recent head to head contests on a lot of things like CHP and small battery replacers and such-like little power generators. Stirlings are fuel insensitive ( run fine on diesel, or wood chips) and last a long time- many years -and are fairly efficient (maybe 20% + efficient system fuel to electricity at 100 watts out).

2) They are just metal, no magic membranes or any such $$ stuff needed. Very ordinary kinds of hardware we all know and love. No fundamental reason a stiring should cost more than a couple of times an IC of same power (needs some hot metal the IC does not need)

3) Built right (that is, free piston, not cranks), they are nearly silent and vibration-free.

4) They are way more than just a stop-gap. Anywhere fuel is being burned, a stirling could get a good bit of the available energy from that heat as electricity. This goes for now- and forever.

5) Stirlings are good for solar. Very good. and getting better.

6) "If they are so good, why can't I buy one?" Dunno. Ask the money people. Meanwhile, read the blurbs.

You don't believe me. The stuff up there is just company brags. "Where is your reference?" Hey, it's Sunday; I am not being paid for this. I hit a few search questions and didn't get what I wanted. That does not mean I am wrong- just lazy. You do it- it's out there somewhere.

They are way more than just a stop-gap. Anywhere fuel is being burned, a stirling could get a good bit of the available energy from that heat as electricity.

It's a stop-gap because architecture is bound to eliminate most of the need for heat through improved design.

EP. First, thanks again for all your good work.

What I mean here is that if you are using something that generates a lot of available energy and does not use it, such as for example, any combustion process used for mere low temp heating, then you can get some of that available energy by a stirling. I am sure you are fully aware of that.

Of course, to do combustion for just low grade heat is atrocious in the first place, but done all the time. And I completely agree that building heating need not be in the first place, if good design is used. Trouble is, we live in a highly unoptimized world. Wish it were not so.

But my real message, somewhat filppantly delivered, is that stirlings have got pretty good, and deserve a bit more recognition/use than they are getting. And of course, so also for some fuel cells, although I personally believe the merits of fuel cells are not equal to the hype/$ they have received. A wholly prejudiced remark, of course, from one who might, if extremely lucky, get some financial reward from any market success of stirlings.

If you really want to get efficient, you could always use a Stirling engine as a bottoming cycle to recover work from the off-heat from an SOFC.  IIRC, this is already being done with small gas turbines on MCFCs (but at a scale much too large for heating individual homes).

SOFCs and MCFCs can do things Stirlings cannot:  they can extract electricity at high efficiency and supply the waste heat at temperatures high enough to perform lots of industrial processes (it's hard to bake coatings or anneal metal with the hot water from a Stirling).  The difficulty I see with Stirlings is that they're mechanical, and present problems over and above those already solved in combustion engines.  I'd love to have one that runs off a wood stove and generates a couple kW, but I don't expect to be able to buy one with anything like the 10-year warranty I'd consider minimal.

Ok, how about 15 years continuous run w/o mantenance? That's what NASA demands and will get from its isotope heated stirlings. By that time, anything is obsolete and should be replaced just for that reason alone.

As for the wood stove, right, just what I have been working on, and actually have got, except its cost is a bit high, maybe 50K for that one-off prototype. But if you take the material cost and multiply by an experience factor, you get a good number mere mortals can afford- around 2K/kW for the whole thing, wood burner included-- with a load of nice dry hardwood as bonus. Smoke free, of course.

But all that is mere fun and games. The real serious target is solar thermal in the desert. I am putting my bets on stirlings to beat all at that application. Fuel cells need not apply.

Just two questions:

  • How much do they cost?
  • Where and when can I buy one?

I've got nothing against Stirlings, but it looks like the fuel cells are headed for the consumer market faster.

Are you talking about SOFCs? What evidence do you have that they are close to the consumer market? I certainly do not regard the above post as such evidence. At least Whispergen is selling Stirling generators in the yachting market with reasonable warranties. I am not trying to defend Stirlings which I do not believe will make much impact in the CHP market. I just haven't discovered any evidence that SOFCs are close to being ready for prime time.

Are you talking about SOFCs? What evidence do you have that they are close to the consumer market?

Among other efforts, Delphi is developing SOFC units for vehicular APUs and other uses.  These 2-6 kW units are in the ideal size range.

Bloom Energy comments:

100 KW generation in each house? Seems a little high. Perhaps a tenth or even a hundredth of that?

$10K/unit? Yeah, that would be good, but is it realistic? No backup information on that one.

The large units seem to be destined for industrial use (like the server farms mentioned).

Home scale units would presumably be in the 1kW to 5kW mentioned for the other manufacturers.

