May 08, 2009
Corn Better For Electricity Than For Ethanol
Corn as a form of biomass energy would reduce carbon dioxide emissions and move cars more miles if used to generate electricity to power electric cars.
Scientists are examining biomass - plant matter that's grown and used to generate energy - as a potential power source. Two biomass technologies involve ethanol and electricity. Biomass converted into ethanol, a corn-based fuel, can power internal combustion vehicles. Biomass converted into electricity can fuel a vehicle powered by an electric battery.
A study by University of California, Merced, Assistant Professor Elliott Campbell and two other researchers in the online edition of this week's Science journal suggests that biomass used to generate electricity could be the more efficient solution.
In the study, Campbell, along with Christopher Field, director of the department of global energy at the Carnegie Institution and David Lobell of Stanford University, the scientists found that biomass converted into electricity produced 81 percent more transportation miles and 108 percent more emissions offsets compared to ethanol.
In other words, said Campbell, vehicles powered by biomass converted into electricity "got further down the road" compared to ethanol. As a result, Campbell continued, "we found that converting biomass to electricity rather than ethanol makes the most sense for two policy-relevant issues, transportation and climate."
I find this an unsurprising result. Previously I've argued that it makes more sense to burn corn kernels in place of heating oil as a heat source rather than use corn to produce ethanol. Why? Almost all the heat from burning the full kernel goes to producing space heat. Burning corn to produce heat for electric power generation will be highly efficient in a big electric power plant. By contrast lots of energy gets used to use part of corn to make ethanol.
My guess is that using corn to replace heating oil will be more efficient than using it to generate electricity to power electric cars. Better to displace the heating oil from heating and then use that heating oil as diesel fuel to power cars. Only once that displacement has been done does it make sense to begin to consider corn for electric power generation.
But keep in mind that the Merced researchers were comparing energy usages of corn. One still needs to compare the use of corn to generate electricity (or heat) with the use of wood or nuclear power or other energy sources. But this Merced comparison amounts to trying to find a more efficient way to placate the corn lobby with a different way to increase corn demand.
I expect you all see there's an obvious problem though in using corn to generate electricity specifically for transportation: the need for battery powered cars. But if the goal is to reduce carbon dioxide emissions then corn would be best used to displace coal for electric power generation. That displacement would not require production of millions of still rather expensive and limited range electric cars.
Misses the point entirely. There's no reason at all to burn corn in standing generators, because we have plenty of available, cheap fuel to do just that. We make ethanol out of corn so we can pump it into our gas tanks. We can't do that with the kind of fuel we burn in our power plants.
Whenever somebody comes up with an idea for using more corn, I start to twitch:
"When a Crop Becomes King" by Michael Pollan, in the NYTimes on July 19, 2002:
* * *
Like the tulip, the apple and the potato, zea mays (the botanical name for both sweet and feed corn) has evolved with humans over the past 10,000 years or so in the great dance of species we call domestication. The plant gratifies human needs, in exchange for which humans expand the plant's habitat, moving its genes all over the world and remaking the land (clearing trees, plowing the ground, protecting it from its enemies) so it might thrive.
Corn, by making itself tasty and nutritious, got itself noticed by Christopher Columbus, who helped expand its range from the New World to Europe and beyond. Today corn is the world's most widely planted cereal crop. But nowhere have humans done quite as much to advance the interests of this plant as in North America, where zea mays has insinuated itself into our landscape, our food system — and our federal budget.
So it seems corn has indeed become king. We have given it more of our land than any other plant, an area more than twice the size of New York State. To keep it well fed and safe from predators we douse it with chemicals that poison our water and deepen our dependence on foreign oil. And then in order to dispose of all the corn this cracked system has produced, we eat it as fast as we can in as many ways as we can — turning the fat of the land into, well, fat. One has to wonder whether corn hasn't at last succeeded in domesticating us.
