Biodiesel is has an even better net energy ratio than we thought. Older studies said biodiesel had a 3.2 to 1 energy ratio, but a comprehensive study by the NREL and USDA have shown a positive net energy ratio of 3.5 to 1. This is big news and puts to bed the idea that it takes nearly as much energy to make biofuels as we get out of the biofuels. Corn ethanol? Yeah, not particularly efficient (1.3 to 1). Biodiesel? 3.5 to 1.
This means that for every one unit of energy (say, gallon of fuel) it takes to make biodiesel, we get 3.5 gallons of biodiesel. Where does the extra energy come from? That's easy: the sun. Plants take the sun's power and convert it to energy better than the best solar panels do.
Here's the National Biodiesel Board's press release.
Feb. 6, 2008
Biodiesel Yields Even Higher Energy Balance
New Study Shows 3.5 Units of Energy Gained For Every Unit Needed to Produce Biodiesel
ORLANDO, Fla.–
A new analysis shows that the energy balance of biodiesel is a positive
ratio of 3.5-to-1. For every unit of fossil energy needed to produce
the fuel over its life cycle, the return is 3.5 units of energy,
according to new research conducted at the University of Idaho in
cooperation with the U.S. Department of Agriculture (USDA). The
announcement of the increase—up from 3.2—was made today at the National
Biodiesel Conference & Expo in Orlando.
The Department of Energy National Renewable Energy Lab (NREL) and USDA
had produced the first comprehensive life cycle inventory for biodiesel
in 1998. That landmark research found a 3.2 energy balance for
biodiesel, while petroleum diesel yielded only 0.83 units of energy per
unit of fossil energy consumed. The many changes that have occurred in
the U.S. biodiesel and agricultural industries since the 1990s prompted
researchers at the University of Idaho to update the study in
cooperation with the USDA. Both the 1998 and 2007 study are based on
biodiesel production from soybeans, which according to U.S. Census data
is responsible for more than 80 percent of 2007 estimated biodiesel
production. Biodiesel’s energy balance improved in the 2007 study even
though the new analysis is more comprehensive than previous work, and
even extends to the energy required to manufacture the farm machinery
used to produce soybeans.
“The bottom line is that the energy balance of biodiesel has definitely
improved in the last decade,” says University of Idaho Department Head
of Biological and Agricultural Engineering Jon Van Gerpen, who credits
Assistant Professor Dev Shrestha and graduate student Anup Pradhan for
their work on the study. “The increase in soybean yields and a decrease
in herbicide use greatly contributed to the increased energy balance.
Meanwhile, energy used for crushing soybeans is significantly lower
than what was reported in the NREL study.”
The researchers found national soybean yield data from 1975 to 2006
shows that the yield has increased at the rate of 0.6 bushels per acre
per year. Yet, the fertilizer application rate has essentially remained
the same and the herbicide application rate has declined to one-fifth
of its rate in 2000. Reduced herbicide applications have the added
benefit of requiring less diesel for field spraying.
At the processing level, technology improvements at soybean crushing
facilities led to 55 percent less energy needed than what was reported
in the NREL study. Although transesterification to convert soybean oil
into biodiesel has also become more energy efficient, this process only
contributes a small fraction of overall energy in the lifecycle
analysis.
Today’s announcement came during a conference session highlighting
promising feedstock developments, ranging from higher oil content in
soybeans to new feedstocks, like algae. The NBB has launched a
feedstock development initiative to help the market spur additional
sources for biodiesel.
“As demand for biodiesel climbs, having enough feedstock available at a
competitive price will continue to be an important issue,” said Ed
Hegland, NBB chairman and a Minnesota soybean grower. “Soybean oil will
continue to play an important role, but we are also excited about the
prospect of algae and other feedstocks on the horizon. A rising tide
lifts all boats.”
Biodiesel is a cleaner burning alternative fuel that can be used in any
diesel engine. A domestically produced, renewable fuel, it can be made
from animal fats or vegetable oil. The use of biodiesel in a
conventional diesel engine results in a substantial reduction of
unburned hydrocarbons, carbon monoxide, and particulate matter.
