Global Warming

With corporations in the automotive industry like the Ford Motor Company bringing more attention to using corn-produced ethanol as fuel for our vehicles, the ethanol versus oil debate is going strong.

There have been numerous studies published on the subject, frequently offering conflicting reports about which fuel is better for the environment. A recent analysis of several of these studies by a University of California–Berkeley team aims to sort the chaff from the grain.

The team’s findings suggest a clear advantage to the corn-based ethanol.

“The people who are saying ethanol is bad are just plain wrong,” said Dan Kammen, co-director of the Berkeley Institute of the Environment. “But it isn’t a huge victory – you wouldn’t go out and rebuild our economy around corn-based ethanol.”

While some studies are claiming corn-based ethanol reduces our dependence on foreign oil while supporting farmers, other studies will argue it takes more petroleum to make the ethanol than it does just to use gasoline.

The team found that producing ethanol from corn does use less petroleum than producing gasoline. However, the petroleum savings were not huge but only 10 to 15 percent.

The Berkeley team analyzed six high-profile studies offering varied views of ethanol use. Many of these conflicting claims stem from using outdated data, ignoring the value of ethanol byproducts (such as corn gluten feed and corn oil), overestimating the energy needs of farm equipment, and ignoring energy needs of agricultural practices such as spreading ground limestone.

And claims that using corn-based ethanol produces less greenhouse gases and other environmental factors have not yet been concretely determined.

What would make the petroleum savings significant, according to the Berkeley team, is to produce the ethanol not from corn but from cellulose.

“Ethanol can be, if it’s made the right way with cellulosic technology, a really good fuel for the United States,” said Alex Farrell, assistant professor of energy and resources at Berkeley. “At the moment, cellulosic technology is just too expensive. If that changes – and the technology is developing rapidly – then we might see cellulosic technology enter the commercial market within five years.”

The cellulosic ethanol is made by fermenting the fibrous content of plants, and it can be made from most plant materials including farm waste – though materials such as switchgrass and willow trees work best.

Whether using corn or other plant materials, it is clear that the agricultural world has a significant impact on the environment. Another study (not associated with those reviewed by the Berkeley team) suggests that farmers can reduce greenhouse gases in ways not connected to ethanol.

Climate scientists from the Lawrence Livermore National Laboratory in California say croplands managed with certain techniques can actually lower local temperatures.

“Nearly all models used to predict climate change either ignore agriculture altogether or assume that farmers behave the same way through time,” said David Lobell, lead author of the study’s paper. “In reality, farmers are changing rapidly in response to new technologies, growth in demand, and other factors. This study suggests that these changes may have important cooling effects, especially at local scales.”

Croplands tend to reflect more sunlight than other land covers, which causes the cooling of local temperatures.

In recent decades, farmers have increased the amount of irrigation to crops and tend to plant more than one crop annually in a given field. Also, farmers tend to plow fields less than they used to, which makes the land more reflective.

These findings indicate that the connection between farming and global warming may not be as clear-cut as thought. Before, carbon levels were the main focus of trying to reduce global warming.

“This study illustrates that carbon is not the only important way that agriculture affects climate, and so focusing only on carbon may lead to an under- or over-evaluation of agriculture’s role,” Lobell concluded.