Is Ethanol Energy-efficient?
Not only is ethanol from sugar fermentation energy-efficient, but cellulosic ethanol from syngas fermentation is even more efficient since many factors regarding feedstock fertilization and transport are not included.
Another key finding is that ethanol has a positive benefit in greenhouse gas (GHG) emissions reduction. On a per gallon basis, corn ethanol reduces GHG emissions by 18% to 29%, while cellulosic ethanol has an even greater benefit with an 85% reduction in GHG emissions.
Below are excerpts from the Journey to Forever/Biofuels website.
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Is ethanol energy-efficient?
One of the most controversial issues relating to ethanol is the question of what environmentalists call the "net energy" of ethanol production. Simply put, is more energy used to grow and process the raw material into ethanol than is contained in the ethanol itself?
New study confronts old thinking on ethanol's net energy value, 3/28/2005 -- Ethanol generates 35% more energy than it takes to produce, according to a recent study by Argonne National Laboratory conducted by Michael Wang. The new findings support earlier research that determined ethanol has a positive net energy balance, according to the National Corn Growers Association. That research was conducted by USDA, Michigan State University, the Colorado School of Mines, the Institute for Local Self-Reliance and other public and private entities. A USDA study released in 2004 found that ethanol may net as much as 67% more energy than it takes to produce. Argonne is one of the US Department of Energy's largest research centers.
Updated Energy and Greenhouse Gas Emission Results of Fuel Ethanol by Michael Wang, Argonne National Laboratory
Key points of the study.
4 comments:
C. Scott Miller asked, "Simply put, is more energy used to grow and process the raw material into ethanol than is contained in the ethanol itself?"
The answer is almost as simple as the question.
The ethanol industry will have proved making ethanol -- especially corn ethanol -- returns more energy than its production consumes the day the ethanol industry doesn't need energy from fossil fuels to make ethanol. Do you see that happening anywhere in the country?
if making ethanol returns more fuel than it consumes, why don't ethanol plants run themselves on some of the ethanol they make instead of burning natural gas? Why don't farmers run their ag equipment on ethanol instead of diesel fuel?
The hard truth is that ethanol production would soon fizzle to a stop if it didn't constantly consume energy in the form of fossil fuels.
At every step of its production process, "renewable" corn ethanol consumes unrenewable fossil fuels:
1. Natural gas to make the nitrogen fertilizers corn farmers must have.
2. Diesel fuel for corn farmers to cultivate, plant, harvest, and transport their crops.
3. Diesel fuel to transport fertilizers, seed corn, and finished ethanol.
4. More natural gas on the farm to dry corn; more at the ethanol plant to mill and distill corn into ethanol; and still more to dry the waste distiller’s grains after fermentation.
Making corn ethanol is not presently possible without burning irreplaceable, unrenewable fossil fuels.
Until corn farmers and ethanol plants show that instead of using fossil fuels they can use ethanol as the energy source for growing more corn and turning it into ethanol, it is incorrect to call corn ethanol a “renewable” fuel.
Until that day, it is also incorrect to say ethanol returns more fuel than it consumes.
By some accounting methods ethanol does return more energy than it uses, but energy and fuel are not the same. All fuel is energy, but not all energy is fuel.
Unforunately much of the energy from making corn ethanol is locked in a waste by product of fermentation called distiller's grains (About 9600 Btu per pound.)
At a microscale of a handful of ethanol plants in each state, local cattle farmers can make good use of distiller's grain for feeding ruminants, but on a macroscale with hundreds or thousands of ethanol plants across the country, no one could use -- or get rid of -- all the distiller's grain that would pile up.
Excess energy would be locked in vast heaps of waste distiller's grain piled around ethanol plants. Ethanol plants would soon look like old coal mines surrounded by slag heaps, only these slag heaps would be piles of distiller's grain.
I defer to the Argonne National Laboratory's research results which are very clear in their opinion that ethanol produced via sugar fermentation generates a net energy surplus (approx. 35% more than it consumes).
In many states, ethanol is mandated as an oxygenate so its price or energy cost is almost a moot issue.
However, I am personally more optimistic about the syngas fermentation of cellulosic ethanol than I am on the reality of existing sugar fermentation. It doesn't consume as much fossil fuel in fertilization, farming, and transport as sugar fermentation does.
We have many problems in this country beside dependence on fossil fuel - waste management being an important one. Waste, as a feedstockl, is comparatively free since it has to be dealt with one way or another and it doesn't have to be grown. When we have syngas fermenting plants co-sited at MRF facilities - generating ethanol and green electricity from MSW, autofluff, tires, etc. - we will not only reduce fossil fuel useage for transporting waste, but we will also reduce landfill growth, field spreading of sewage, and other costly problems. The ethanol and green electricity netted is a bonus.
Thanks for writing.
C. Scott Miller said, "I defer to the Argonne National Laboratory's research results which are very clear in their opinion that ethanol produced via sugar fermentation generates a net energy surplus (approx. 35% more than it consumes)."
I've read the Argonne study also.
But doesn't it strike you as being the least bit curious that if ethanol returns more energy than is invested in it, that the ethanol production process is unsustainable without an injection of fossil fuel energy at each and every step of the production process -- from making fertilizers, to on the farm, to at the ethanol plant, to transporting fertilizer, corn, and finished ethanol?
If the Argonne study is correct, something is out of whack with how farmers grow corn and ethanol plants convert it to ethanol.
If I ran an ethanol plant and had read the Argonne study, I'd be asking hard questions about why I needed to burn natural gas to run my plant and why I couldn't run it on some of the ethanol the plant produced.
Any system that produces more energy than it uses, shouldn't be dependent on fossil fuels as are corn farming and the ethanol business.
Best wishes,
Gary Dikkers
Corn sugar fermentation - This is a "chicken or egg" situation. The farm world is dependent on fossil fuels precisely because fossil fuels have been the basis of the paradigm that has developed and dominated the last 100 years. Tractors, trucks, and fertilizers technology have been built on this paradigm during that time. To switch to ethanol will require a gradual phasing in of new fuels and infrastructure using the fossil fuel infrastructure that precedes it. That is what happens during a paradigm shift (typewriters were used to put the first word processors into the market). Part of the shift would include the substitution of biodiesel for petroleum diesel.
As I said, I am more interested in...
Syngas fermentation - Waste conversion of cellulosic feedstock is not dependent on the fossil fuel paradigm to the extent that sugar fermentation is. That was another Michael Wang finding. No seeds to distribute and plant, no feedstock growth to fertilize, no fields to level and plow. Also, less shipping since there would be more flexibility in the distributed siting of plants. The gasifiers do currently ignite with natural gas but alot of the BTUs in the process comes from burning the waste itself. Over time I am sure that more efficient use of the output of syngas fermentaton will be used to produce it. It already co-generates more electricity than it uses.
Happy New Year!
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