I just came back from the annual conference of the Heartwood Forest Council held in Southern Ohio over Memorial Day weekend. The workshops on coal, mountain top removal, and all the assorted ills that come from the "enemy of the human race" blew me away. Coal is second only to nukes as an insane energy technology. This is a powerful issue and not nearly enough emphasis is being put on it in climate change circles.

It is also an issue that splits the environmental movement between those who settle for LCCC plants as a demonstration of realpolitik, and those who do not want to jeopardize their souls with eternal damnation. Similarly it is wonderful truth serum to see which politicians are serious about climate change, and which are just bull shitting us.

It is fish or cut bait time on this issue, and it is THE issue of climate change politics.

Randy Cunningham
Cleveland, Ohio

Randy Cunningham

Have you ever heard this argument: wind power needs coal, that's why we don't think wind power is green, and that's why we don't invest in it.

The boss of Total speaking at last year's general meeting, when he was asked why his company withdrew from investing in wind.

It's an argument pushed increasingly often by the coal industry across Europe, which seems to be getting the upper-hand in many political circles: no renewables without coal.

I was just wondering if people realize that 2/3rds of the energy of a coal plant is wasted as heat, and that capturing that heat would mean you could shut down half of the coal plants, roughtly -- but of course, it would cost more to install the necessary equipment.  I don't know where the Europeans are on this -- I assume they don't consider it either.

Europeans make much more extensive use of combined heat and power than we do. But recycled energy generally can't capture all the otherwise wasted heat. I seem to remember that if you are taking a boiler primarily in place for electrical generation, and capture the waste heat on average you can increase the usable fraction by forty cent of the previous usable fraction. So if you have a 40% efficient plant generating electricity and add something to use the waste heat for district heating or an indusrial process you will end up with a 56% efficient plant. Of course the number is probably different if you start out with an industrial process and use the waste heat to generate electricity. (For one thing you don't have losses from moving the heat long distances.) Sean probably has a more up to date rules of thumb for various cases.  I'd guess they divide into these three classes:

Primary purpose electricity, secondary purpose heat, significant distance from heat end user.

Primary purpose electricity, secondary purpose heat, close to heat end user

Primary purpose heat, secondary purpose electricity, close to heat end user.

I'd also guess that ranges depend on fuel. For example, I'll bet that typical natural gas driven recycled heat systems typically are able to deliver a higher percentage of the BTU value of their fuel than coal system can.  (I'm leaving aside oil for obvious reasons.)

At any rate, I think it is worth spending the extra money to completely phase out coal rather than just using it more efficiently.

your saying (and forgive my ignorance) that CHP can't use a significant percentage of the waste heat to just deliver electricity.  Oh well, there goes that (just put CHP on all coal plants) theory.

I was saying that if you take a large coal plant whose primary purpose is to generate electricity, and use the waste heat from it for other purposes at a distance from the plant you probably will get the BTU equivalent of around 40% of the generated kWh.

The figures are different for a plant that is the same building as whatever process will use the waste heat. But I don't know exactly what those figure are, and was asking Sean who almost certainly does know.

I guess I was saying that. No the point of recycled power is that if you are already producing electricity you use waste heat for space/water heating and industrial processes. If you are already producing heat for space/water heating or industrial process you use the waste heat to produce electricity.  The only kind of plant that does the kind of recycling you are talking about are combined cycle gas turbines.

Oh one other type of recycled heat is to take waste heat from an industrial process and use it in another industrial process or for space heat, without electricity being part of it. Sorry - three posts instead of one due to afterthoughts.

Well you were asking about coal. But the reason microturbines are 80% efficient is that combined cycle turbines generating electricity only are about 60% efficient. Probably something that small does not make quite that level, but say 50%. Then use 40% of that for hot water, space heating and refrigeration,  and you get 70% average efficiency. Since that is an average, some of them probably do get "as much as" 80%. But again note that is combined BTUs, electricity, and hot water and space heatintg and refrigeration. So it is just like I said: a good rule of thumb is that you can get 40% of the energy produced as electricity in the form of useful heat for various processes. Total efficiency is higher cause gas is more efficient than coal.

