Coal Won’t Be Easy To Replace
I just had a very interesting call with a private equity company that I thought I’d share, as it illustrates what we’re up against when it comes to energy.
When I asked about the firm’s energy practice, he said, “We trade coal; we set up deals between mines and utilities around the world.”
“All right,” I replied. “Any interest in going beyond that, perhaps into biomass? I would think that there are pressures on the coal industry that will eventually have an effect.”
“You mean shale gas?” he asked. “The low cost of gas is making this tough, for sure.”
“I was thinking more along the lines of sustainability and the environment – that kind of thing. I don’t want to sound preachy, but coal’s not good for the health of the planet.”
“Oh, that’s an extremely minor factor; that won’t put a dent in coal. Now, the Europeans have a slight interest in biomass, especially wood pellets. But in the U.S., there is almost zero interest. You really can’t touch trees whether they’re living or dead, and you can’t take waste wood across state lines. There’s a list of regulations against biomass here are as long as your arm. If you can prove that you’re using pure saw dust that came exclusively as a result of the manufacturing of lumber, that’s fine. Everything else is a hassle beyond your wildest dreams.”
Wow, you have to hand it to those coal guys; they’ve done a really impressive job in cementing in their position in the U.S. energy world, and it really will take some work to get them out of here.
I’m rolling up my sleeves.
Craig,
I’m actually fond of pyrolized biomass co-firing in supercritical and ultra-supercritical coal plants. That’s one area in which the use of biomass has a very strong return on investment, and we can see much better return in terms of carbon abatement than we might see in something like ethanol…
But it’s not just the regulatory framework that will prevent this from greatly impacting coal. We have to be realistic.
The energy content of a ton of wood pellets is ~5 MWh/T… If you co-fired that in a supercritical coal plant (~40% efficient), you’d get ~2 MWh. But if it was a pure biomass facility you would only get ~25% efficiency (~1.25 MWh) – because the lower energy density fuel means you have a sub-critical burner.
So in order to satisfy the current contribution of coal you’d need to provide ~1.4 billion tons of wood pellets/year. About 27 tons of wood pellets can be harvested per acre per year, so to replace coal entirely with biomass demand is about 51.8 million acres. That’s harvesting (clear-cutting) a land area equal to ~1/9th the total amount of cropland in the U.S. Since it takes about 25 years to grow back, you’ll need ~1.3 billion acres of forest in order to make this a completely renewable project.
That’s 57% of the land area in America.
I like biomass co-firing because it’s cost effective and efficient… but this will not ever make a considerable dent in our coal consumption because there’s just not that much bio-energy growing in the U.S. This might be good for as much as ~5% of coal’s current yield, but it’s probably better to just focus on as a waste consumption offering rather than a major power producing renewable alternative.
I’m sorry if this feels overly critical or dismissive… but based on the title, this was the blog post I was expecting to read.. so I thought I’d write it.
😉
Glenn
This is very interesting. I am wondering what your thoughts are concerning the torrefaction of biomass to co-fire in coal plants. I’m not sure I understand how torrefaction works but I gather that it concentrates biomass so it is easier and cheaper to transport. Perhaps this would be a better use of biomass than trying to convert it into biofuels.
I wish you and your Dad all the success in the world with your Windfuels venture.
Tim,
Torrefaction and pyrolysis are essentially the same process. Torrefaction was the industry word, but that effectively is just partially pyrolysing the biomass.
That is what I was referring to. The result is essentially the removal of ~100% of the water from the wood, increasing its energy density to the maximum possible. It results in a reduction of ~10% of the potential energy, and gets rid of ~80% of the weight, or >30% of bone-dry weight (bone-dry biomass still contains water).
If you don’t do that before co-firing, then you reduce the efficiency of the coal combustion, and you greatly increase the energy density of the fuel you have to truck around.
The 27 tons of biomass/acre that I had assumed above was pre-torrefaction, not post… and I forgot to reduce the usable biomass energy density by 90% accordingly. Oops.
🙂
Thanks for the well wishes on WindFuels… we should have fuels by the end of the year.
Taking the upper HHV (cal value) of wood chips as 15MJ/Kg, 27t/acre of wood chips equates to about 28KWh/sq-m. This represents a solar energy capture of about 1/4 of one percent. Put this through a biomass power statiion at 25% efficiency results in about 0.1% of the Sun’s energy being converted to electricity.
By comparison, CPV (Concentrating PV) achieves over 30% conversion efficiency (over 40% for the cell only) or in other words is over 300 times more efficient at producing electricity from the sun than biomass, or even higher if CPV is located in hot sunny deserts. Put another way an acre (ha) of biomass crops could be replaced by about 12 sq-yds (25 sqm) of solar panels in a place where nothing much can be grown.
My view is that Biomass for fuel production should be focused on areas where (currently or in the near future) there is no other suiatble substitue to chemical fuels, e.g. air travel and shipping.
Nick,
In terms of actual help for the environment, it would be better to pyrolyze the wood into charcoal then till it into the soil, then grow more trees and repeat the process… We don’t do that, because there’s no economic gain from growing/harvesting/grinding/pyrolyzing/and tilling a bunch of forestland.
Economics plays a role. If we can get the wood mass co-fired at ~$200/ton, and recover 2 MWh/ton, then that is only $100/MWh for low-carbon electricity. It is flat-out-impossible to get that same price for low-carbon electricity from solar panels, even in the desert. In any region which grows heavy woodlands, the solar panel’s capacity factor will be far lower, and the cost of energy from those panels will be far higher.
Wind turbines should be built in windy areas, and solar panels should be put up in the desert… but the forestland would not benefit well from either option.
One possibility just coming into the commercial arena is to use solar heat to displace some of the coal currently used to generate “bypass steam”. Bypass steam is used to heat the water which will be turned into steam up to around 200C in liquid form under pressure. This process us used to prevent knocking – which would happen if the water began to turn into steam prematurely. Such knocking causes cavitation which can seriously damage the pre-heat system.
By using solar heat in this way using parabolic trough solar thermal collectors in high DNI areas, the solar heat to electricity conversion takes on an effective efficiency close to that of the supercritical coal fired plant. (Much higher efficiency than a solar thermal plant standing alone, and without many of the hardware costs of building a steam plant, turbines, transformers etc. all of which are already existing
I believe that in the right location, this system can add around 20% to steam generating capacity at a coal fired plant just when it is most needed for air conditioning, and likewise reduce carbon intensity by a similar proportion. (Obviously varying with sunshine intensity through the day, and with weather variations)
I realise this is not an ideal solution, but it does offer a step in the right direction.
Gary,
It’s a good step in the right direction.
My response to the original post was that it’s a long way to go…
We need to take advantage of every step we can take.
“Wow, you have to hand it to those coal guys; they’ve done a really impressive job in cementing in their position in the U.S. energy world, and it really will take some work to get them out of here.”
Especially when stuff like this is going on.
http://www.dylanratigan.com/2012/06/06/it-aint-easy-going-green/
Wow, that’s really sickening. Please see this: http://2greenenergy.com/oil-and-coal-companies/23965/