A: Most studies show the production of ethanol fuels from the
1990's and onward to have a positive energy balance, meaning more energy
comes from using the ethanol as a vehicle fuel than making it. My
coauthored book published in 1985, The Forbidden Fuel (Bernton, Kovarik,
and Sklar), covers this issue and my recent article in Ethanol Producer
Magazine in June 2005 elaborates on how to practically produce ethanol
fuels entirely on renewable energy.
The Environmental Protection Agency announced in March 2006, that it has
proposed a rule that would raise the emissions threshold for corn milling
plants that produce ethanol fuel, allowing those plants to emit up to 250
tons per year of air pollutants before triggering tougher restrictions on
production. Currently, corn-milling plants can emit 100 tons of pollutants
per year. This was an attempt, sadly, to allow ethanol production
facilities to use dirtier fuels, which is highly unnecessary.
Many issues impact energy balance including the use of petroleum
fertilizers in growing the resource or utilization of other forms of
nutrients such as manures and composted organic materials, whether waste
biomass 'behind the fence' of the ethanol plant is used for drying the
biomass (a very heavy energy user) and for fermentation heat. Older
studies highlighted Brazil where the sugar industry was very energy
intensive and used lots of old diesels - so energy intensity was poor. The
newer sugar and ethanol plants are much more efficient.
There have been numerous studies on ethanol fuels energy balance and the
strongest are by Shapouri and Duffield of USDA's Office of Energy Policy
and New Uses, and Wang from the Center for Transportation Research, Energy
Systems Division, Argonne National Laboratory. Their July 2002 studies
estimated the Net Energy Value (NEV) of corn ethanol. However, variations
in data and assumptions used among the studies have resulted in a wide
range of estimates. This study identifies the factors causing this wide
variation and develops a more consistent estimate. They conclude that the
NEV of corn ethanol has been rising over time due to technological
advances in ethanol conversion and increased efficiency in farm production
- and the research shows that corn ethanol is energy efficient as
indicated by an energy output / input ratio of 1.34. Quoting from their
Agricultural Economic Report No. 813: "Corn ethanol is energy
efficient...for every BTU dedicated to producing ethanol there is a 34%
energy gain... Only about 17% of the energy used to produce ethanol comes
from liquid fuels, such as gasoline and diesel fuel. For every 1 BTU of
liquid fuel used to produce ethanol, there is a 6.34 BTU gain." Full
report (PDF file, 176 kb): www.usda.gov/oce/reports/energy/aer-814.pdf
In "How Much Energy Does It Take to Make a Gallon of Ethanol?", David
Lorenz and David Morris of the Institute for Local-Self Reliance (ILSR)
state: "Using the best farming and production methods, the amount of
energy contained in a gallon of ethanol is more than twice the energy used
to grow the corn and convert it to ethanol." A 1992 ILSR study, based on
actual energy consumption data from farmers and ethanol plant operators,
found that the production of ethanol from corn is a positive net energy
generator. In this updated paper the numbers look even more attractive:
more energy is contained in the ethanol and the other by-products of corn
processing than is used to grow the corn and convert it into ethanol and
by-products (see report at second link). In contrast, Cornell professor
David Pimental has been on a long time crusade to prove otherwise, and is
about the only one I can find who claims the energy balance is negative.
But on another note, the issue is a somewhat esoteric one. If we are using
domestic coal to provide energy to produce liquid fuels, or even better,
domestic renewable energy -- even if ethanol had a negative energy balance
- wouldn't the benefits still be extremely positive? The US would import
less petroleum from non-democratic countries, our trade deficit would be
lower, and our tail pipe emissions would be less in most emissions
categories.
The use of ethanol and now biodiesel are critically important renewable
energy options for our country. The energy balance is positive, and we
must insure that their production meets traditional emissions standards,
so consumers get the optimum energy/environmental resource.
Scott Sklar