Carbon capture and storage

An alternative to CCS is to burn less coal. Combined heat and power (CHP) generation involves capturing the waste heat from power stations and pumping this hot water to neighbouring houses in district heating systems. Danish CHP plant is over 90% energy efficient

Carbon capture and storage (CCS) involves removing carbon dioxide from the combustion stream of fossil fuel powered generating plant and sequestering it under ground in water-bearing geological strata. The objective is to reduce or eliminate CO2 emissions from electricity generation with focus on coal-fired plant.

CCS has three main elements:

  • Capture of CO2 either pre- or post-combustion
  • Transport to burial site, normally by pipeline
  • Compression and burial in geological strata

The process involves large-scale engineering work, is expensive and uses a significant proportion of the power generated by the plant. The IPCC estimate that the energy cost is somewhere between 20 and 25%. In the UK the average efficiency of coal-fired plant is 37%, with 63% of the energy lost as waste heat. With CCS the energy efficiency drops to 30% assuming 20% of the power produced goes to bury CO2 rather than to power society.

An alternative to CCS is to burn less coal. Combined heat and power (CHP) generation involves capturing the waste heat from power stations and pumping this hot water to neighbouring houses in district heating systems. Danish CHP plant is over 90% energy efficient. Thus 3 times as much energy is extracted per unit of fossil fuel in CHP compared with normal plant fitted with CCS and this may equate to 67% reduction in coal use. Energy costs should therefore be reduced at national and individual level and CO2 emissions reduced by similar amount.

In Denmark, a certain CHP plant is also fitted with CCS. This is truly the belt and braces approach to environmental care.

Jevon’s paradox once again rears its ugly head. Governments must therefore legislate for energy efficient homes and appliances to avoid pointless waste of cheap energy that CHP may provide.

The obvious draw back with CHP is the engineering work required to build new plant and install district-heating systems in major cities. Given the political will, the Danes, Dutch and Fins have proven this is possible to achieve.

Conventional CCS is quite distinct from CCS-EOR (enhanced oil recovery). This process is related to CCS with the difference that the CO2 is buried in a mature oil field. Given favourable geology, the CO2 is miscible with the residual oil which may be mobilised towards production wells and which may otherwise have been left behind in the depleted reservoir. The primary objective here is to increase oil recovery. The additional oil produced may pay for the exercise though economics may be marginal depending upon the setting. The sequestered CO2 tends roughly to balance the additional CO2 from combustion of the extra oil produced.

Most existing CCS-EOR projects utilise natural sources of CO2 produced from geological strata and do not yet use CO2 from power generating plant. StatoilHydro’s flagship Sleipner CCS project also buries natural CO2 co-produced with oil and natural gas from the Sleipner Field. One report suggested that this CO2 may be leaking back to surface, but recent work by Statoil suggests it is not.

See also 2 stories by Rembrandt

CO2 Capture and Storage: The Energy Costs

CO2 capture and storage: The economic costs

Nice idea, but some parts of the world have a summer, and may even need more cooling than heating. I know about something called absorptive cooling (?), but believe it is a good deal less efficient than the current mechanical standard. Any thoughts?
On the other hand, or perhaps to shake the hand you first held out, I do believe that the whole notion of CCS is an enormous boondoggle, promoted as a plausibility expressly to cynically smooth the approval of coal-fired plants that have no chance of ever practically burying their wastes. Higher efficiency is indeed a better bet.

You're right, CHP is likely best suited to temperate climates. It is increasingly apparent that energy solutions are regional and that there is no one size fits all, though I do believe that energy efficiency needs to lie at the heart of decision making.

If policy makers would only ask at every juncture "is this an energy efficient solution?" then I think we would be in better shape.

Even in warmer countries, the hot water from CHP can be used for domestic and commercial uses, and I'm sure you could find industrial uses for it, for example timber mills. Just whack up the plant, set aside a couple of hectares for industrial buildings and then put out some ads asking if there are any would-be factory owners who want cheap hot water.

Could be good to use as a greenhouse with aquaculture like

Good place to stick the CO2 too.

Sure, you can pmp the CO2 into a greenhouse, but it is simplier to send the precious plant food straight it in the atmosphere and use it as a transport medium for carbon distribution.

Consider it as a donation to poor African countries, which could use increase in crop yields. All of the earth agriculture benefited from the increase in atmospheric CO2 concentration occuring in the past century.

Euan, I totally agree that energy solutions are regional. I think that as our economic situation shakes out, we will see that region solutions will be the answer to many of our needs - including access to financing, food, and some manufactured items. Using what we have access to locally, whether that is natural gas, coal, solar, wind, biomass just makes sense.

Absorptive cooling is the principle behind the "Einstein Refrigerator" and it is an impressive design, not requiring electricity. It was worked on by Einstein and his former student Leo Szilard. It lost favor when Freon refrigerators become so big. They are redesigning it for remote locations and making it more efficient:

It is certainly not unreasonable to use CHP to run cooling for industrial uses. Also, there are plenty of heating requirements even in hot climates (as has been mentioned). Municipal swimming pools come to mind (non-industrial), but hot water is one of the main requirements for bitumen extraction from oil sands...

CHP is a great idea. CCS is a bad idea (IMO), but it is a great boondoggle to get money from governments!


That looks like a scientifically-illiterate description of an Electrolux-cycle ammonia absorption fridge.

You can buy them today; if your RV has a propane/electric fridge, you already own one.

CHP in cool climates
There are many central energy plants in cool climates that provide chilled water. In the US there are most often found on college campuses but there are also many private and public utility providers as well.

Given the density, proximity and diversity of power and thermal loads to justify a central energy plant, there is often an off-take for heat - hospitals, assisted living,hotels, residences - in mixed use urban cores.

There is also the possibility to use life and safety generators (required for fire pumps, etc) as peakers that also drive absorption chillers to supplment standard electric chillers.

Nice idea, but some parts of the world have a summer, and may even need more cooling than heating. I know about something called absorptive cooling (?), but believe it is a good deal less efficient than the current mechanical standard. Any thoughts?

Adsorption chillers can use waste heat. Stuff you are throwing away anyway.

