Part 2: Disputing Pimentel’s Ethanol Research

 

This is the second article in a three part series that focuses on debunking the myth that ethanol production creates a net energy loss.

Last weeks article focused on this myth’s origin and its strongest supporters  David Pimentel and Tad Patzek.  This week will focus on debunking the some of the inconsistencies found in their research compared to the results of other studies done on ethanol energy outputs, and it will discuss some of the key energy omissions from Pimentel’s/Patzek’s 2001 study.

Below is  a  list of the Pimentel Study’s most glaring problems along with rebuttals to why they are problems.

1. Pimentel – Ethanol production yields a 29% loss in energy when produced from corn
•    The U.S. National Renewable Energy Lab found a producing ethanol yielded a 30% gain in Energy when comparing 1BTI of fossil fuel to 1BTU ethanol.  This study was done shortly after Pimentel’s Study.
•    In the National Renewable Energy Laboratory (NREL) 2010 report Current State of the U.S. Ethanol Industry the NREL finds the following
1.  The net energy balance of corn ethanol has increased from 1.76 BTU’s to 2.3 BTU’s since 2004.
2.  For every BTU of energy required to make ethanol, 2.3
   BTU’s of energy are produced.
3. Over the past 20 years ethanol yields have increased over 10% and corn yields have increased 39%.
2. Pimentel – Between 45% to 57% more energy would be lost in producing ethanol from wood or switchgrass
•    The United States Department of Agriculture conducted a study on switchgrass and found that it had a 540% energy yield, meaning it produced 540% more energy than it took to produce it.
3. Pimentel’s study uses outdated information or incorrect  data
•    Pimentel uses data for corn yields that exists before 1992.
•    Pimentel uses values for measuring energy to produce ethanol that were used in the 1980′s.
•    Pimentel uses 1990 world-wide values, not recent U.S. values for his figures determining how much energy is needed to produce fertilizer.
4. Pimentel’s study omits crucial data that could help determine ethanol’s energy production
•    Pimentel does not factor in dried distiller grains into ethanol’s energy output.  1/3 of all ethanol produced gets reused as distiller grains, which in turn is used to make animal feed.  This is huge source of energy not included in Pimentel’s study.

Pimentel’s study has many flaws making it an unreliable source of information.  His findings have been discredited by many scientists and government agencies within the U.S.  Next week will be part three of this series which will discuss the energy ethanol is currently producing and what the ethanol industry is expected to produce.

 

Sources:

Pimentel/Patzek Article Oil Ties and Arguments  http://www.biofuelsjournal.com/articles/ethanol_industry_refutes_david_pimentel_s_study_showing_negative_energy_balance_for_ethanol-27165.html

2002 U.S. Department of Agriculture Study http://journeytoforever.org/ethanol_energy.html

Pimentel Claims: http://www.freelists.org/post/biofuels-forum/Key-Differences-between-PimentelPatzek-Study-and-Other-Studies,1

http://journeytoforever.org/biofuel_library/PimentelComments4_5_05.pdf

National Renewable Energy Laboratory See Section 7.1 Net Energy Balance http://www.nrel.gov/analysis/pdfs/doe-02-5025.pdf

USDA Switchgrass yields http://www.scientificamerican.com/article.cfm?id=grass-makes-better-ethanol-than-corn

U.S. Ethanol Distiller Grains http://growthenergy.org/images/reports/ethanol_livestock.pdf

Part 1: Does Ethanol Cost More Energy to Produce than to Use?

Does ethanol cost more energy to produce than to use?

Since the ethanol industry has been the first industry to prominently challenge the oil industry in the U.S. over the fuel market in almost a century a lot of criticism has been thrown towards ethanol.  Ethanol costing more energy to produce than to use has been one of the most common attacks against the ethanol industry.  This statement is not true and this three part series of blog articles looks to show you the origins and motivations behind this idea, debunking the data and discovering the flaws of the research behind ethanol costing more energy to produce than to use,  and eventually to show that ethanol can produce more energy than is used to produce it.

The biggest contributor towards the “ethanol produces a loss in energy” fallacy was written by University of Cornell Professor of Entomology David Pimentel and University of California, Berkley, Professor Tad Patzek in 2001.  Pimentel’s research is frequently used by supporters of the oil industry to try and bring down the credibility of ethanol as a source for fuel.  Furthermore their claims don’t stack up to the research that has been done by other scientists.

The only other studies that show ethanol costing more energy to produce than to use are all done in the 1980′s and early 1990′s.  It is possible that ethanol may have cost more energy to produce during those times but technology has improved since then even by the time Pimentel’s study had gone underway.  A year after Pimentel’s study was released the U.S. Department of Agriculture found that ethanol gives 34% more energy than it takes to produce it.  Below is a graph showing how Pimentel’s results aren’t matching up with current ethanol studies.

