Ethanol Energy Efficiency

Biofuels are considered by many as an environmentally friendly replacement for fossil fuels, although there are also many who question their green credentials due to several factors, such as competition for land with food crops and what is known as net energy. So let's have a look at the issue of ethanol energy efficiency.

In order to do that we have to ask two main questions: how much energy is necessary to grow and process the prime matter of ethanol and how much energy is contained in the final product, ethanol itself. In order to measure the level of ethanol energy efficiency, several studies have been carried out and reached different conclusions.

Some of them claim that ethanol is energy positive, with an estimated figure of around 35%. That is the ethanol energy efficiency claimed by a study carried out by the U.S. Department of Energy�s Argonne National Laboratory conducted by Michael Wang. The research was conducted by USDA, Michigan State University, the Colorado School of Mines, the Institute for Local Self-Reliance and other public and private entities. Other studies arrived at a similar figure.

However, two other studies paint a different picture. A Cornell University and University of California-Berkeley 2005 study concluded after detailed analysis of the whole cycle of ethanol production that corn, switch grass and wood biomass require 29, 45 and 57 percent more fossil energy than the fuel produced, respectively.

That same year, a study published in the July 2005 issue of BioScience, the journal of the American Institute of Biological Sciences (AIBS), concluded that even though sugar cane ethanol net energy efficiency was 3.7 times higher than the energy required to produce it, reducing deforestation was more effective to decarbonize the environment. The study added that, in America, ethanol would not do much to reduce dependence on foreign fossil fuel, and the environmental impact of corn agriculture outweighed the benefits. They suggested the pursuit of multiple alternatives and recommended ethanol for regions with critical pollution problems. With so much contradicting data related to ethanol energy efficiency, possibly the best conclusion we can reach at this point is that ethanol is not inherently net energy positive, negative, environmentally friendly or unfriendly as an alternative to fossil fuel. It will depend on the context and type of raw material in question. No single energy source is likely to be the panacea to the big energy challenge we have in our hands.