Better To Burn Than To Brew Ethanol
Coming on the heals of the EPA and CARB decisions, to include all production emissions when evaluating biofuels, a new study from the Carnegie Institution's Department of Global Ecology says that it may be better to burn crops than turn them into biofuels. The UN has reported that world food prices are rising due to competition with government subsidized biofuel programs. Combined with new concerns over nitrous oxide production from agricultural crops, this may signal the death of America's foolish foray into crop based ethanol.
Writing in the online edition of Science, researchers report that the best use of biomass is to convert it to electricity, rather than ethanol. They calculate that, compared with ethanol used for internal combustion engines, bioelectricity used for battery-powered vehicles delivers more miles of transportation per acre of crops. As we previously reported, the amount of nitrous oxide released by farming biofuel crops such as corn or rape offsets any advantage offered by reduced emissions of CO2. Directly burning biomass to make heat for electrical generation provides double the greenhouse gas offsets compared with turning it into ethanol.
The catch, of course, is having electric vehicles (such as plugin hybrids) to use the electricity. According to the paper's abstract:
Biomass could power either internal combustion or electric vehicles, but the relative land-use efficiency of these two energy pathways is not well quantified. Here, we show that bioelectricity outperforms ethanol across a range of feedstocks, conversion technologies, and vehicle classes. Bioelectricity produces an average 81% more transportation kilometers and 108% more emissions offsets per unit area cropland than cellulosic ethanol. These results suggest that alternative bioenergy pathways have large differences in how efficiently they use the available land to achieve transportation and climate goals.
The numbers cannot be denied. “It's a relatively obvious question once you ask it, but nobody had really asked it before,” says Dr. Chris Field, director of the Department of Global Ecology at the Carnegie Institution and the study's co-author. “The kinds of motivations that have driven people to think about developing ethanol as a vehicle fuel have been somewhat different from those that have been motivating people to think about battery electric vehicles, but the overlap is in the area of maximizing efficiency and minimizing adverse impacts on climate.”
Field, who is also a professor of biology at Stanford University and a senior fellow at Stanford's Woods Institute for the Environment, is part of a research team that includes lead author Elliott Campbell of the University of California, and David Lobell of Stanford's Program on Food Security and the Environment. Using publicly available data on vehicle efficiencies from the US Environmental Protection Agency and other organizations, the researchers analyzed total life-cycle energy and emissions costs for both bioelectricity and ethanol technologies. The life-cycle analysis took into account not only the energy produced by each technology, but also the energy consumed in producing the vehicles and fuels.
There are other applications that need electrical power and the idea of burning biomass, wood in particular, has been catching on in Europe and the US. A number of wood-burning power plants have been built or are being proposed in New England, encouraged by government incentives and environmentalists who are pushing wood and other sources of biomass as a renewable, eco-friendly substitute for fossil fuels. Not long ago, the Economist reported that Public Service of New Hampshire, the state’s largest electric utility, successfully tested a novel fuel mixture for one of its electricity-generating boilers: coal mixed with cocoa-bean shells.
The test used 36,000 pounds (16,400kg) of bean shells, which came from Europe by way of Lindt USA. A subsidiary of Lindt & Sprüngli of Switzerland, Lindt USA operates a plant in nearby Stratham. The shells, which have a thermal value similar to that of wood, were mixed with coal in a 1-to-33 ratio and reportedly burned nicely. From coco bean shells to forest thinings, burning biomass for co-generation (producing both electricity and heat) is taking off. But like wind farms and massive solar arrays, wood-burning plants can spark fierce local opposition.
On a more personal scale, some people are even using corn burning furnaces to heat their homes. I have an Aunt and Uncle who heat their Pennsylvanian farm house with corn. They report that the house stays cozy and the corn furnace burns cleaner than oil. Two reasons corn is so attractive as a heat source are that dry shelled corn is easily handled and supplies are plentiful in farm country. Shelled corn also has a high heat energy per unit weight. Here's how shelled corn measures up to other solid fuels.
Shelled Corn 7000 BTU/lb (16,200 kJ/kg) at 15% Moisture Content Straw 6550 BTU/lb (15,200 kJ/kg) Air Dried Corn Stover 7540 BTU/lb (17,500 kJ/kg) Air Dried Wood 8000 BTU/lb (18,500 kJ/kg) Air Dried
As can be see from this table, shelled corn has heat energy close to that of wood. Unfortunately, the price of corn has been rising due to demand from the heavily subsidized corn based ethanol industry, and there lies the rub—the biggest impediments to using biomass effectively are government funded renewable energy programs.
The analysis is clear: while cellulose is less harmful than corn, burning either to make electricity is better than turning them into biofuel. So why are the Obama Administration and members of the US Congress still strongly backing subsidies for corn based ethanol? Politics, pure and simple. They claim to be green but it is concern over votes that matter, votes and the heeding the voices of lobbyists like Democrat insider Wesley Clark. So the politicians continue to pander and the lobbyists lie, but the science is becoming clearer and clearer: when it comes to corn, it is better to burn than to brew ethanol.
Be safe, enjoy the interglacial and stay skeptical.