How green is a soybean?
By Adam Hinterthuer
Published September 11, 2006
Ethanol and biodiesel are growing in popularity as alternatives
to petroleum-based fuels. But the debate around these
alternatives is growing as well. Critics say it takes
more energy to produce these biofuels than what the fuels
supply in return. A new study suggests that both fuels
offer some benefits but neither of them can replace petroleum.
Jason Hill is a plant biologist and a researcher at the
University of Minnesota in St. Paul. He worked on a study
that examined the processes that turn corn into ethanol
and soybeans into biodiesel. His team measured the gas
used to run farm machinery and the energy used in biofuel
production plants and everything in between. Hill says
ethanol and biodiesel ultimately offer more energy that
what is required to produce them.
"The ethanol production process returns approximately
25 percent more energy than you put in. The biodiesel
production process returns approximately 93 percent more
energy than you put in."
Hill's study was published this summer in the Proceedings
of the National Academy of Sciences. He hopes it can point
the way to other alternatives.
"By looking at differences between them, we were
able to identify areas in the future where we can work
to both maximize our energy return and also minimize our
Hill says all the soybeans in the United States would
satisfy only half of the country's need for diesel fuel.
And all the corn in the country would satisfy only 12
percent of the nation's appetite for gasoline. Hill says
the best way to use biofuels in the near future might
be blending them into petroleum-based fuels.