A number of intrepid readers took issue with last night’s post on bioethanol. One question concerns the “energy balance” of ethanol production. Producing a gallon of ethanol requires a input of energy. If the output is greater than the input (a positive balance) then ethanol production adds to the total stock of available energy. If the reverse (a negative balance), then bioethanol production reduces the stock of energy.
Here is one answer, from “Ethanol Production: Energy, Economic, and Environmental Losses”, by David Pimentel, Tad Patzek, and Gerald Cecil (http://bilder.buecher.de/zusatz/20/20946/20946636_lese_1.pdf).
To produce a liter of 99.5% ethanol uses 43% more fossil energy than the energy produced as ethanol and costs $0.42/L($1.59/gal)… The total energy input to produce 1L ethanol is 7,333 kcal (Table 2). However, 1 L ethanol has an energy value of only 5,130 kcal. Based on a net energy loss of 2,203 kcal ethanol produced, 43% more fossil energy is expended than is produced as ethanol.
If that is correct, bioethanol production is consuming, not supplementing, available energy supplies. The authors acknowledge that there are contrary findings.
Shapouri (Shapouri et al. 2004) of the USDA is now reporting a net energy positive return of 67%, whereas in this chapter, we report a negative 43% deficit. In their earlier report, Shapouri et al. (2002) reported a net energy positive return of 34%. Why did ethanol production net return for the USDA nearly double in 2 yr, while corn yields in the U.S. declined 6% during that period (USDA 2002, 2003)? The Shapouri results need to be examined and explained.
Shapouri et al. (2004) omit several inputs. For instance, all the energy required to produce and repair farm machinery and the fermentation and distillation equipment is not included…
Shapouri et al. reported a net energy return of 67% after including the co-products, primarily dried distillers grain (DDG) used to feed cattle. These co-products are not fuel!
Who is right? Common sense sheds some light here. One of the problems with government subsidies is that they make it a lot harder to evaluate the true costs and benefits of any subsidized activity. What would happen if all government subsidies to all forms of energy production were ended immediately? Coal, oil, natural gas, and hydroelectric power would continue to be produced. The same is true, I suspect, of nuclear power.
By contrast, large scale wind and solar power generation would come to a grinding halt. Would bioethanol continue to be produced? It is pretty clear that the producers don’t think so. That is what fuels the controversy. The corn ethanol industry is tenuous enough with the government subsidies. That would not be so if the energy balance were significantly positive.
Even if the energy balance were positive, that would not mean that ethanol production is a good idea just now, let alone that subsidies are in order. Producing ethanol from corn means either diverting a substantial portion of the world’s corn crops to energy production, or significantly increasing corn production. It probably means both. The first necessarily increases the cost of corn and so raises world food prices. The second results in an increase in carbon emissions, something we are supposed to be trying to avoid.
Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products.
Okay, so what about the ideal of energy independence? I believe in that ideal like I believe in fairies, but has ethanol production reduced our consumption of foreign oil? Here is a bit by Robert Bryce at the Manhattan Institute website:
Between 1999 and 2009, U.S. ethanol production increased seven-fold, to more than 700,000 barrels per day (bbl/d). During that period, however, oil imports increased by more than 800,000 bbl/d. (In addition, U.S. oil exports—yes, exports—more than doubled, to about 2 million bbl/d.) Data from the U.S. Energy Information Administration show that oil imports closely track domestic oil consumption. Over the past decade, as oil demand grew, so did imports. When consumption fell, imports did as well. Ethanol production levels had no apparent effect on the volume of oil imports or on consumption.
I do not know whether, in the foreseeable future, biofuels might become a viable source of energy. Fossil fuels represent millions of summers followed by millions of years of underground processing. A corn crop represents one summer and all the processing is on our tab. So I am doubtful, but I do not underestimate the power of human ingenuity.
Right now bioethanol looks like a bad gamble. It doesn’t add significantly to the supply of energy, and probably subtracts from it. It doesn’t make us less dependent on foreign oil. It increases the cost of fuel and that doesn’t help the economy. It raises the cost of food, and that doesn’t help people who eat food. It’s bad for the environment. What it does do is shift wealth toward some at the expense of others. But hey, living in a corn producing state, I am all for ethanol subsidies.