Mr. Adams’s claim about “an awful lot of diesel, coal, and natural gas” being consumed by micropower is addressed in Part One of my response to David Bradish’s post at http://neinuclearnotes.blogspot.com/2008/06/amory-lovins-and-his-nuclear-illusion_05.html. Mr. Bradish was referring to the fuel mix of the non-biomass cogeneration that our “micropower” database combines with renewables other than big hydropower. As I stated, cogeneration does burn some coal, but not much. The mainly gas-fired cogeneration fuel mix is unknown in detail but does include some coal, chiefly in China and India (where gas is often available), and to some extent in Germany, all aided by coal subsidies. USEIA also reported that 18.7% of the U.S. cogeneration in its partial database for 2006 that burned fossil fuels was coal-fired, including culm or waste coal. However, even coal-fired cogen greatly reduces the carbon otherwise emitted by separate production of power and heat, because it displaces the separate fueled boiler(s) otherwise needed to produce the heat that cogen recovers. The resulting carbon saving is smaller than for the predominant gas-fired cogen, let alone for renewables, but is still substantial. I hope soon to receive updated cogen data casting more light on the fuel mix, and if I do, will post it to our micropower database at http://www.rmi.org/sitepages/pid256.php#E05-04.
So Amory Lovins admits that, so far as the supposed carbon savings from "micropower" are concerned, he really doesn't know what he's talking about... but he might find out soon?
As I pointed out in the past, Lovins' definition of "micropower" makes no sense and only serves to obscure the fact that Lovins is in practice essentially shilling for fossil fuels, his (perhaps earnest) claims to the contrary aside. All that's new is that Lovins is admitting he doesn't actually have the data to support his claims.
To paraphrase Lovins: "Pay no attention to that man behind the curtain."
ReplyDeleteEven Lovins cannot (can he?) claim that electricity produced from cogen is as efficient as specifically-designed modern electrical generation. Combine that reality with the efficiency of even air-coupled heat pumps and Lovins' claims on the relative merits of cogen require substantial justification.
ReplyDeleteFor example (all figures illustrative but reasonable), if we can get 40% electrical generation efficiency, (60% losses) out of a coal burner power plant and a heat ratio of 3 on heat pumps, that plant can be effectively more efficient than a cogeneration back-pressure steam turbine which gets 10% electrical efficiency and 70% heating with 20% losses. We could use 25/40 of the dedicated electricity generation in heat pumps to see the output of the dedicated electrical station above the cogeneration system for both heat and electricity.
Even if my figures are overoptimistic, it is clear I think that the gap (if any) is not as wide as the cogeneration boosters would want us to believe. Cogeneration is by no means an efficiency panacea.
Shorter Joffan: Electricity is a lot more useful than heat.
ReplyDeleteRight on! I personally think a serious analysis of natural gas cogen (not even coal) cogen versus nuclear+geothermal heat pumps in terms of overall cost and environmental externalities wouldn't end up looking very flattering for Lovins...
ReplyDeleteWhat I find so odd about Lovins passion for cogen is that there just isn't that much demand for low level waste heat much of the time. What is, say, South Carolina going to do with cogen central heating in July? Even if you can capture a very large fraction of the available heat, it just doesn't seem very... useful.
Could warmer countries use cogen heat to desalinate water?
ReplyDeletePotentially, but that's a much more technically demanding process than just using it for domestic heating. (Also, you need a body of salt water to desalinate, so it's not that attractive for, say, the interior of the southeast US.) It's been done, though--the Soviet BN-350 in Kazakhstan used nuclear process heat to desalinate water in addition to generating electricity.
ReplyDeleteCo-Generation has it's advantages in that you can get around having to deal with the loss of a thermal engine for some of the power, which can go right to heating. Cogeneration works well when you have a big need for heating, such as a city with a district heat system or if you have a power plant that's reasonably close to a city or even a couple of universities, military bases, big factories or whatever.
ReplyDeleteHowever, if you want to use it for heating out in the 'burbs or something like that, good luck! That's where you need the whole microgeneration bull, and that's at least as much trouble as it is worth.
Central production tends to be more effecient and economical. This rule applies to all things. People eat from big industrial farms and nobody starves like they would if we all had to keep gardens to stay alive. Factories produce more product at a lower cost than craftsmen at home. Big centralized turbines and transformers are more effecient than little ones and it's cheaper too.
The idea of a little put-put power plant on every street corner is not new. Edison invisioned such a system, but larger systems were so much more economical that the low-voltage local concept largely died. Still, in the late 1800's it was not uncommon for a wealthy person to want electricity in their manner-house and not having local service, they would have a small power plant in a shed. Likewise, into the 1920's much of the rural US was not served by centralized electricity and farms had generators known as "lite plants" that kept a bank of batteries charged to provide for basic electrical needs.
Of course, once the grid came to the area, the light plants and shed generators went away because they were not worth the expense or hassle.
The whole idea that distributed generation has some enviornmental benefit is bull. It doesn't matter where the power comes from, what matters is the total output and the total emissions. In this area, small and local doesn't have any advantage and may have some big disadvantages.
That's not to say distributed power doesn't have it's place. The capital cost of adding a few megawatts of capacity to an area by bringing in a few simple-cycle turbines is a lot lower than adding capacity to the back haul. The trade-off is that the operating economy is very poor.
This trade off means that the use of a few generators of a few megawatts each locally is a good choice for cold reserve. If there is an area where there are occasional times when demand is very high then such a system may be the best way to go. But that is the exception. Cold reserve generating plants are much different than baseload and account for only a small amount of the total energy output.