SWITCHGRASS UPS ITS EROEI
While the U.S. Department of Energy (DOE) just backed out of a “clean” coal pilot project, it is moving forward on R&D of cellulosic ethanol production. It is funding 6 biorefinery plants around the country and research projects into swtichgrass and biomass efficiency. Its goal is to produce 130 million gallons of biomass ethanol yearly.
It has widely been claimed that switchgrass-derived ethanol has a positive EROEI while corn-derived ethanol’s EROEI is at best very low and likely negative. EROEI is “Energy Returned on Energy Invested.” The higher the EROEI, the better the raw material for fuel production. In the heyday of oil production, its EROEI was 100 or more (100 units of energy for every 1 expended in production). Oil now is down around 10 or less. (Much more on this is available at The Oil Drum)
This study validates the switchgrass side of the equation but, due to limitations of refining technology, the switchgrass only matched but did not surpass corn ethanol.
The study found switch grass had 93% more biomass per acre and net energy yield than had been found in a previous Minnesota study. Switchgrass and other perennial bioenergy crops therefore require less land. They also require less water.
The study, done on marginal farm fields rather than developed farmland, showed switchgrass producing 300 gallons of ethanol/acre. Corn on developed farmland produces 350 gallons/acre (in the 3 states where the study was done). The researchers therefore presently recommend switchgrass only for marginal lands and corn for developed farmlands.
The 3 major sources of ethanol currently under development. (From a lecture presentation by CalTech's Prof. Arnold - click to enlarge)
Study reports major net energy gain from switchgrass-based ethanol
January 18, 2008 (Tri-State Neighbor/S.Dakota Farm Newspaper)
Researchers at the University of Nebraska-Lincoln (UNL) (Ken Vogel, U.S. Department of Agriculture (USDA)-Agricultural Research Service(ARS)/UNL agronomy and horticulture department geneticist; Richard Perrin, UNL agricultural economist; Marty Schmer, USDA-ARS agricultural science research technician/UNL doctoral student; Robert Mitchell, USDA-ARS/UNL agronomist)
New research calculations has switchgrass ethanol producing 540% more energy than is used in growing, harvesting and processing it.
The new study moves switchgrass up a notch. (click to enlarge)
- The study was conducted over 5 years.
- Reported in January 7-11 Proceedings of the National Academy of Sciences.
The study was done on 10 15 to 20 acre marginal farm fields in 3 states (Nebraska – 4 near Atkinson, Crofton, Lawrence and Douglas; South Dakota – 4 near Highmore, Bristol, Huron and Ethan; North Dakota – 2 near Streeter and Munich)
Switchgrass is one of many natural grasses that need to be studied. (click to enlarge)
- This is the largest study to date on net energy output, greenhouse gas emissions, biomass yields, agricultural inputs and estimated cellulosic ethanol production from switchgrass grown and managed for biomass fuel.
- This was considered a “base-line” study. Larger yields are expected from future studies.
- Future research will be into how to better manage crops to improve yields.
- Biorefinery technology is presently being developed to break corn, switchgrass and other biomass down to sugars that can be used to make fuels.
- The researchers believe cellulosic substances from switchgrass to waste biomass could generate up to 30% of U.S. liquid fuel needs.
Switchgrass is an energy source superior to corn from its roots up. (click to enlarge)
- Vogel, USDA/UNL: “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, USDA/UNL: “…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, USDA/UNL: “UNL and the USDA-ARS have been pioneers in switchgrass research since the 1930s, domesticating it as a pasture grass…”