Getting information about Bloom is quite difficult - they have been pretty reticent so far and media reports don't have much concrete detail.

I don't know where this article got it's info from, but a brand-spanking new combined cycle nat gas plant can get as much as 60% efficency. I don't even think that simple cycle nat gas plants are even that low. Even with coal plants, even old sub-critical plants get as much as 32-33% efficency, while ultra supercritical can get up to about 40%.

Also, using nat gas for space heating/hot water heating is inefficent--unless of course you look at all the other alternatives (excluding heat pumps/solar hot water, which should be mandated by law for all new buildings because retrofits are horrifically more expensive). Using oil or electricity for those tasks are both absurdly more expensive and carbon intensive than using natural gas.

Personally, I think that the proliferation of solar will put a major dent into natural gas use for electricity. Since natural gas almost exclusively produces peak load power, which is highest in the summer during mid-day, which is when solar production peaks, new solar will do a number on natural gas consumption, particularly solar thermal in terms of nat gas consumption reduced per watt (less variable on a minute to minute basis).

Yes, I'm not sure where the numbers come from.

I have a nat gas boiler rated at circa 90% efficiency; combine this with a 60% efficient modern NG electric plant, and the projected fuel savings are simply not there - you'd be violating the laws of thermodynamics..

This discussion once more gives me the opportunity to recommend a fascinating and free online magazine:

This is a U.S. publication, and it is also easy in the U.S. to get on the mailing list for a free print copy bimonthly.

The area of DG(Distributed Generation)is growing fast, with technical innovations occuring and effeciency rising almost daily.

Those involved in the various facets of this energy are very intelligent about not seeing any one solution in isolation, but instead looking at an integrated approach, using not only fossil fuels but also incorporating renewables, energy storage and conservation engineering into the mix.

I am always fascinated at how easily many here dismiss alternatives almost out of hand as not viable that the Japanese and Europeans are spending hundreds of millions of yen/Euro on, and seem fully intending to install in the millions of units. I suppose it can be assumed that the technical departments of firms such as Honda,Toshiba and Matsushita Electric are completely mistaken and wrongheaded, but I am not sure I would bet my money against them.

Distributed Generation does not in many cases create 100% freedom from fossil fuels, but in many cases it does offer the prospect of huge efficiency gains, the ability to recapture waste heat, and a way of overcoming the variability of wind and solar. In markets such as the U.K. which will have a natural gas supply for many years into the future, but at a declining rate, Distributed Generation could be path forward into leaner energy future.

Is it THE solution. No. But does it have enough potential to be worth further development and study. Absolutely.


Big Gav and TOD readers should be aware that other micro-cogen systems exist, including one which is manufactured in my home state:

Note that I do not have any vested interest in promoting this company. In fact the smallest unit they manufacture at present is probably too small for most homeowners, but it appears to be appropriately sized for apartments, small businesses, and other situations with a somewhat larger year-round demand for hot water, space heating, and other low-temperature heating load.

Micro cogen need not be based on fuel cells - a properly designed diesel engine system will convert a very respectable percentage of fuel energy into electricity. As is the case with hybrid cars, people are fixated on new, sexy technology rather than stuff like the good old diesel engine, which has been steadily refined for over 100 years. (I know a number of guys who get more than 50 MPG with their turbocharged VW New Beetles.)

As for usefullness of micro cogen systems after the fossil fuel age, I would suggest that bio-methane will be a perfect "plug and play" replacement for natural gas. We can use all the existing infrastructure and devices.

This (ignoring bio-methane to replace natural gas in homes and businesses) is yet another example of the stupidity of Amerka's obsession with bio-based motor fuels. Sorry, Mr. Billy Fourwheeler, we are not gonna keep our current motor vehicle fleet running on biofuels, but wouldn't it be handy to have a nice, clean-burning biofuel to bake pizzas and cook brats with our EXISTING gas stoves?


Hans Noeldner

"'Green' cars are certainly a step in the right direction. But for those of us who are blessed with health and opportunities, the best steps toward a sustainable Earth are often…quite literally… steps!"

Sorry, Mr. Billy Fourwheeler, we are not gonna keep our current motor vehicle fleet running on biofuels

agreed as long as you use the qualifier "as of now" unless your crystal ball is clearer than mine.

There seems to be about 15% loss in this system. That seems a little strange. There is some heat missing somewhere and unless it goes up a chimney, I'm a little puzzled. If it does go up a chimney, it seems to me that more of the heat could be captured. Water heating represents about 17% of energy use in a normally insulated home.