The problem with any kind of biomass energy is that it diverts farmland from food production. With the planet's population expected to expand from 6.5 B to around 8 B in the next 20 years, this seems fool-hardy. The brief spike in corn prices last year before the ethanol bubble collapsed led to food riots in many poor countries.
A biomass-based energy system would require the cutting down and planting of almost all our remaining forest, including the Amazonian and Congo rain forests. If species diversity depends on the existing rainforests, then biomass energy will devastate diversity.
Our current energy debate is controlled by the Lysenkoists. We need some real science and engineering. The various problems people identify, including global warming, should be driving us to a very large expansion of nuclear power. If we did the French thing, our base electricity generation capacity would be 80% nuclear rather than the 20% we now have. An 80% nuclear generation system would require the construction of around 500 new plants, of which 100 would replace the elderly plants we have today, many of which are 40 years old.
These scientists are making the point that corn ethanol is a bad idea. I doubt that corn electricity makes sense either. But it makes more sense than corn ethanol. If we are going to do something dumb let us choose a least dumb option.
Unfortunately the politics favors a more dumb option.
We ought to encourage Third World population control. 2 or 3 billion more poor hungry humans is a bad idea.
Nuclear power: Yes, a much better idea than corn ethanol.
One potential benefit of biomass electricity: If carbon dioxide starts causing so much global warming that it becomes a big problem then we could burn biomass to generate electricity, capture the CO2, and sequester the CO2. That would pull CO2 out of the atmosphere. But that's not a policy for today.
Actually, no one has done the analysis of corn ethanol production including the use of distillers grains as fodder. At least I haven't run across the analysis.
Iowa is now a larger beef producer than Texas.
The only mentions in those links were, respectively:
And E3 Biofuels LLC is finding ways to get more out of all parts of the corn, by building plants near dairy farms and feeding cows the byproducts of ethanol processing, then using energy from the animal waste to help power the plants. "Wastes are converted to valuable products, such as biogas and biofertilizers, which replace fossil fuels and their derivatives," David Hallberg, president and chief executive of Omaha-based E3, wrote me in an email.
The close evaluation
required to replicate the net energy results showed
that these two studies also stand apart from the
others by incorrectly assuming that ethanol
coproducts (materials inevitably generated when
ethanol is made, such as dried distiller grains with
solubles, corn gluten feed, and corn oil) should
not be credited with any of the input energy and
by including some input data that are old and
unrepresentative of current processes, or so
poorly documented that their quality cannot be
evaluated (tables S2 and S3).
James Bowrey: I think you need to look at some of the things those pages reference.
E3 Biofuels filed for bankruptcy a year and a half ago, while oil prices were still on their way up. This should tell you something.
There are limits to how much DDG can be fed to livestock. One account I found mentioned that a livestock operator found that calves were dying of sulfur toxicity when the DDG fraction was ~50%. This cuts into profits, not to mention being an animal-welfare issue.
If we are going to try to support the price of corn with biofuels, the thing to do is to encourage conservation plantings to be done in perennial species like hybrid Miscanthus giganteus and remove acres from corn production. The biomass productivity is higher (maize is ~4 tons/ac/yr, Miscanthus has exceeded 20 tons/ac/yr), the inputs are much lower, and erosion is close to zero. The major advance required is to convert to a much more compact form for transport; fast pyrolysis to bio-oil in the field addresses that.
I'm sure I've noted before that electricity is a far more efficient way of turning biomass into mileage than ethanol, but I can't find any direct evidence on my own blog; I probably made it in comments elsewhere. I guess I should be more consistent in turning these things into posts.
One account I found mentioned that a livestock operator found that calves were dying of sulfur toxicity when the DDG fraction was ~50%.
Well since the recommended percentage of DDG is around 20% for cows and less for calves...
That does rather cut the amount of ethanol that can be made from corn. That is, unless you want to burn or otherwise dispose of the excess DDG, which makes claims about "coproduct credits" for EROI and GHG reduction more than slightly hypocritical.