But CHP is much more common in Europe than here. But all those figures 80% or whatever include heat for processes and electricity. The microturbines are producing electricity with 80% efficiency. They are producing total output of up to 80%, including electricity, heat and refrigeration. And that is the POINT of CHP or as Sean calls it recycled energy. You get high thermodynamic efficiency by producing electricity and useful heat at the same time. So I don't know what you are LOL about.

Microturbines are NOT producing electricity with 80% efficiency. They are producing electricy and space heat and refrigeration equiv to 80% (or more likely 70%) of BTUs in the natural gas

Up to a point. However remember a microturbine system is burning gas with 70% or 80% efficiency compared to a centralized system that used old 30% efficient ones. Typically about at least 20% of electricity is used for space heating and air conditioning. Replace old single cycle turbines with 58% efficient combined cycle turbines. After line losses say 55%. Use 20% of that run to ground source heat pumps with three units output for each unit of input. You end up get 88 units of heat back for each unit of gas you burn - more efficient than the micro turbines

55%
less 11% use for climate control
44% electricity other than climae control

11% (the 20% of the 55% used to run GSHP) times 3.5 (halfway between 3X & 4X multipler you get with ground source heat pumps)
=38.5

44+38.5 = 82.5% so more efficient than best microturbine.

Added advantage: when you switch to renewable electricity the GSHP pump is still usable. For that matter a portion of your capital investment in new turbines is amortized too, as you use them for backup. Of course it might be better to skip upgrading the old turbines and put the Combined cycle money directly into renewable electricity. It would be interesting to do the math on one of Seans systems where a portion of the "over-the-fence" electricity is used to run GSHP (at 3.5 units of heat or cold output for each unit of electricity input).

...According to the post I referenced, I figured that a 2KW system would run a GSHP system for a typical family, which would eliminate the need for electricity for all heating and cooling (not refrigeration, although if refrigerators were made that would integrate with a GSHP system, that would be even better).  Then you could divert the natural gas used for heating to electricity generation, and you could shut down all the coal plants in the country.

I've been musing about the possibility of decreasing the amount of natural gas needed if you had more efficient microturbines; or if it worked out better in the short run to use microturbines to again make coal plants obsolete until you have buildings that took care of all of their heating and cooling.

Then wind farms and csp would be used for "real" electric needs, not heating and cooling of various sorts, and for running high-speed rail and other electric transportation...but even then, much neighborhood and building based wind and solar could be used for much of building-based electrical needs.

I may have a few points to make but I would like to add a couple about microturbine efficiences.  One model made by Capstone Microturbine has a fuel intake (natural gas) of 240 KW.  It produces 60 KW of electric power and 120 KW of low-mid temperature hot water suitable for domestic or commercial hot water and space heating.  This is an electrical efficiency of 25% plus 50% usable thermally for a combined 75%.  The thermal output is not hot enough to drive a second thermal cycle to make electricity efficiency.  Being relatively small it may match some particular electric and thermal load profile.  If natural gas was at the old price of $2/million BTU (through year 2000), this would be the deal of the century, but today natural gas is about $12/MM BTU and jumps between $5 and over $12 depending on hurricanes and cold weather.  That is why they never took off.  However these microturines can burn almost anything including methane from a landfill and other fuels.  They have a place in many applications just like so many other solutions.

The problem is what percent is actually used. That is if you have a 25% efficient electrical generator, how much of that low temperature heat will you actually need? At minimum you will have periods of mild  weather when you need neither space heating or cooling. And because it is designed for single family homes I don't think there is an absorption chiller on the market to use the waste heat to cool your home. (If there is let me know, cause I want to publicize it.) So I doubt over the course of a year you would actually use most of that 50% in a typical home. I doubt even more that a typical highly efficient home that was well insulated and sealed would use all of it.