So, a water heater powered this way would then cover the electric needs for lighting and appliances but not refridgeration or air conditioning. At 85% overall efficiency this seems as though it could reduce gas use for a system that uses primarily gas to generate electricity since the 40% loss from central generation would be partly avoided. For systems that use other thermal forms of generation, the fuel savings could be greater but gas use might increase.


What are the Laws of Thermodynamics?

1st Law—Energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy in the universe remains constant, merely changing from one form to another.

2nd Law—In all energy exchanges, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state. This is also known as the law of entropy.

3rd Law—It is impossible to cool a body to absolute zero by any finite process. This is actually more of a postulate than a law. In any case, it has little application to our discussion and is presented here merely for thoroughness.

Lots of luck.

[Rots of ruck in Japan and China]



I think the broader NG reticulation network is ultimately doomed. I've wondered whether NG could replaced with an alternative 'universal' gas. This is not so far fetched since the coal gas network was converted to NG post WW2. There would have to be a standard for heating value, nitrogen, carbon oxides, water vapour, premium components (eg methane, ethane, hydrogen) and presence of nasties like phenols. Standalone propane users (even BBQs) could convert to this new type of gas as would different kinds of CHP ..ICE, FC, Stirling.

However I don't think that scale is supportable. Sure Swedish trains run on sewage methane but that's not a whole city. Maybe the right kind of scale is something like a kibbutz combining a farm with community housing. CHP heats and lights the houses while the digester waste goes back on the fields.

any process by which we extend our energy and use it more efficiently is good.

U.S. thermal power plants alone throw away in waste heat as much energy as Japan uses for every purpose! That’s more than 20 quads. And that doesn’t even count the heat thrown away in industrial processes. Now the smartest thing to do with that heat for the next few decades is obviously either generate electricity with it or use it for heating buildings or industrial processes.

why waste power producing something else? imagine if the by manufacturing legos we produced pots and pans as a waste product and threw them out? you'd think they were nuts. why should power be any different.

why waste power producing something else?

Because the temperature of the hot and cold reservoir determines the maximum efficiency of the heat engine running between the two reservoirs. See .

It's waste heat because it's low-grade heat that can't be converted to electricty at more than a handful of percent efficiency or be used for space heating.

Direct carbon fuel cells can be much more efficient than a regular coal plant because they aren't heat engines. They are still experimental though.

I wonder about the value of this complexity, except in special cases.

Readily available NG condensing gas furnaces are 95% or so efficient. Extracting part of that energy and putting into electrical wires may have some value (more gas will have to be burned to get the needed heat), but is local winter electrical generation worth the added cost and complexity ?

In the typical case, I do not see it.


is local winter electrical generation worth the added cost and complexity ?

In the typical case, I do not see it.

I do.  If your system scores 50% efficiency, one house heating with an SOFC cogenerator can supply electricity to 2 houses heating with air-source heat pumps at 2:1 CoP, or 4 houses heating with ground-source heat pumps at 4:1 CoP.

One side effect of this is a simultaneous reduction in heating fuel requirements combined with a massive distribution of generating capacity.  The cuts in transmission losses and increase in flexibility (you could trade off with carbon-free wind or nuclear power when it was available) makes it a whole new ball game.

Engineer Poet said,
"One side effect of this is a simultaneous reduction in heating fuel requirements combined with a massive distribution of generating capacity. The cuts in transmission losses and increase in flexibility (you could trade off with carbon-free wind or nuclear power when it was available) makes it a whole new ball game."

I think that is exactly correct, and if we add in the recent increases in efficiency per cost of PV solar and the advances in Concentrating Mirror solar, you begin to see the distant outline of an energy structure that would be sustainable into the next century.
The main problem with solar that is beyond dispute is that it is variable, and that it's dark at night, thus calling for methods of efficient energy storage through the night and through cloudy periods.

A mix of backbone nuclear supported by widely distributed wind and solar along with Distributed Generation CHP running on small volumes of remaining fossil fuels (nat gas and propane are cleanest by far) and methane captured from waste, sewer gas and agricultural by product
creates a possible way to keep the lights on, the technology working, and the communication system (internet, radio and TV) system running.
It also offers the prospect of a grid based transportation system such as Alan Drakes electrified rail, and even individual electric vehicles and plug hybrids.

Everyone seems to be making great efforts to prove beyond a doubt that wind and solar can only be a marginal producer at the fringes. However we know that the potential imputs from wind/solar can be huge.
Until we accept that the alternative will have to be renewable we cannot begin to see beyond the depletion treadmill. The advantage of CHP,Distributed Generation and advanced energy storage technology is that they can make the grid reliable and renewables scalable. But it is in the end a choice.