Absorption cooling is not necessarily less efficient than mechanical methods, but they do require a heat source. The site COP of an absorption chiller is less than that of mechanical systems. However, If you take into account plant inefficiencies and transmission losses, the amount of gas, for example, required to produce the electricity to run a mechanical system versus the amount required to run an absorption chiller is comparable. Of course, you can improve the total efficiency of mechanical systems by improving the electric grid, and mechanical systems, being driven by electricity, can use a variety of different 'fuel' source.

But with a waste heat source, or with a reliable enough renewable source, absorption cooling becomes desirable because of the ability to work with less heat than that required for conventional electricity production. There are systems in the American Southwest that use absorption chiller coupled with a parabolic solar thermal collector to provide cooling in the daytime, at a much lower installation and operating cost than can be had with solar-photovoltaics coupled with conventional direct-expansion chillers. There have also been pilot projects to test the viability of using geothermal heat sources to drive large commercial cooling systems.

So absorption cooling is really dependent on the application. If you have a cheap, clean, efficient source of electricity, modern high-efficiency refrigeration systems (particularly geo-exchange systems) will beat absorption hands down. But if you're working with a waste source of heat, or an endlessly renewable one, using absorption cooling would be more efficient than burning additional fuels to produce electricity to power a conventional refrigeration system. You also eliminate some redundancy in the system. You won't need all the extra electrical infrastructure necessary to meet the summer cooling load.

It really depends on your application. Conventionally, using absorption cooling is comparable to using mechanical refrigeration with the inefficiencies of the modern grid factored in. In this case, with a continuous source of waste heat, it can be an efficient and effective way to use the same heat source for both summer cooling and winter heating.

Also, keep in mind that systems working on the same principle are in constant development and I expect we'll see some pretty impressive efficiency gains in both conventional refrigeration and absorption cooling in the coming decade.

I hope this information was helpful.

Note that the claimed 20% energy overhead (reduced to 7% if ammonium-carbonate capture is used, IIRC) is for post-combustion carbon capture.  Pre-combustion capture can be far more efficient.

Also, CCS and CHP are hardly exclusive technologies; they can be used together.  Indeed, a historical business model is almost ideally suited to it:  the local gas works.  Instead of converting coal to producer gas, coal would be gasified (roughly 76% efficient), scrubbed, and the syngas steam-reformed to convert all the carbon monoxide to hydrogen:
CO + H2O -> CO2 + H2
The waste heat from the gasifier can power the required oxygen separation and provide the steam to the reformer.

This produces a hydrogen fuel stream and two side streams:  CO2 for sequestration, and H2S which can be dealt with in several ways (one possibility is to run it through molten copper to react Cu + H2S -> CuS + H2, then burn off the CuS in air:  CuS + O2 -> Cu + SO2.  React the SO2 with limestone to get gypsum and more CO2).  The hydrogen goes off to run remote CHP equipment, with minimal carbon emissions (some methane is produced in the gasifier and will go with the hydrogen unless it is removed and recycled).

Indeed, most CTL and IGCC plants produce both heat, and fuels/power.
The differences from the local gas works would be the scale, the reaction chemistry and the availability of low-ash coals.

This chart from the IPCC report posted by Rembrandt shows the distribution of energy costs.

Chart 1 - additional energy costs of carbon capture for different electricity plants, source: IPCC Special Report on Carbon Dioxide Capture and Storage.

Do you have links to support your claim of 7% - that seems lower than the compression costs alone - though I don't understand from the IPCC chart why the compression energy costs vary.

The ammonium-carbonate process doesn't require compression of any gases; the CO2 is handled as ammonium carbonate in aqueous solution, and can be pumped as a liquid.  It is liberated from the liquid at moderate temperatures, which can be done with low-pressure steam from the powerplant.

I did some digging and couldn't find the 7% figure again (it may have been superceded), but I did find this article which included this table:

The overhead for this process is under 9% per the table.

So what is the source of the ammonium? How much is needed and how is the ammonium carbonate disposed of?

Ammonium ion is formed by the dissociation of water in aqueous ammonia solutions:

NH3 + H2O -> NH4+ + OH-

Ammonium carbonate and bicarbonate are formed from ammonium hydroxide and carbonic acid:

NH4+ + CO32- + H+ -> (NH4)HCO3

2 NH4+ + CO32- -> (NH4)2CO3

Conversion of gaseous carbon dioxide to dissolved or precipitated carbonates reduces the volume and the required pumping work immensely.  Ammonium carbonate and bicarbonate can be dissociated into carbon dioxide and ammonia with heat at relatively low temperature; the references I found claimed that the heat input is around half that required for amine stripping, and the mass-loading of CO2 per volume of solution is much higher than for amines also, which requires less liquid to be pumped.

Great post. Thanks for reminding us how important waste heat use is to our future. If we are going to use coal, CHP is the way to do it.

An alternative to CCS is to burn less coal. Combined heat and power (CHP) generation involves capturing the waste heat from power stations and pumping this hot water to neighbouring houses in district heating systems.

What is the scale differential? E.g. I can plant root crops and get a much higher energy return than oil or natural gas, but the energy gain for society is limited. How much can CHP 'offset' if it were to be fully utilized? How much could it offset just using the 'low hanging fruit'?

Thanks for the post Euan.

This link has a chart showing share of CHP in various EU countries. Denmark, Holland and Finland stand out from the rest. Denmark with over 50% power from CHP in 2000.

Engineers and power generators will most likely say that CHP is impractical and no doubt there will be an abundance of NIMBI arguments as well. But these stats suggest to me that the issue is policy driven backed by political will. Sure, CHP will not be applicable everywhere. But in a world where most agree that energy efficiency needs to take center stage it is paradoxical that EU, UK and US governments are all planning to subsidise technology that goes in the opposite direction.

Euan - Nice post.

Let's not forget, however, that BIOMASS (woodchips, switchgass, etc) can be used as a feedstock in gasified combined heat and power systems as well and achieve similar efficiencies. There are two major advantages in using biomass (there are probably more - these are just off the top of my head): 1) from the standpoint of life-cycle analysis, the CO2 addition to the atmosphere is negligible and may even be a net sink, and 2) the actual biomass species used as a feedstock can vary from region to region - therefore cutting costs on shipping coal all over the place. Downside: 1) energy content of biomass is roughly a third to a half of coal and will require more feedstock for the same power output.

