Switchgrass grown for biofuel production produced 540 percent more energy than needed to grow, harvest and process it into cellulosic ethanol, according to estimates from a large on-farm study by researchers at the University of Nebraska-Lincoln (UNL).
Results from the five-year study involving fields on farms in three states highlights the prairie grass' potential as a biomass fuel source that yields significantly more energy than is consumed in production and conversion into cellulosic ethanol, said Ken Vogel, a U.S. Department of Agriculture-Agricultural Research Service geneticist in UNL's agronomy and horticulture department.
The study involved switchgrass fields on farms in Nebraska, North Dakota and South Dakota. It is the largest study to date examining the net energy output, greenhouse gas emissions, biomass yields, agricultural inputs and estimated cellulosic ethanol production from switchgrass grown and managed for biomass fuel.
"This clearly demonstrates that switchgrass is not only energy efficient, but can be used in a renewable biofuel economy to reduce reliance of fossil fuels, reduce greenhouse gas emissions and enhance rural economies," Vogel said.
The joint USDA-ARS and Institute of Agriculture and Natural Resources study also found greenhouse gas emissions from cellulosic ethanol made from switchgrass were 94 percent lower than estimated greenhouse gas emissions from gasoline production.
In a biorefinery, switchgrass biomass can be broken down into sugars including glucose and xylose that can be fermented into ethanol similar to corn. Grain from corn and other annual cereal grains, such as sorghum, are now primary sources for U.S. ethanol production.
In the future, perennial crops, such as switchgrass, as well as crop residues and forestry biomass could be developed as major cellulosic ethanol sources that could potentially displace 30 percent of current U.S. petroleum consumption, Vogel said. Technology to convert biomass into cellulosic ethanol is being developed and is now at the development stage where small commercial scale biorefineries are beginning to be built with scale-up support from the U.S. Department of Energy.
This study involved 10 fields of 15- to 20-acres each. Trials began in 2000 and 2001 and continued for five years. Farmers were paid for their work under contract with UNL and documented all production operations, agricultural inputs and biomass yields. The researchers used this information to determine the net energy estimates.
Switchgrass grown in this study yielded 93 percent more biomass per acre and an estimated 93 percent more net energy yield than previously estimated in a study done elsewhere of planted prairies in Minnesota that received low agricultural inputs, Vogel said. The study demonstrates that biomass energy from perennial bioenergy crops such as switchgrass can produce significantly more energy per acre than low input systems. Less land will be needed for energy crops if higher yields can be obtained.
Researchers point out in their study that plant biomass remaining after ethanol production could be used to provide the energy needed for the distilling process and other power requirements of the biorefinery. This results in a high net energy value for ethanol produced from switchgrass biomass. In contrast, corn grain ethanol biorefineries need to use natural gas or other sources of energy for the conversion process.
In this study, switchgrass managed as a bioenergy crop produced estimated ethanol yields per acre similar to those from corn grown in the same states and years based on statewide average grain yields.
"However, caution should be used in making direct ethanol yield comparisons with cellulosic sources and corn grains because corn grain conversion technology is mature, whereas cellulosic conversion efficiency technology is based on an estimated value," Vogel said.
Vogel said that he does not expect switchgrass to replace corn or other crops on Class 1 farm land. He and his colleagues are developing it for use on marginal, highly erodible lands similar to that currently in the Conservation Reserve Programs. All the fields in this study met the criteria that would have qualified for this program. Using a conservation cellulosic conversion value, researchers found that switchgrass grown on the marginal fields produced an average of 300 gallons of ethanol per acre compared to average ethanol yields of 350 gallons per acre for corn for the same three states.
The researchers point out that this was a base-line study. The switchgrass cultivars used in this study were developed for use in pastures. New higher yielding cultivars are under development for specific use in bioenergy production systems.
Switchgrass yields continue to improve, Vogel said. Recent yield trials of new experimental stains in the three states produced 50 percent higher yields than achieved in this study.
"Now, we really need to use an Extension effort to let farmers know about this new crop," Vogel said.
Future research will include further studies of improving management practices including work on improving establishment and harvesting methods, improving biomass yield, and improving conversion efficiency and net and total energy yields, Vogel said.