A nation can make the choice to try to soldiar on using the old methods, trying to conserve their way out of the problem, getting poorer and poorer with each passing year. Conservation is important, but conservation alone does not produce energy. The limit is theoreticaly zero consumption, but nothing resembling a modern and civil state can be maintained at zero energy consumption, despite what some people may believe. Some nations are already showing that they are willing to use advanced methods, however, and are pulling ahead in the international competition for jobs, prosperity and decent living standards. The nations that scoff at advances in efficiency and laugh at attempts to advance technically are essentially volunteering to be the slave states to the nations that are moving forward. It really is that simple.


Case A - Three homes, each with 95% efficient condensing gas furnances

NG used = 3.16 units (3/0.95)

Case B - One home with CHP, the other two with air source heat pumps (2:1)

CHP puts 50% of NG energy into electricity (49% into Houses II & III, 1% lost), 47% into House I heat, rest into exhaust.

NG used = 2.12 units with a very small surplus of electricity generated for other purposes.

I see more insulation and better windows to be better investments,



The article says only 35% is available for heat so you are using 2.86 units of which 1.43 units are electricity so for 2:1 heat pumps, you heat an additional 2.86 homes, or effectively 3.86 homes. With the 3 units of gas you heat 4 homes, a 4:3 gain.

Compared to a 60% efficient gas turbine which discards 40% of the energy as heat, 3 units heats 3.6 homes. With 6% transmission and distribution losses, 3.39 homes.

For 4:1 heat pumps, 3 units of gas heats 6.72 homes with the fuel cell while the turbine heats 7.2 homes. Including 6% tansmission and distribution losses has the turbine heating 6.77 homes.

This seems a little counterintuitive but the leverage is in the efficiency of the heat pumps and so the small difference in the effciency of the fuel cell (50%) and the turbine (60%) is magnified by the increased gain from the heat pumps and using, or not, the waste heat becomes less important in terms of the final result.

Since heat pumps and cogen units are expensive, you are probably correct that better insulation gets us more at less cost. If the cogen unit costs less than the 4:1 heat pump system that would replace it together with the fractional cost of a gas turbine for servicing one more house, then it might also be a good thing to do since the turbine is only slightly better and one ensures that gas rather than coal is ultimately use for heating. But, it seems very unlikely that state-by-state regualtions would often allow a home to provide any non-renewable power to the grid and usually anything over net consumption is reimbursed at the avoided cost rate so it tends to be a bit of a money loser for the cogen plant owner. In the present circumstances, boosting the growth of renewables, making heat pumps easier to obtain by reducing heating requirements through insulation and encouraging renewable feed-in tariffs as a follow-on to net metering seems to me to be the best policy direction.


Air source heat pumps are quite efficient at warmer temperatures (say 45 to 50 F). Many American homes have a NG furnace and an air conditioner.

Replace the a/c with a heat pump, and make the NG furnace high efficiency. Install an outdoor thermostat to control switchover between HP & NG.

That simple combo would be hard to beat, and the marginal cost is relatively low for relatively long lived components.


I agree that there are many places where air source heat pumps make more sense than ground sources heat pumps. And, with better insulation, one can use a smaller unit, saving on the cost of the hardware. I would think that using renewably sourced electicity to handle the boost heating in this situation would be better than natural gas, but that is a minor refinement once the heat pump is installed.


The most efficient NG generators today are the combined cycle at roughly 50%. The rest goes up the stack as waste heat. With a combined heat and power unit, total efficiencies can be in the high 90s, although this is somewhat seasonal. Summer usage, however, isn't neglible, for there is still water heating.

Not only do you also save with less transmission, you need not build more transmission lines. In today's environment, this is a huge advantage. Further, localizing a portion of the electricity production makes the electric grid much more resilient to shocks. With today's electronic technology, DG is a no-brainer.

The biggest obstacle as I see it is that it breaks the traditional utility paradigm, and some resistance should be expected there. Solar power has already done that to some extent. DG will further the creative destruction.

Combined cycle NG units are about 6o% efficient.

Where co-generation use of combined cycle is possible, this is a clear winner (especially in areas requiring a lot of heating). But households are unlikely locations for this.

And power is much more than raw kWh, spinning reserve and load following are expensive and all of that is handled by the "old grid" while CHP skims off teh cream. Simply quoting MWh costs is NOT the full story.

Given the need for back-up in outages, I cannot see where CHP reduces transmission unless there are multiple CHPs that all agree to generate during peak demand. Existing transmission will not be torn out and scrapped because a dozen CHPs appear.