Pimentel’s study features a number of disputed claims and other problems in regards to how the experiments were performed and what they did and didn’t factor in.  These problems/disputed claims are:

• Ethanol production yields a 29% loss in energy when produced from corn
• Between 45% to 57% more energy would be lost in producing ethanol from wood or switchgrass
• Pimentel’s study uses outdated information and data
• Pimentel’s study uses data incorrectly
• Pimentel’s study omits crucial data that could help determine ethanol’s energy production

Further hurting the Pimentel and Patzek study is Patzek’s connections with the oil industry.  At the University of California Patzek is the director of the schools oil consortium which is financially backed by Chevron and Phillips.  He also worked at Shell for over decade as a research consultant and expert witness.  These ties to oil indicate a bias in their study towards the oil industry, which has been working to remove ethanol from the fuel market, securing it exclusively for themselves.

Part 2 in this series will be focused on debunking Pimentel’s results and showing how some of the data collected from Pimentel’s research was old or outdated.

 

Sources:

Pimentel/Patzek Article Oil Ties and Arguments  http://www.biofuelsjournal.com/articles/ethanol_industry_refutes_david_pimentel_s_study_showing_negative_energy_balance_for_ethanol-27165.html

2002 U.S. Department of Agriculture Study http://journeytoforever.org/ethanol_energy.html

Pimentel Claims: http://www.freelists.org/post/biofuels-forum/Key-Differences-between-PimentelPatzek-Study-and-Other-Studies,1

http://journeytoforever.org/biofuel_library/PimentelComments4_5_05.pdf

National Renewable Energy Laboratory See Section 7.1 Net Energy Balance http://www.nrel.gov/analysis/pdfs/doe-02-5025.pdf

USDA Switchgrass yields http://www.scientificamerican.com/article.cfm?id=grass-makes-better-ethanol-than-corn

U.S. Ethanol Distiller Grains http://growthenergy.org/images/reports/ethanol_livestock.pdf

Dry Mill Ethanol Efficiency Gains http://www.ethanolrfa.org/exchange/entry/from-farm-to-biorefinery-ethanol-production-efficiency-improves/

Dry Mill Ethanol Efficiency (Thermal Energy) http://www.ethanolrfa.org/news/entry/dry-mill-ethanol-production-shows-significant-improvements-in-efficien/

2.1.1.1 DGS in the U.S. http://www.transportation.anl.gov/pdfs/AF/527.pdf

 

Switchgrass Has Great Alternative Energy Potential

 

Switchgrass is a type of wild prairie grass that grows abundantly in the United States.  It’s so abundant that the only four U.S. states you can’t find switchgrass are California, Oregon, Alaska, and Washington.  At the turn of the 20th century an increased number of scientific studies have found that switchgrass could be used  to make biofuels, biogas, and cellulosic ethanol.  These alternative fuels can be made cheaper and more energy efficient.  As more research continues to improve the energy output of switchgrass, and because its very durable and abundant, switchgrass makes a strong economical choice for an alternative fuel.

Economically speaking switchgrass is a highly adaptable strong crop that’s already abundant.  Switchgrass has great longevity, it can resist floods and droughts,  it can grow in poor soil (sand and gravel based soils have supported switch grass), and it can grow in versatile climates (see the map above).  Furthermore it requires a small amount of herbicide and fertilizer which decreases the cost to grow it as a crop.  Switchgrass is also non-edible so producing it and worrying about whether or not the crop should be used as fuel or food is no longer a part of the debate.

Switchgrass doesn’t require a lot of water to grow it either.  Mariano Martin, a doctoral researcher at Carnegie Mellon found that switch grass uses less than a gallon of water to produce a gallon of fuel that is made from switchgrass.  Oil by comparison used 1.5-2.5 gallons of water to produce 1 gallon of oil based fuel.

Switchgrass is energy efficient too.  The USDA along with mid-western farmers experiment on growing switchgrass as a crop.  Crops were grown on fields between 7 and 23 acres in size and produced between 5 and 11 metric tons of grass bales.  Furthermore 13.1 megajoules of energy were produced for every megajoule of oil based energy consumed, when the switchgrass was converted to ethanol.  That’s 540% more energy produced by switchgrass than what is needed to produce it.

New research focused on increasing energy outputs of switchgrass are also being conducted.  The Department of Energy recently inserted a gene called Corngrass1 (CG1), which is used in corn, into the genetic makeup of switchgrass.  The gene keeps switchgrass in a juvenile state, making it easier to breakdown.  The genetically modified switchgrass yields more than 250% more starch, and it also makes it easier to extract polysaccharides and convert them into fermentable sugars.

As the technology for converting switchgrass into fuel advances; production of alternative based fuel increases.  As I mentioned in a previous article about cellulosic ethanol there are, as of Spring 2011, 38 cellulosic ethanol plants that have been constructed or are under construction in the U.S. and Canada.  9 of these plants plan on producing ethanol by using switchgrass as a feedstock.

Moving towards a brighter future, switchgrass promises be a great new source for producing alternative energy and fuel.

 

Sources:

Location of Switchgrass in North America: http://plants.usda.gov/java/profile?symbol=PAVI2

USDA and Midwest Farmer Experiment: http://www.scientificamerican.com/article.cfm?id=grass-makes-better-ethanol-than-corn

Corngrass1 Research http://www.sciencedaily.com/releases/2011/11/111118151414.htm

Carnegie Mellon Research http://www.thebioenergysite.com/news/10009/fuels-from-grass-researchers-explore-alternatives