Switchgrass in this study employed UNL's best management practices for switchgrass, including no-till seeding, herbicides, weed control and adaptive cultivars. This study was also based on farm fields up to 20 acres instead of smaller research-scale plots typically less than about 100 square feet.
Six cellulosic biorefineries that are being co-funded by the U.S. Department of Energy also are in the works across the U.S. that should be completed over the next few years. These plants are expected to produce more than 130 million gallons of cellulosic ethanol per year, according to the U.S. Department of Energy.
One could also say that, assuming this study is right
It's EROEI is 1/3rd less than SugarCane.
So the primary question is, where is all this supposed biomass going to come from?
http://greyfalcon.net/biolimits.png
http://greyfalcon.net/perlack
Magic?
The Gov't likes to say switch grass can grow on poor soil, which is true. IF it can produce 540x the amount of energy that corn does, then we will we no longer be growing corn anywhere in the Great Plains. That will cause significant inflation in food prices world wide which will cause massive human starvation.
Using our food producing lands for the production of fuel has some very cruel consequences. How many dead people is gasoline independence worth? 5 million people? 20 million people? per year? What will the skin color of those people be?
EPM: While there is no ref to the original article, I assume this is an EROEI calculation, based on the FOSSIL inputs and equivalent energy outputs. In this case the 540% would merely show that with perennial switchgrass you actually capture a lot of solar energy, whereas with corn you are largely turning fossil fuel into slightly more fossil fuel replacement with little gain from the solar inputs.The difference is usually the reduction in fertiliser and other inputs with a perennial ( where a lot of the palnt is retained) rather than an annual ( where all the plant is discarded each year)
So the Laws of Thermodynamics are safe!
However I havent seen the original paper , nor who funded it ( which often affects the reported results) so they may be blowing smoke.
Mr. Mosman-
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The claim that witchgrass grown for biofuel production produced 540 percent more energy than needed to grow is in conflict with the two basic laws of thermodynamics which control all processes.
First Law- Energy is neither created or destroyed, it changes from one form to another.
Second Law- The energy available after a chemical reaction is less than that at the beginning of a reaction; energy conversions are not 100%
Have the researchers at the University of Nebraska-Lincoln (UNL) actually developed a perpetual motion process, one that creates the more energy that it takes to produce? If any process produces more energy than the process uses there would be no need for government subsidies of research, development and production, the private sector would fund all future developments.
If countries shifted there food-producing land to fuel-producing ones i think great problems regarding food availability and quantity will occure thus millions of persons will suffer. Look nowadays for corn and its prices which may proceed rising in the next years as we will produce more and more ethanol, many countries especially at Africa will suffer since they depend on such crop. So the solutions i think either producing such crops for fuel in non-cultivated areas under high plant density or shifting to othre alternatives such as Algae or other crops that don't occupy large areas.
The only solution is drastic demand reduction. Only then can we consider alternatives to meet our much reduced demands. We have designed a very wasteful system that becomes more wasteful every day. We've become dependent on ever increasing use of many finite resources - land, water, oil, etc. Read the Meadows report to the club of rome on the limits of growth.
One more thing. The vast majority of grain and soy grown in the US goes to feed livestock. We could achieve great increases in food system efficiency if we switched to a mostly vegetarian diet, and especially if we all had backyard gardens.
The article estimates that 30% of current gasoline demand can be met with switchgrass. If we ignore the impacts of using that much land to grow switchgrass, and current technological lackings in refinement... By the time they get the system up and running, demand increase for gasoline will have exceeded that 30% - so it leaves us no better than where we were before, only we won't actually have the same amount of gasoline we do now, because global production will be in decline due to oil field depletion.
When the author's write that "major cellulosic ethanol sources that could potentially displace 30 percent of current U.S. petroleum consumption," it is assumed that the reference is to gasoline, not the total of petroleum products , which is approximately 20,000,000 BBLs/DAY(42USG/BBL) Gasoline consumption in the US today is approximately 9,000,000 BBLs or 378,000,000 USG per DAY. The study reports the ethanol yield as 300USG per acre and a yield from six proposed plants of 130,000,000USG per YEAR, less than one-third of one day's consumption since ethanol has only two-thirds of the energy content of gasoline in BTUs/USG.