CHPs appear to be a useful niche product that should be encouraged, but a "third order" solution.


These ideas that squeeze a little more efficiency out of fossil fuels are desperate attempts to keep our current lifestyles in spite of global warming and peak oil, however they at least show a willingness to aim for a Plan B.

If the Olduvai Theory carries any validity and if Peak Oil really was 2005 (or any date in the next century) I think we are all missing the fundamental.

Olduvai mentions in passing that 4 BILLION people may have to be returned for recycling, once our free energy sources diminish.

Sure, the above lovely little co-generation units are good. However if we have 8 billion of them, it may be a different game.

The Russian and Scandinavian immigrants who came to the Prairies two hundred years ago understood precisely how to heat their Sod houses with limited resources.

The traditional Eskimos solved similar problems.

If we do not get serious about the way we waste energy, this historical cycle will definitely repeat itself.

We keep striving for energy savings and reductions of a few percent. It is like telling the condemned prisoner that the governor has postponed the execution for a few more days.

When do we start telling the people the truth, about what appears to be a scientifically verifiable reality. If we are wrong our ancestors will thank us that they still have energy available to use.

Do we understand that all our complacency will eventually lead to Legislation. "Legislation" is always made by the Powerful to protect themselves. Feudal overlords will again be the order of the day, and they will not be American.

These Overlords may well take the "First Night" privileges, and only their progeny will be allowed to survive.

50,000 units for $240,000,000 works out to $4800 each. Each unit generates only 2 kw of electrical power which works out to $2.40 per watt of generating capacity. If the 4 year lifetime can be achieved it works out over 25 cents/kwh. This is only a small fraction of the peak electrical power needs of most homes. The cost of batteries and an adequate inverter must be added or the cost of staying connected to the grid for a substantial percentage of you electrical needs must be paid for. 50% efficiency means it also generates 2 kw of heat. That is only about 7,000 btu/hr. This is not even close to meeting the heating requirements of a northern latitude home which means a conventional heating and hot water system must also be purchased. For many if not most applications this is a case of conversion efficiency working against the purchase and use of this product. For instance my old house in Michigan used about 5 times more energy in the form of nat gas than in the form of electricity. This was after adding new insulation and included an electric water heater and old inefficient air conditioning. For a new super insulated passive solar home this might be a good idea for meeting some of your electrical and hot water needs.

50,000 units for $240,000,000 works out to $4800 each.

That's a rather low volume compared to e.g. vehicle powertrains.  Prices are bound to come down as volume increases; the historical cost curve is a 20% reduction for each cumulative doubling of volume, so when production hits 1.6 million units (50,000*2^5) we'd expect price to be around $4800*(0.8^5) = ~$1600.

Each unit generates only 2 kw of electrical power.... This is only a small fraction of the peak electrical power needs of most homes.

Why would the unit need to meet peak demands?  These units are intended to be grid-tied.  If they were used in combination with a PHEV they'd provide substantial backup capacity, of course (and the excess generation capacity over average demand would allow the heating unit to supply net power to vehicles).

... $2.40 per watt of generating capacity....

Roughly half the installed price of solar PV, and the generation is counter-cyclical to availability of solar energy.

The problem of lifetime of this device is troubling. Currently it is only two years. What is it that wears out (platinum catalyst?) and how expensive is it to replace those parts?

SOFCs operate at high temperatures and don't need precious-metal catalysts to overcome activation-energy barriers.  The electrolyte material is something like yttria-stabilized zirconia, and the recent advances in thin-layer ceramic on metal screens (to reduce required operating temperature and increase durability over solid-ceramic designs) don't even use very much of it.

GE pitched a unit like this last century - to ship in under 2 years.

I'll believe this unit or any 'affordable' CHiP unit when I can buy one.

(Personally I'd prefer a stirling engine based one)

Hey thanks for the great blog, I love this stuff. I don’t usually do much for Earth Day but with everyone going green these days, I thought I’d try to do my part.

I am trying to find easy, simple things I can do to help stop global warming (I don’t plan on buying a hybrid). Has anyone seen that is promoting their Earth Day (month) challenge, with the goal to get 1 million people to take their carbon footprint test in April? I took the test, it was easy and only took me about 2 minutes and I am planning on lowering my score with some of their tips.

I am looking for more easy fun stuff to do. If you know of any other sites worth my time let me know.

Adrian, it might sound trite, but I had the pleasure of seeing Ed Begley speak recently about just that. He does have a book and a TV show called 'Living like Ed', I think which might be worldwide on Discovery Channel. Ed's famous around Hollywood for living green since the early 70s.