However the question to which Nate may have been referring is of utmost importance. Should we be building large plants to feed large population centers, or trying to install home units to do the same? For example, the newest pellet stoves can supplant directly oil boilers in the basement of people's houses and achieve efficiencies of {I think} over 90%. So there is a large vs small scale issue here.

But I was under the impression that the potential for wood, at least, is rather limited?

"...we have upper limits in expanding our use of wood for heating, and they are not too far from where we are now"

-- Nate Hagens, in

"Wir werden in der energetischen Nutzung des Holzes schon bald an unsere Grenzen stoßen"
(roughly, "We will soon reach our limits in the use of wood for energy")

-- Gerald Traufetter, quoting Udo Mantau, in Raubbau fürs klima (german)

Engineers and power generators will most likely say that CHP is impractical

Oh, it's quite practical, to a point.  I've suggested it myself.  But anything that relies on a fuel supply from depleting reserves or unreliable trading partners has a downside that's too often ignored.

and no doubt there will be an abundance of NIMBI arguments as well.

Anything that involves laying new infrastructure (like steam or hot-water piping) has much stronger counter-arguments than NIMBY.

Anything that involves laying new infrastructure (like steam or hot-water piping) has much stronger counter-arguments than NIMBY.

True, but it (NIMBY)can impose significant delays and cost via the planning and appeal processes that result. The unfortunate fact of life is that minority objectors usually make the noise whist the majority that are neutral or supportive sit back and enjoy life on the sofa.

Anything that involves laying new infrastructure (like steam or hot-water piping) has much stronger counter-arguments than NIMBY.

True, but it (NIMBY)can impose significant delays and cost via the planning and appeal processes that result. The unfortunate fact of life is that minority objectors usually make the noise whist the majority that are neutral or supportive sit back and enjoy life on the sofa.

Anything that involves laying new infrastructure (like steam or hot-water piping) has much stronger counter-arguments than NIMBY.

True, but it (NIMBY)can impose significant delays and cost via the planning and appeal processes that result. The unfortunate fact of life is that minority objectors usually make the noise whist the majority that are neutral or supportive sit back and enjoy life on the sofa.

Anything that involves laying new infrastructure (like steam or hot-water piping) has much stronger counter-arguments than NIMBY.

True, but it (NIMBY)can impose significant delays and cost via the planning and appeal processes that result. The unfortunate fact of life is that minority objectors usually make the noise whist the majority that are neutral or supportive sit back and enjoy life on the sofa.

Anything that involves laying new infrastructure (like steam or hot-water piping) has much stronger counter-arguments than NIMBY.

True, but it (NIMBY)can impose significant delays and cost via the planning and appeal processes that result. The unfortunate fact of life is that minority objectors usually make the noise whist the majority that are neutral or supportive sit back and enjoy life on the sofa.

Anything that involves laying new infrastructure (like steam or hot-water piping) has much stronger counter-arguments than NIMBY.

True, but it (NIMBY)can impose significant delays and cost via the planning and appeal processes that result. The unfortunate fact of life is that minority objectors usually make the noise whist the majority that are neutral or supportive sit back and enjoy life on the sofa.

Sorry, duplicated posts due to finger trouble! Pehaps someone can delete them as required.

Coal is not really appropriate for CHP but natural gas (turbines)is.
It is a matter of scale. CHP is usually less than 400 Mwe and district heating/cooling is a local affair.
It would be completely different than the central station power generation that we have now.
In Denmark in the winter a 400 Mwe CHP may get have a hot water demand of 450 Mwth while in the summer that would go down to maybe 50 Mwth.

Then what happens to the supposed efficiency?

40% of all US primary energy goes to making electricity and only 10% goes to space and domestic water heating(75% of natural gas).
Therefore CHP could at most save 10% of the primary energy and most of that would be replacing natural gas which emits half the carbon per BTU as coal.

So CHP for sure would be more polluting than CCS and wouldn't generate any more electricity.

The point is that focusing all energy into the production of grid electricity will still result in tremendous waste.
We need to reduce the production of electricity which is the greatest polluter(yeah, except nukes, nuke fans).

Of the 60% of primary energy that is not electricity, what percent is heat? As with many energy technologies, co-location of generation with consumption would help.

Note that the fraction of electricity that is used for AC could be heat-driven adsorption chillers, with a shifting of conversion of efficiencies in the power chain. How much of the 40% goes for A/C? I have seen several cogenerating physical plant models that are commonly used for "campus" style environments, with district heating ("steam") and cooling ("chiller") lines, and CHP would seem to fit that model quite nicely, though as you say at relatively small scale

It may be worth considering, if smaller cogen/CHP makes more sense, whether centralized coal gasification with remote combustion would work? Getting the power/heat where you need it while keeping the coal piles where land is cheap and using CCP to reduce pollution would seem to be key to efficiently utilizing coal for non-industrial applications.

But yes, higher efficiency usage in buildings would be a necessary and desirable companion to any production improvement.

10% of all primary goes for non-electric space heating and domestic water heating. I think about 10% of all US electricity goes for air conditioning which is 4% of all US primary energy.

Absorption chillers are ridiculously inefficient (with a COP of 1 or less) compared to electrical cooling (with a COP of 3 or 4). Plus you need cooling towers all over the place. Silly.

Small cogen like capstone would make a lot more sense than central station, but produce a lot more hw than power.

" Absorption chillers are ridiculously inefficient (with a COP of 1 or less) compared to electrical cooling (with a COP of 3 or 4)"

But the first COP is heat to cooling ratio, the second electricity to heat (or cooling) ratio and go down very quickly with lower temps; besides costs and reliability the thermodinamics is still in favor of abs chillers. Moreover, an abs chiller can be an abs heat pump with very high (real) COP even in the heating mode

if adsorbtion chillers are so inefficient then why is it the preferred method for large buildings and college campuses?

Inefficient doesn't necessarily mean bad idea, its an excellent idea if you got lots of low grade waste heat to dispose of.

If you compare ab/adsorption chillers with electrical heat pumps, it's only fair to include the efficiency of the electrical source conversion as well. A COP of 1 for free waste heat off a 40% efficient conversion beats a COP of 3 driven by the "expensive" 40% of that conversion.

