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March 01, 2006

New Ethanol Study

A new report by UC Berkley analyzes six studies of the energy efficiency of ethanol, adjusted all of the studies to consistent system boundaries for comparison and based on the current state of ethanol production recalculated the values for corn ethanol and used a "realistic scenario" conditions to calculate the energy to produce cellulosic ethanol from switchgrass. The study found that the net energy ratio (energy out/energy in) is 1.2 for ethanol produced from corn and 8.3 for cellulosic ethanol produced from switchgrass. The net energy value (energy out-energy in) was calculated to be 4.5 MJ/liter for corn ethanol and 22.8 MJ/liter for cellulosic ethanol.  In terms of environmental impact corn ethanol decreases greenhouse gases only 14% when compared to gasoline, while cellulosic ethanol has a much greater reduction of 88% . They also pointed out, as have others, that it takes less energy to produce ethanol than it does to produce gasoline.

The abstract from the report also states some of their other important findings.

To study the potential effects of increased biofuel use, we evaluated six representative analysis of fuel ethanol.  Studies that reported negative net energy incorrectly ignored coproducts and use some obsolete data.  All studies indicated that current corn ethanol technologies are much less petroleum-intensive than gasoline but have greenhouse gas emissions similar to those of gasoline.  However many important environmental effects of biofuel production are poorly understood.  New metrics that measure specific resource inputs are developed, but further research into environmental metrics is needed.  Nonetheless, it is already clear that the large-scale use of ethanol for fuel will almost certainly require cellulosic technology.

The reports that they found erroneous were one by Patzek and and one by Pimental and Patzek.

First of all I hope this report, by an independent organization, will once and for all put to rest the controversy as to whether the net energy value is positive or negative. My support of ethanol for fuel is reinforced by this report.  I see some disruptive times in switching from corn ethanol to cellulosic ethanol which is required to both conserve energy and to produce enough ethanol without compromising our food supplies.  It is also true that it is more efficient to burn the feedstock in a CHP (combined heat and power) generator and use the electricity to power EV's and plug-ins.  This possibly presents another difficult transition in that, at the present time and for the next 15-25 years, our vehicle fleet will be primarily dependent on liquid fuels and we will need all the ethanol we can produce in order to help keep the price of fuels under control.  Our ethanol production capacity is rapidly ramping up to help meet this need and possibly could supply 20% of our liquid fuels by 2020.  By that time gasoline will no doubt cost over $5.00 per gallon compared to less that $3.00 (more likely $2.25) per gallon for ethanol (in 2005 dollars).  Cellulosic Ethanol as being developed by Colusa, Iogen, and Xethanol, or alternately the BRI process should be in commercial use by 2010. Whether to use biomass to make vehicle fuel or for CHP fuel will be the question after 2020-25.  There is also the possibility that by this time the gasification/Fischer-Tropsh processes (BTL) such as the Shell/Choren process will be used to produce both electricity and fuel.  At this time it is not clear to me how this will shake out and I will return to the subject later in the year.  I am sure the Engineer Poet will have a comment at this time.

The paper which was published in Science and the spreadsheet model used to develop the data as well as links to the six studies that were compared are found here: ERG Biofuel Analysis Meta-Model

Green Car Congress and After Gutenberg have also had posts on this report, with emphasis on other aspects of the report which you may want to visit.

Recent Berkley Study: Corn Ethanol is Better Than Gasoline, But Not by A Lot, Green Car Congress, Jan. 26, 2006
UC Berkley Study Boosts Cellulosic Ethanol, After Gutenberg, Jan. 26. 2006

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This study corroborates the findings of a study made last year (BEFORE PIMENTAL's release of his erroneous study) by Michael Wang of the Center for Transportation Research of the University of Chicago/Argonne National Laboratory (work sponsored by the U.S. Department of Energy). http://www.anl.gov/Media_Center/News/2005/NCGA_Ethanol_Meeting_050823.ppt.

Corn and sugar fermentation have been invaluable at helping build our current infrastructure for ethanol (2% of our national liquid fuel consumption is better than 0%). It has also spurred marketing of flex-fuel vehicles and established the 800 stations that offer E85.

But we can do much better with conversion technology (CTs) and regional solutions based on regional feedstock assets. Fossil fuels can also be used in the CTs for the creation of celluosic ethanol. Blending of CT feedstock can produce optimized output results for each region and may develop interesting electricity co-generation solutions.

