Think ethanol is the answer to all of our concerns over sources of renewable fuel? Prof. David Pimentel Ph.D ’51, ecology and evolutionary biology, might urge you to think again. According to a study he co-wrote, producing ethanol from crops like corn actually requires more energy than it yields.
“To get energy from corn, you’ve got to raise the corn, which takes several different inputs,” Pimentel said.
He pointed out that the production of farming machinery, diesel fuel, gasoline, nitrogen fertilizer, lime and hybrid corn seeds all require fossil fuels.
Furthermore, after the corn is produced, the corn must go through a fermentation and distillation process in order to produce ethanol that can be used as fuel, which Pimentel says is also very energy-intensive.
Pimentel co-wrote his study with Prof. Tad Patzek, petroleum engineering, University of California-Berkeley. It was published in the March 2005 issue of Natural Resources Research, and says, among other things, that ethanol production using corn grain requires an input of 29 percent more energy from fossil fuels than it produces. They estimated the amount of fossil fuels consumed by the resources required to grow corn, including production and use of machinery, herbicides, insecticides, electricity and irrigation. The study also attempts to estimate the amount of fossil fuel energy required for the process that ferments and distills the corn to produce ethanol.
Ethanol is currently being considered as a prospective alternative fuel source, and many proponents claim that it can help reduce our dependence on fossil fuels. In January 2006, President George W. Bush said in his State of the Union address that the government will fund research focusing on ethanol production and that he wants to make ethanol a practical and competitive alternative fuel source within the next six years.
When asked if President Bush’s plan was feasible, Pimentel said, “It’s not going to happen. … This whole thing is going to collapse in the not too distant future.”
Furthermore, Pimentel asserts that corn production can be damaging to our environment. He says that the production of corn is highly taxing on farmland, and this, he claims, means that ethanol produced from corn is not actually a renewable resource.
“Corn is a major cause of soil erosion in the United States,” he said. “Corn uses more nitrogen fertilizer than any other single crop in the nation, and 25 percent of that nitrogen is getting into our rivers and streams. That’s a serious problem. Corn uses more insecticides than any other crop in the nation, and that gets into streams and lakes. Corn uses more herbicides than any other crop in the nation.”
There are some experts who disagree with Pimentel’s analysis of the viability of ethanol as an alternative fuel.
Prof. Larry Walker, biological and environmental engineering, calls Pimentel’s data and analysis “flawed.”
“Our energy future is a bit more uncertain these days, and I strongly believe that we need to continue to build the portfolio of energy technology that we can bring to bear on the future,” Walker said. “The goal of research and development is to improve on important technologies – to make them more efficient and environmentally friendly.”
Walker believes that research and development will further improve the potential of ethanol to serve as a viable fuel source.
“There has been tremendous progress made in our ability to produce and to convert plant-based resources for energy and industrial chemicals,” he said. “Yes, there are challenging issues, such as effective management of soil erosion and the safe use of pesticides, which we must address as we begin to build a biofuel industry.”
Pimentel maintains that the future feasibility of ethanol as an alternative fuel source is highly questionable and that its primary proponents are large companies with profit motives.
“It’s politics and big money that’s driving this,” he said, citing government subsidies that are in place in order to make ethanol more competitive in the marketplace.
Some of the research that Pimentel and Patzek criticize in their study is that of Hosein Shapouri, an agricultural economist at the U.S. Department of Agriculture, who estimated that ethanol yields more energy than is required to produce it – the opposite of what Pimentel and Patzek contend.
“They omit a lot of the inputs [required to produce ethanol],” Pimentel said. “They omit all the energy for the processing equipment, and the irrigation. … Then you could look at how they allocate energy of natural gas for the production of nitrogen fertilizer, and they’re about a third below what we include.”
Shapouri argues that some of the energy inputs that Pimentel and Patzek estimate are very difficult to accurately calculate.
“It is true that I exclude some energy inputs such as energy used by labor, energy used in farm machinery and energy used in cement, stainless steel and structural steel. There is no way to estimate these variables,” Shapouri said.
Shapouri further contends that the estimates that Pimentel provides for the inputs required to produce ethanol are too high.
One study published this year in the journal Environmental Science & Technology compares six different studies examining the net energy yielded from ethanol production, and points out that Pimentel and Patzek’s study is the only one of the six that calculates a negative energy return. The study further states that the energy return on investment for gasoline is below the return on investment calculated by Pimentel and Patzek for ethanol, and therefore, the study argues, ethanol still requires less fossil fuels to produce than gasoline.
Pimentel asserts that these other studies examining the energy return of ethanol have excluded important factors that should be taken into account when calculating how much energy from fossil fuels is required to produce ethanol. He remains highly critical of ethanol’s viability as an alternative fuel source.
“I think it is a scam,” he said. “It’s misleading the nation and taking us on a path that we shouldn’t be following for environmental and economic reasons.”
Pimentel instead encourages scientists and the government to focus on other sources of energy.
“I’d like to see more research into other renewables, including [solar energy] and wind,” he said.
Pimentel also claims that more research and investment in coal would allow us to burn it more cleanly and efficiently and suggests that we focus on clean coal technologies in the immediate future, instead of investing in ethanol.
Archived article by Andrew Beckwith
Sun Senior Writer