Those steam absorbers are REALLY old school, back when universities used to have campus wide high pressure steam year-round.
Steam systems are almost always replaced with more efficient high temp hot water(HTHW).
They are almost all being replaced as lithium bromide has toxic chromates in it. The new absorbers are better but are very heavy and still inferior to the latest generation of centrifugal chillers.

I've thought for a while that coal would actually be a really good candidate for CHP. The main advantage for nat gas in terms of CO2 emissions in central power plants is that you do the Brayton and Rankine cycle, so you can get 60% efficiency,while with coal you can only do the Rankine cycle. That's why subcritical coal plants only get low to mid 30s in efficency (ultrasuper critical gets low to mid 40s while IGCC gets high 40s)

So basically coal gives you a much higher percentage of waste heat. Wouldn't it be better to save the nat gas for better purposes? The only plausible reason I suppose is that coal plants scale better (especially with emissions controls), but I could be wrong. Anybody else tell me if/why I'm wrong?

Actually, coal is a really bad candidate for CHP. For CHP to work, you have to be within a few miles of people's homes and workplaces. At longer distances the thermal losses from the piping are going to be a problem.

There are some things you don't want in the middle of a city and coal burning plants and rubbish incinerators are two of them. Think of the air pollution and noise problems. To be economical coal needs to be delivered by unit train. In the US that means 10,000 tons at a time.

What does work is natural gas. An NG turbine works great for CHP schemes. Even so, noise, architectural and air pollution issues can still cause problems. The noise problem is likely to be a big problem for very small scale schemes.

If you must use coal, the best solution may be to gasify it and then convert the syngas to methane. This can then be pumped into the existing gas network.

Presumably if CCS were happening, the air pollution at least wouldn't be a problem.

If there is less need for fuel then that fuel could be local biomass. Apart from no new net carbon additions to the biosphere the ash can be used in the garden as it lacks heavy metals. Coal smoke has nastier tars than wood smoke I believe which is why we can smell the difference between the two.

I think neither Sleipner nor Great Plains are valid models for CCS. CO2 scrubbing from NG via molecular sieve with a gas tight disposal basin next door is a lot easier than coal. For coal->EOR I understand the economics of the North Dakota operation are not generally replicable.

As for suburban block heating via CHP the built environment we have now is what we largely have to make do with. This also goes for ground source heat sinks, geothermal warm water and community gardens. Ripping up housing blocks to put in new pipes and boilers must be a limited option. If coal can be regarded as already sequestered carbon I think it should stay below the ground. Passive methods and HVAC of much smaller living spaces using low carbon electricity is the way to go.

I think the Russians already use district heating in many of their cities and from what I have read it isn't too reliable. I think that maintaining these systems might be expensive.

Some American cities like New York also have steam pipes supplying heat to commercial buildings. I'm not sure if that is CHP but maybe someone else knows?

In Russia, most of coal-fired power plants are called "heat and power central" (TETs). They provide electricity, heating and hot water. In summer months, when heating is off, they undergo maintenance, which may result in several days without hot water (maybe more in small cities, which rely on a single plant). In 90's hot water shortages in summer months were much more prolonged, so I installed electrical water heater in my apartment. But since then, never used it for longer than two days.

In Moscow (where I lived for 4.5 years) the warmwater outage in the summer period is 3 weeks. This has little to do with maintenance of the powerplants, but with maintenance of the underground pipes which are about 60 years old and mostly Carbonsteel.

Some disadvantages in Moscow that they turn on the heating when the daily avarege is under.... which means that you are cold for a couple of days in November, then when the wetter improves you open the windows for temperature control ??

Yes, the hotwater outage period depends on the state of the underground pipes. I live in relatively modern district, so friends from other parts of the city drop by in summer to have some hot shower. It's considered to be a norm.

And yes, the only way of temperature control is to open windows. It wasn't a problem when I had poorly insulated windows - it was always cold. But since I upgraded them, my apartment become too warm and I have at least one window slightly open throughout the winter, except for the coldest days.

Here is a list of US distric heating cogeneration plants.

The Grand Rapids district heating system gets part of its energy from a trash fueled power plant about a mile from downtown. In very cold weather the system needs a gas fired boiler to meet demand. The main heating loop is over a century old and the sight of steam blowing out a manhole cover at different points is a daily event.

“Carbon capture and storage (CCS) involves removing carbon dioxide from the combustion stream of fossil fuel powered generating plant and sequestering it under ground in water-bearing geological strata.”

I like the idea of using CO2 for enhanced oil recovery, I have seen production data that indicates in the proper setting it enhances production extremely well as a tertiary production enhancement. However if one were to try to sequester it in water bearing strata it would need to be strata that would likely never be tapped for the water as CO2+H20+Pressure=>H2CO3 or carbonic acid, which in enhanced oil recovery fields can add additional difficulties to the engineering of development in the form of in-field drilling. And in a world where water starved regions may turn to deeper briny formation water to be cleaned up and desalinated for drinking or agriculture, if we sequester CO2 in it liberating the CO2 would be necessary to utilize that water for any other purpose at a later time.

The fact that H2CO3 is a byproduct of sequestering CO2 in water bearing formations, careful geologic assessment of any potential injection site will need to be made to make sure that the CO2 or H2CO3 will not have an opportunity to migrate. This may limit its application to only suitable sites, or may require shutting down some existing plants and moving their operations to more suitable locations if the economics indicate that it is simpler to build a new plant than transfer CO2 in a pipeline as CO2 is an acid gas that is highly corrosive to metal tubulars, and a CO2 line headed through a town could be disastrous if a leak went undetected. CO2 is heavier than air or at least the bulk of air, with a molecular wt of 44, while O2 is 32 and N2 is 28. If a leak of CO2 from a pipeline or outcropping of the sequestering formation were to occur in a confined location, anything from a stream bed to low lying town, it could be highly dangerous.

I’m not saying that it isn’t worth doing, however here in the United States we are told and sold on ideas as being a lot easier and simpler than they really are. Anyone can be for an idea only being told its benefits, but when you read them the fine print it changes their perspective significantly. CHP may be the way to go as anyone is for cheap heating and hot water, not everyone will want a pipeline of potentially hazardous gas running through their town or a potential significant drop in the pH of their well water.