I would like to see co-siting of CTs with the 85+ existing sugar refineries. That will allow a smooth transition for farmers who would then be able to convert ag waste, switch to other crops, and help profit even with foul harvests.

Biofuel seems increasingly prosperous. In a recent comment by a professor of The Royal Veterinary and Agricultural University, Denmark, he states that just 16% of Danish farmland could supply ethanol to replace our entire consumption of gasoline! This prognosis included improvements already in the pipeline for the enzymes that break down the cellulosis.

About biofuel in CHP. We have quite a lot of that in Denmark, but I'm personally growing increasingly sceptical. Burning straw is not only technically difficult, because of e.g. hydrocloric acid, but a lot minerals are removed from the soil, only to end up as harmful deposits in the boiler. All these minerals need to be replaced in the soil, usually by fertilizer.

What I like so much about making ethanol is the fact that only the hydro-carbon (which came from sunlight, water and CO2 captured from the atmosphere) is removed. There will be an end by-product that contains all the minerals that the plant had originally taken from the soil. These minerals can probably be re-applied to the soil, thus greatly reducing the need for energy-intensive fertilizer.

This process is much more like the process in a cow's stomach and, as we know, cow manure is excellent fertilizer.

Actually there are other processes to seperate manure into water, hydro-carbon and minerals (left over fertilizer). This left over fertilizer is actually more efficiently absorbed by plants than artificial fertilizer. But that's a whole other discussion.


I hope that in the push to ramp up biofuel production, we don't forget about the sytems supporting the feedstock. Thomas' point is critical. What water and soil problems will we see if California goes full steam ahead on corn based ethanol. Are there not major water and soil conservation issues there already?

C. Scott Miller - The Wang study you referred to was one of the six reports that were analyzed. I did not list the studies because I only wanted to make my main point. Other blogs have listed all six studies.

What is switchgrass? How many acres of farmland would be required to produce a barrel of oil equivalent from switchgrass? From corn? From sugar cane?

This begs the question of what will we eat if we use a significant fraction of farm land for fuel production?

Halvo - The problems you pointed out are true for corn ethanol, but not as severe for cellusosic ethanol made from swithgrass or Miscanthus grass. They will grow on marginal land and control errosion, require little or no fertilizer and are drought resistant.

G. Eddy - Switch grass is a perannual grass that grows very tall, lives for 10 years or more, thus not requiring the energy input from planting every year. It does not require any cultivation, no fertilizers, is drought resistant and controls errosion. Very similar to Miscanthus grass referred to in the above comment. I don't remember the yield per acre for corn ethanol, but it is much less than for the grasses. Cellulosic ethanol can also be made from forestry waste. A ORNL study, made last year, concluded that we could obtain 30% of our liquid fuels from biomass without compromising out food production.

Great work here. There is much more potential than the nay-sayers think. When you consider all of the unused land available(some of which our farmers are collecting revenue not to farm!) we could put a serious dent in traditional oil requirements.

What water and soil problems will we see

If there is no provision for returning the 'waste' organic material back to the land, the eventual effect will be a stripping of the micro elements and the destruction of the soil food web via the starvation of many of the symboitic fauna the flora needs to grow and prosper.

Switch grass is a perannual grass that grows very tall, lives for 10 years or more, thus not requiring the energy input from planting every year. It does not require any cultivation, no fertilizers, is drought resistant and controls errosion.

Please double check the 'no fertilizer' claim. Most of the data I've seen says 'light' nitrogen, and I've not seen any data showing what happens with you harvest the grass without returning ash or the dead grass back to the land.

Otherwise - spot on.

corn ethanol,

The corn idea exists to provide a 'demand floor' for corn.

Great work here. There is much more potential than the nay-sayers think.

But unless 'the plan' puts back the organic material left over from obtaining 'liquid energy', what WILL happen is, over time, the land will eventually unable to support plant life.

To get the 'waste' back to the land, the closer the process of biobits to fuel is to the growers of the biobits, the more likely it is the 'waste' will return to the soil.

'the ideal plan' would put the energy extraction process right on the biobits growers property. Then the bio-bit farmer can sell off excess capacity and would be responsible for 'closing the waste loop'.

So unless you are pushing the return of 'organic waste' material to the land switchgrasslover,

Oh, I almost forgot. People are treating the production of Ethanol like it is either a 'corn' or 'switchgrass' solution.

Personally, I'm growing sugar beets for making sugar-squeezings. The chipped beet? Fodder for the various critters and goes right back on the land as compost.

And this solution is 'only one farm'-style solution.

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