At 60Kw, it is for ten to thirty homes or a medium size building. OK at that size you can find an absorbition chiller. So maybe you can use most of that waste heat. But I doubt you can use all of it. Still that 75% does not match what Combined cycle with heat pumps could do.  

...first off, just to throw something else into the fray, I should have mentioned that the microturbines of the N.Y. Times article were supposed to  be used in a building of 60 units or more.  Which leads to the following hypothesis: apartment buildings are more efficient than single family homes, because you have a much smaller amount of roof per family, thus much less of the heat (or coolness) escapes.  And it would be easier, per family, to superinsulate.  Also, I think there are efficiencies for recycling and composting, but that's another matter.

Second, I think GSHP makes sense for every building.  It is almost the ultimate in resiliency -- the ideal, in my view, would be to have buildings that were minimally usable, for an extended period of time, in the case of a blackout.  With pv's on the roof and gshp below, you'd at least have heating, cooling, and hot water -- add in some other electrical generation from somewhere (solar/wind) and you have the refrigerator (and in the case of large buildings, elevators and pumping water) covered.  As I can tell you from the 2003 blackout in NYC, that combination would have been awesome.

Third, a microturbine in an apartment building -- and don't forget commercial buildings, they use as much energy as the entire residential sector -- can be used for appliances and lighting, plus some of the hot water load, particularly if you make refrigerators or even dryers use the heat pumps.

Now you're probably cutting natural gas use way down, and could cut it more with amazindrx type biogas or other sources, and you've shut down all of your coal.  Then, use the 1.7 trillion dollar wind system, or CSP, or whatever, for transportation, and badabing, a renewable energy economy is born (plus, as amazin points out, some csp for factory heat needs).

I know this all started talking about coal and ended up with microturbines but that's okay with me.  I am not aware of any microturbine manufactured below 30 KW which means all are used for larger residential (apartments, condos), and commercial and industrial that can use all of the electric and thermal output.  I forgot to mention before that absorption air conditioning is also in the range of using the higher end of the thermal energy produced.  There are several absorption cycles (types of machines) that do exist but are not commonly available these days that operate well at lower temperatures (175 to 225 deg F) and will come back for sure.  The key to microturbine success is matching the characteristics of their outputs to the required load at a site, plus the cost of the fuel.  The necessary matching loads are a balanced combination of electric, AC, and general lower temperature thermal (150 to 250 deg F; very useful for DHW and space heating and swimming pools).  And best of all is being able to use a fuel that may be lost otherwise, such as methane from a landfill or digester in an agricultural environment.  
A nice idea is a hybrid cellulosic ethanol plant/methane plant that makes the methane for a microturbine that makes electric and thermal energy needed for 100% of the energy needs to produce ethanol.  If the cellulosic source requires NO irrigation and NO fertilizer and NO natural gas at the plant, then this is a 100% solar based liquid fuel.  Also the land recovers and sequesters carbon in the massive root systems of the perennial cellulosic plants, plus all the money is spent in the US and not sent overseas.  Add a lot of mass transit, drastic efficiency increases in autos and trucks, plug-in hybrids and electric cars, and solar based liquid fuels, and where's the problem?  Later, add much lower cost fuel cells and solar produced hydrogen, and the US is reborn in green and peace.  And so is the rest of the world.   This is the future, after a few bumps.

and other "off-road" needs, like construction equipment, and make the auto fleet all-electric, then make all long-haul freight via electrified rail, and short-haul in electric trucks...thanks for the microturbine info, I think it's a good way to save on natural gas, and use natural sources of methane.

And long ago I had a debate with her about the Green party's foolish opposition to the current nuclear infrastructure. I told her the only way for Germany to eliminate it's nuclear program was to invest heavily in coal, one of the dirtiest sources of power. Her response back on the issue of nuclear waste didn't seem to want to acknowledge the issues surrounding coal. These kinds of issues can't be flipped on and off like a switch. The investment is huge, so once you go down the road, you can't turn back for decades......

Victory in Pattani