Carbon sequestration sites are really DEEP underground way below groundwater. Today, CO2 is pumped 4600 feet below the surface of the Weyburn oil field (carbonate rocks which can absorb lots of CO2). I think the government minimum for CCS is +2500 feet deep.

How many oilfields are under cities(besides LA)?

Hi EWC and Majorian,

For CO2 to be truly effective in EOR projects, it has to be under sufficient pressure to become miscible with the oil it is to sweep out of the formation. The one "CO2 flood" planning this that I am familiar with would require a surface pressure of 3,500 PSI, and they do not yet have a permit to inject anything at that kind of pressure. Simple reinjection of CO2 at formation pressures does not work and does cause the corrosion problems that EWC references.

There are other possibilities, however. There are many large oil fields which have already undergone sharp declines, with many potential locations for non-EOR injection, thus at lower temperatures. If the wells, before plugging, were tested for mechanical integrity, much the same way as is required for salt water disposal or injection wells are, and if suitable, were used to inject the CO2 until some reasonable pressure was realized, it would be practical. Just as theefficiency of the CHP plant makes the overall project possible, the same would be true with such CO2 injection into wells which were going to have to be plugged anyway. And, as is the case with CHP, it is something which should have been done in the past and not just now. Simple technology and existing facilities.

Majorian: The Barnett Shale lies under Ft. Worth, if you consider it a major city. They don't have a downtown sewer plant anymore, and that should improve their status.

I'm not all that keen on CHP, especially if it used to greenwash the usage of unsequestered coal. CCS is till a ways in the future. Some experimental methods are less energy intensive then your figures (at least one was mentioned above), but we don't know if any of these methods will prove to be practical. I'm hoping we eventually develop some form of CCS, and use it with biofuels, for a net carbon negative operation. But, this is decades waya, if ever. In any case, except for new construction, and the occasional site where a power plant can be co-located with an industrial plant which consumes low grade heat, I don't think CHP is practical. I don't know how costs compare, but retrofitting high efficiency insulation, and perhaps air source heat pumps is probably more economical. And for those cases where we need significant inputs of low grade heat for industrial processes, solar thermal plants can be used. Note, that the cost per MWhrT is much less for low grade solar thermal, than for solar electric. And industrial scale usage for CHP, might be co-located with Nuclear power as well.

Some of the utilities in the Midwest are continuing to experiment with algae and the progress may be a little faster than you anticipate.

Research into CCS has been skewed by coal-fired utilities' desire to preserve their capital investments on the one hand, and oil companies' interest in EOR on the other. The result is a 'bolt-on' technology that can be added to existing plants, but which makes no economic or environmental sense.

Some companies have tens of billions invested in plants that must be scrapped and replaced with completely new cycles like ZECA or supercritical water oxidation, if CO2 is to be sequestered efficiently.

The question is how to pay for this. Is it fair to just legislate change? Is cap-and-trade a sufficient motivation? Can domestic industries tolerate higher electric rates?

I think a federal 'bailout' would have been the most fair and effective method. Matching funds for new plant investments, decreasing over time to encourage early action. Unfortunately, the banks got in line first, and such a policy now would require pretty serious committment.

Thanks Euan, for pointing up how much waste heat coal power generates. Waste heat from four separate small coal power plants heat the university, downtown area, army post and air base in my neighborhood. I believe the heat was a big reason why the local coal mining company bought the badly neglected downtown power plant several years back. 14000 heating degree days does make heat an in demand local product, not to mention the air quality issues waste heat use alleviates by eliminating the need for some oil fired furnaces.

Locally these are all small plants with limited pipe networks, do you have any information on how large it can be efficiently scaled?

I think one of the objectives of CHP is to have it small and local - though if coal is used, proximity to rail is a clear advantage. In the Dutch, Fin, Dane link there is a map showing distribution of decentralised CHP in Denmark.

Another advantage of small decentralised plant is that it can be used in multi-fuel combustion utilising municipal waste, bio-mass or whatever is around to burn that may otherwise be left to rot.

Denmark has done an amazing job decentralizing its CHP. That is a lot of heat capture.

Given the success in europe with smaller scale biomass and waste to energy projects, it seems that we should be also able to figure out a way to scale down a coal plant. This could well be a more efficient option than using CCS to burn this dirty fuel. The energy density of coal is so much higher than biomass and it does not need to consume extra energy as does a biomass plant to burn off the moisture contained in the fuel. These factors alone would tend to make coal combustion considerably more efficient and cost competitive than burning biomass. Yes, there will be a need for SOX and NOX removal systems that may not be as applicable in a biomass plant but otherwise most of the other material handling systems should be similar if not smaller in scale than for a comparably sized biomass plant.

Here is a post on cost effective pollution control systems for small coal plants.

It would seem that small scale coal fired CHP systems deserve more consideration.

You might be interested in this

Describes using micronised coal in slow speed diesel engines for 50% thermal efficiency using <100MW sized units for more suited to CHP. Also cooling water is less of an issue when smaller units are used, also the start up and load following times are much higher than steam units.

Small scale CHP is a technoligical and economical frontier since large scale CHP already is efficient. Both the large scale and small scale trends are active in Sweden. New district heating networks are built in micro scale with heat only plants and small scale CHP and both large and small district heating networks are interconnected and the large scale networks get new CHP plants that mostly are fired with waste or biomass plus some natural gas ones.

No doubt CCS is technically possible at a small scale. But I can't see it being able to be scaled up to make a significant difference to carbon emissions.

It costs energy to capture at the source,more energy to compress to a liquid,more energy to pump through an energy intensive pipeline,probably over a long distance,to an underground storage of doubtful security. It is a no brainer.

My conclusion - CCS is a diversionary tactic by the coal industry in order to continue business as usual - aided and abetted by governments in thrall to big business.

My conclusion - CCS is a diversionary tactic by the coal industry in order to continue business as usual - aided and abetted by governments in thrall to big business.

First up, I have to say that CCS is a crock. If so, why are we bothering?

Well, that brings us to the second point: government is not merely in thrall to big business, but in thrall to the public.

Here Down Under we're very reliant on coal and our idiot PM is promoting "clean coal", so I have a bit of perspective on this. Some have asked why, if it's so crap, do the US President support it? What do they know we don't?

What Obama knows is that time is short, and whatever he wants to put in place it's no use unless it's continued by later government. The reasoning goes like this,

1. People need transport (of themselves and the things they want to buy), heating/cooling (of themselves, their water and food), light and entertainment.

2. These things all require energy, most of which is currently got using fossil fuels.

3. But fossil fuels are finite and won't last forever, and also they produce pollution. Oil is on the way down in production, gas will be around 2020, and coal around 2040.

4. Therefore, the world must burn less fossil fuels, and eventually burn none.

5. But if we burn less fossil fuels, we have less energy.

6. So we must either make do with less energy, or find different ways of getting our energy.

7. In the US, Australia etc, no-one will get elected on the platform of "no more burgers and SUVs", so the "use less energy" isn't an option.

8. Renewables and/or nuclear? It takes several decades to transform an energy sector from one source of energy to another (simply because it takes years to build big things), and in those decades climate change will hit us hard, oil and gas will run short, but probably not coal.

9. The several decades required for transformation can become a few decades if rather than building entirely new power plants, we just alter the current ones.

10. Altering gas and oil-fired stations is pointless since the supplies of those are going to run short within two decades - so if you build a new oil or gas-fired plant today, you couldn't guarantee it'd be fuelled for its whole 40 year lifetime. It might still be worth to build the thing, just not with any extra doohickeys on it - like CCS.

11. That leaves altering coal-fired stations, while slowly beginning the work of building out renewables and/or nuclear.

12. So Obama believes in "clean coal" because the only alternative is asking Americans to consume less while the country builds up renewable generation over decades. Carter tried that and got one term; his successor removed the solar panels from the White House roof. You might be happy to lose office if your policies live on after you; but to lose office and lose the policies is pointless.

There is not much chance that "clean coal" will be anywhere near as clean as we need it to be to avoid catastrophic climate change, and anyway it doesn't solve the problem of coal being finite. But it's the only chance the US (and Australia) has, unless we just consume less.

Now, it is possible to ask people to consume less. It's worked for water here in Australia - a combination of advertising, progressive pricing and regulation are very effective in reducing consumption. But it takes very courageous leadership in Western society to suggest reducing overall consumption.

And anyway our "leaders" are not leaders but followers, they follow public opinion. That's why there are laws about nipples on television and so on, because people organise letter-writing campaigns.

Not many people write to their elected representatives asking them to help us reduce consumption. As Monbiot wrote in Heat, "nobody ever rioted for austerity." Some people have decided to prove him wrong but it's hardly a world-sweeping movement quite yet.

It would take a generation or two to transform the way we transport, heat and cool, light and entertain ourselves - new power plants, railways and so on. In that generation there must be clean coal, or there must be austerity.

"Austerity", of course, is a relative term. We're not talking a Third World life here; but no more driving a mile for a bottle of milk, no more four pounds of meat a week, no more airconditioning except for infants and elderly, no more open refrigerators at the supermarket, no more $100 cross-country flights, and so on. Conspicuous waste would have to end.

Consider your own lifestyle, and ask your friends about theirs. Consider this article offering eight simple guidelines for reducing your emissions to around a tonne of carbon dioxide annually - a 90% reduction from the Western average. As you read down the list, feel the excuses "but I can't because... others can, but I can't..."

Every person has very good reasons for every bit of their consumption and waste. Nobody could possibly reduce. "It's too cold to bike, I'm too fat to walk, it's a hundred degrees here and I'll die without aircon, but a man must eat lots of meat it's in our genes, my family lives in another state and they're very dear to me that's why I moved away from them so I have to fly" - and so on.

Now multiply that resistance to change by millions of voters and tabloid media tearing into anyone bold enough to suggest genuine change, throw in an economy in trouble just to spice things up - and thus you get "clean coal" and this CCS nonsense. Anything else would be too radical. Even without millions in bribes - er, political donations - from big business, this is what our governments would be offering us.

Because we the public don't want change. That's why we're keen on things like electric cars, CCS, hydrogen, and so on. We're hoping to get results without any work at all. Actually working? Radical!

Not just down under. Here in UK the Prime Minister was talking positively about CCS just yesterday on national radio. He needs to read TOD.


He talks positively about the economy as well viz Britain is well placed to weather the economic storm! AND we need to restore growth as soon as possible ......Were doomed

Well put. I think the great irony in all of this is that most of the things people are so resistant to give up never really made them happy in the first place. People are so adamant about maintaining our precious lifestyle, yet I feel they never consider what good it really does for us. Most surveys related to happiness place northern European countries at the top of the list. The United States never seems to crack the top ten despite our wealth and ability to buy just about anything we desire. I wouldn't exactly consider these surveys to be particularly reliable (cultural differences and such), but I think they at least show that energy consumption and consumer goods do not equal happiness.

"In the US, Australia etc, no-one will get elected on the platform of "no more burgers and SUVs", so the "use less energy" isn't an option."

I agree with you, in principle. So the solution seems to be to tweak the market such that the burgers and SUVs become so expensive no one will buy them. There are also certain fundamental limitations that come into play. New research suggests that the US does not have nearly as much easily accessible coal as we previously thought. If it is only recoverable by expensive means, then the cost inherently goes up. What's more, with plans by many states to begin construction of projects to gasify coal and then use the gas to produce synthetic transportation fuels to offset America's petroleum imports will only increase the demand for the mineral and, therefore, the cost. We are entering a period where we must input more energy to maintain our lifestyles.

My point is that austerity is inevitable. The limitations of our world will enforce them for us. So the task of our leaders is to engineer our societies such that we still have a high quality of life, even if we don't have as much stuff.

But the argument may be moot. I think the credit crisis will cure America of its large houses and vehicles. No one can afford a $300,000, 2500 sq. ft villa in the suburbs, nor can anyone afford to finance and fuel these $35,000 behemoths that once ruled America's roads. I live in New Orleans and am in the market for a new home. Probably the largest house I could afford to finance would be an older home no more than 1200 sq ft., half the size of some of the "modest" homes being built out in the far-flung suburbs, most of which have For Sale signs up in front of them.

Kiashu (aka Diogenes in a tub),
Has it ever occurred to you that you bear no resemblence to a normal human being?
IOW, you're not helping.

I continue to think that CCS is a very bad idea. All of that CO2 underground will eventually find a way out. If it gets out suddenly, then that means sudden death for anyone living nearby.

No, CO2 underground won't eventually find its way out.  Many rocks react with CO2 to form solid carbonates, fixing the CO2 for geologic time.  Slow seeps are no safety problem; there are springs with effervescent waters, and they have been prized, not shunned.

District heating with waste and garbage as fuel works just fine in Switzerland, and makes sense.

However, building coal power plants to provide heat in addition to electricity is probably impractical due to the scale of such plants, and the lack of demand for heat. The only role of CCS seems to be allowing new coal plants to be built, with the promise that *one day* CO2 will be captured. I don't believe a word of it. Currently, many large-scale CCS pilots are being scaled-down or canceled altogether, so even the beneficiaries don't really support it fully.

Reducing the need for heating (insulating older buildings and much better building codes for new buildings), and providing the remaining heat with heat-pumps and solar thermal, is the way to go.

Photovoltaics and wind do not produce waste heat. Anyone know if that's an advantage, from the investments /profitability pint of view?

Photovoltaics and wind are not 100% efficient, so I would think that some of the energy that is not absorbed or used is in fact dissipated as excess heat (engine heats, solar panels heat). So they do produce waste heat, but it is harder to capture as it is not concentrated as in a coal power plant facility.

An alternative to CCS is to burn less coal. Combined heat and power (CHP) generation involves capturing the waste heat from power stations and pumping this hot water to neighbouring houses in district heating systems.

Why is this presented as an alternative to, instead of an addition to CCS? I think this presents a false choice. No choice needs to be made, both technologies could be used for the maximum benefit.

In the UK I don't think we will be able to afford to import all the energy we need for much longer - and I find it difficult to condone that we waste so much. I think it is better to chose conservation and efficiency over more waste.

Sterling is down 25-50% in a year so I'm with you on that. Notice how the US has seen Gas prices fall from a shade under $4 to under $2 but the last time I looked UK Petrol was ~£0.9 compared with £1.25 last summer.

I think the way this will pan out is that the UK will be exposed to a triple whammy:

1. increasing NET imports as NS output declines
2. increasing payments on those imports as Sterling takes another nosedive
3. PO driving the Global price up.

Its not going to be pretty but damn, we do waste a helluva lot of Energy...


I adjusted my diet last year, shedding pounds.

Down almost 2 stone in 6 months.

Exactly, maximize your efficiency where you can. But carbon capture is the only way to be a good citizen of the world while you do. Now I don't think the UK is going to be ready to be a climate refuge for millions of people that will suffer from drought and agricultural disruption if we continue with BAU.

One aspect of this that's being overlooked is the ability of low-grade heat sources for cooling. Remember your granddad's old gas refrigerator? The same principle can be applied for HVAC.

By utilizing absorption chillers, the hot water could be used for cooling as well, thereby providing complete energy needs, even in warm climates where the major energy load is from cooling systems. This isn't as efficient as using the hot water directly for space heating, as absorption chillers still require cooling towers to dump waste heat into the atmosphere, but you eliminate the electricity consumed by refrigerant compressors by using waste heat to power absorption chillers. The great thing about absorption chillers is they don't care about the source of the heat. Pilot plants exist using hot water from solar, produced by waste gases from micro gas turbines, geothermal heat, and in some cases, a combination of any of the above. Furthermore, in hot climates, commercial buildings accumulate enough solar radiation and internal heat to require cooling for most of the year.

Fundamentally, if you have a reliable source of hot water, you don't need anything else for space heating or cooling. So district CHP systems are great for this sort of thing, you just need to site them close to areas where the demand is. Retrofitting some of our major urban centers with this sort of technology could go a long way to cut our electricity consumption.

I really find it hard to get my head round these things and I know its a pretty basic principle. Have you any good links?

(I understand how a refrigerator works and I have just got my head around how ground and air source heat pumps work to heat -but now your saying you can use heat to cool? Lost again)


Here's a starting point (lacking good diagrams for the ammonia cycle):

90% to 98% thermal efficiency? Did they repeal the Second Law of Thermal Dynamics in Denmark? Do they heat Danish homes during the summer too?

I think it's only the peak winter (maybe very long in DK) generation

I suspect, too, the efficiency in electricity generation goes down at least slightly in cogeneration mode (though the total efficiency results improved, if the heat is really used)

I doubt that much heat is being put to end use. They may have a 90% plus thermal efficiency at the plant (some modern gas furnaces for homes get 99% thermal efficiency) but you're going to have losses piping that much heat around town.

Community CHP could be a really good combination with district solar thermal, and by lowering the amount of fuel required it makes it more suitible for using a biofuel (biogas from sewage and crop digestion) to supplement the fossil fuel. The economics should work better for a system of this size maybe 20-50 homes. If the properties are to be rented, then the extra capital costs can be paid off set against external energy costs.

I am actually using heat and power from the above mentioned CHP plant.
Here are some figures for you.
During the last 3027 days I have used 82,49 MWh of heat delivered in the form of 1702 m3 of hot water.
That is 562 litres/day.
The power to pump this water is miniscule considering the energy this water delivers.
I get 49,64 KWh/m3 or on average 23,4 litres/hour

With regard to waste heat in the summer, the solution is to have enough users of heating. In the summer we still need hot water, and hot water uses extremely much energy. In the wintertime they actually need to reduce electric efficiency to get enough hot water. At these times they probably should use heatpumps...

I use 10.188 KWh/year, wich is twice the energy I use in the form of electricity. A CHP plant with lots of customers like me would give a surplus of power, or at least get good use of the heat during summer.

With regard to the construction, I always get the picture of these giant cooling towers at other powerplants while they heat up their homes with gas next door. CHP is definitely a low hanging fruit.
Constructing these coolingtowers is such a waste.
By getting more people connected to central heating it will also be easier to deploy large scale heatpumps to use surplus electricity on a windy day in a costeffective way. The installed waterbased system of district heating can be used as a massive buffer of energy.

A Lithium battery is 230KWh/m3. Water is in my case 46.
The Li-Ion battery might be better, but water is cheaper...
I dont think I know better ways to store energy as dense and cheap as hot water.

In order to understand the exact efficiency, unfortunately the figures are incomplete.
We should understand how much fuel (coal, of given lower heat value) is burned in the plant in a given time versus the thermal energy and electricity delivered in the same time. I expect that value can be very high, at least in the winter, but not maybe > 90% (expecially if you consider only end user consumptions)

Moreover, I' m not sure that even in a high effcient CHP we can avoid a cooling tower at all

Thanks Rune - interesting. So you're saying that the water in district heating can be used as an energy store / buffer to help smooth out issues with irregular power supply?

Do you know what the water temperature is on the cool side of the loop?

The push for CCS is easily explained. It means more coal, oil, and gas will be sold to power plants for every kwh delivered to customers.
The most reliable way to store carbon is to leave fossil fuels in the ground. Number two is negawatts which reduces the need for electricity from all sources. Number three is charcoal production from crop and forestry waste. The process of charcoal production emits gases and liquids which not only heat the feedstock but can fuel a CHP system. A drawback may be the size limit of each agrichar system is around 20-30 megawatts using biomass collected within 20-30 miles of the power plant. It would require a large increase in the number of power plant with the need for a large increase in the number of employees which would increase the cost of power.

What happens to this formula when we make all the houses passively heated and cooled? Is that not the most CO2 friendly way to heat/cool buildings?

So with CHP we are then burning fossil fuels to heat buildings we can heat directly with passive solar. Does not seem to be the answer we need.

I don't think we are about to knock down and rebuild our whole housing stock. We will be forced to work around and slowly adapt the existing built infrastructure.

There's no need to knock anything down.

Most houses can be retrofitted to get most heating via passive solar means. Adding low-e windows, perimeter insulation, and replacing wall-to-wall carpet with tile or some other heat storage material will do most of the trick. Passive cooling comes from shade trees, insulation, and ventilation, relatively simple and low cost ways to retrofit a home.

Back in the 80's I lived in Winnipeg in a house built in the 30's, but with some relativity minor additions of extra insulation and double-glazed windows. Heating costs during a Canadian prairie winter were minimal. If that house was given the full treatment, I calculated that it could have come very close to needing zero heating apart from the winter sun.

I agree, I also lived in Winnipeg in 1980's and insulated a 1903 built house, basement, double glazed windows, attic insulation, using a 15 year low interest loan paid off on electric bill.

Great topic for a post - the level of waste heat from our thermal plants is tragic.

Two UK things for comment:

1) I'd like to highlight the report Poyry produced for Greenpeace:

Coming from the other direction they looked for opportunities to generate electricity at existing sites requiring large thermal loads. I think 13GW was identified as mid range possibility = approx 20% UK current peak req. This technology is in use at Immingham (approx 730MW initially -

expanded by another 450MW -

with multi fuel and flexible configuration options).

A site identified with potential of approx 2GWe potential was Pembroke where recently 2GW (5x400MW) of non CHP CCGT plant has been approved:

This seems a significant missed opportunity - would welcome informed views. Imagine industrial CHP far less costly than nuclear and much more quickly deliverable (Immingham initial capacity cost quoted at £350m for 730MW vs. approx £3bn for 1.6MW EPR). Oil refineries/petro chems are the big thermal users so may be there are PO considerations but imagine we'll be refining for 10 years more at least - and if the plant is multifuel compatible it can move with the times? Is it possible to relocate and redeploy major components if design is flexible and modular from the outset? It's a while since I read the report but it all seemed resaonable.

2) In the US I saw reference to a CHP retrofit to an 800MW coal facility replacing cooling towers. I've lost the reference and haven't refound it but I think this is something of value. A study similar to the Poyry approach could evaluate existing plant and surrounding development and planned development to see if CHP retrofit would be viable. For major new housing build near thermal generating plant this would seem a good approach. For existing built environments a CHP masterplan could be drawn up possibly using opportunities to coordinate utility works with opportuniities to install heat mains. I know the latter is a big ask but with the right legislation and political will it should be possible. For example London has had a CHP/decentralised study produced by the London Dev. Agency:'s_Carbon_Footprint_FULL_Low_res_FINAL.pdf

Would be interested in Engineer Poet's model above in this context?

UKCS production of oil and gas appears to be in decline so we really need to get serious about conservation and more effective use.

UK Gov are consulting on Heat and Energy Saving Strategy until 8May09:

District Heat and CHP are covered in Chapters 6 an 7 - Get your comments in!

UKCS production of oil and gas appears to be in decline so we really need to get serious about conservation and more effective use.

The government is committed to energy efficiency and so that is why they are sponsoring CCS which will reduce the energy efficiency of already inefficient power plant. Very prudent I'd say.

CCS Demonstration Competition

Just think, we can use that electricity from the CCS to electrolyse hydrogen and use it in internal combustion engines!


I think the BOE may issue some highly leveraged energy derivatives to tackle the problem.

Would it not make more sense to reform the hydrogen and use the steam in in-situ gasification?

Just out of curiosity, what happened to British coal production in 1985?

A big miner's strike. Basically it was Thatcher's "there is no such thing as society" (only individuals) vs the miner's socialist unionism.

The miners lost.

Its worth noting at the time there was concern about acid rain falling on Scandinavia and since UK coal is sulphur rich, it was a part of the problem. North Sea gas was coming along and a decision was made to shut down large swathes of the UK deep coal mining industry in favor of switching to nat gas and imported, cheaper low S coal.

The question now is whether we will ever be able to re-open deep mines and persuade workers to go back to Victorian working conditions that they fought to defend back in 1984.

Um, I don't think Thatcher's motivations included worry about acid rain on some Nordics...

"Great topic for a post - the level of waste heat from our thermal plants is tragic."

Couldn't agree more with that statement and until we address this we are missing a huge energy supply opportunity.

A Japanese company called Xenesys produce a system that can generate electrical energy from waste heat. They use a 'Uhera Cycle' double stage turbine method that is more efficient than a Rankine cycle single stage method. The diagram on their site looks quite complicated to my eyes with multiple heat exchangers, turbines, etc. I.e. its going to cost.

TOD is long overdue a post on OTEC technology Btw.

Regards, Nick.