Ethanol vs. Biodiesel: Life Cycle Impacts
by Collin Dunn, Corvallis, OR, USA on 07.12.06
To add fuel to the fire that is the ongoing debate comparing the big two biofuels: ethanol and biodiesel (here's our first go at it). An analysis by University of Minnesota researchers of the full life cycles of soybean biodiesel and corn grain ethanol concludes that biodiesel has much less of an impact on the environment and a much higher net energy benefit than corn ethanol, but that neither can do much to meet US energy demand. The researchers tracked all the energy used for growing corn and soybeans and converting the crops into biofuels. They were fairly dilligent about the life cycle impacts, also looking at how much fertilizer and pesticide corn and soybeans required and how much greenhouse gases and nitrogen, phosphorus, and pesticide pollutants each released into the environment.
The study showed that both corn grain ethanol and soybean biodiesel produce more energy than is needed to grow the crops and convert them into biofuels. This finding flies in the face of other studies claiming that these biofuels require more energy to produce than they provide. The amount of energy each returns differs greatly, though: soybean biodiesel returns 93% more energy than is used to produce it; corn grain ethanol currently provides just 25% more energy.
Still, the researchers caution that these biofuels are not the silver bullet we're hunting to help insure a greener future; neither can come close to meeting the growing demand for alternatives to petroleum, but they think it's a good start. Alternatively, biofuels from feedstocks such as switchgrass, mixed prairie grasses and woody plants produced on marginally productive agricultural land or biofuels produced from agricultural or forestry waste have the potential to provide much larger biofuel supplies with greater environmental benefits than corn ethanol and soybean biodiesel. So, the jury may still be out on the efficiency and future of biofuels. via ::Green Car Congress
Algea biosdiesel and organic waste ethanol would have been a better thing to look at as they will be the future when people realise the current system is just a boost for corn/soya bean farmers.
It has been interesting to see the debate shape up between ethanol and biodiesel. Maybe if we use more corn for ethanol it won't be used in more insidious products like cow feed and corn syrup. If you're interested, I've also blogged a bit about ethanol and its use in Brazil: http://www.nextbillion.net/blogs/2006/06/16/more-thoughts-on-ethanol
http://www.nextbillion.net/blogs/2006/06/14/sugarcoating-petroleums-future
Regardless, something needs to be done fast. The main problem I see with petroleum, other than the environmental impacts, is that it is mostly imported. Even though ethanol gives a 25% energy gain, if we stepped up production and put more ethanol pumps up, then all of the profit made at every step of the way would be earned within the US, which would help our country out more.
If US consumers had more choices at the pump for their cars, and there was a coal tax, the impact we would have on the environment would be greatly reduced, oil consumption would be reduced, and consumption of other sources would be increased thereby decreasing the cost of gasoline.
Biodiesel is also more sustainable in the sense that it can be made from waste oil derived from fryer grease as well as grease trap. Therefore, limiting the amount of energy exterted to make the fuel, and also utilizing waste into a beneficial alternative energy. Biodiesel - NO WAR REqUIred!
Question: people always talk about the energy input vs. output of biofuels. Does anyone ever compare this to the same thing for petroleum. I know it takes a lot of energy to drill/pump/ship/refine etc.
I love it! Biodiesel and Ethenol from corn. Let the bidding begin. SUV,s and beltlines in competion. This could be the greatest slimming down of America ever. J.C., Sr.
why don't you talk about *algae*
it's so frustrating how wrapped up in themselves "green" types are, they don't listen
10,000 to 20,000 gallon of biodiesel per acre/year from algae. less than 60 cents/gallon.
source: http://www.unh.edu/p2/biodiesel/article_alge.html
soy and corn etc are a JOKE and so are people who talk about them while ignoring algae
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editor note: do a search in the top right corner for "biodiesel algae"
This finding flies in the face of other studies claiming that these biofuels require more energy to produce than they provide.
For all practical purposes, this statement isn't really true. While this study quantitatively contradicts Pimentel and Patzek's findings on corn ethanol (an energy return ratio of less than 1), it doesn't really change the picture. From a standpoint of fueling our culture, the difference between an energy return ratio of 0.7 and a ratio of 1.3 is pretty much nil.
The culture of cheap oil was built on easily-obtainable petroleum, which has an energy return ratio of somewhere between 5 and several hundred (depends greatly on the well; a ratio of 5 is a stripper well near end of life). In that context, making fuel with a return ratio of less than 2 is pretty much just busy-work.
Now, the other thing to consider is the difference between petroleum ERR and total ERR. Even Pimentel and Patzek's work suggests that it takes alot less than a gallon of petroleum to produce a gallon of ethanol (about 0.2, if I recall correctly). The remaining energy comes from natural gas, coal, or some other heat/energy source. So corn ethanol is a way to convert coal into liquid fuel, which is a process with a positive economic value, but a negative environmental value.
Diana:
They do. I believe the numbers I've heard are that it currently takes one gallon of oil to produce 10, down from a 100:1 ratio in the heyday of oil production.
Oil shale fares almost as badly as biofuels (1:1.5-1:2.5, depending on who you ask).
Vikash - no one went to war for oil, stop being silly.
Great job treehugger! You broke the story even before the New York Times. In Thursday's paper they have this article on the subject:
http://www.nytimes.com/2006/07/13/business/13ethanol.html
Bio fuel have a far better energy out put than oil or gas,
current figures on oil is for 1 gallan used in production and transportaion, you get 0.94 gallons of saleable fuel.
with ethanol from corn you get 1.26 gallans of saleable fule from 1gallon used in production and transportation
if you get the ethanol from sugar cane you up the saleable fuel to 1.96 gallons.
and it's just not economics to think about, think about the carbon impact of oil,
Biofuels such as biodiesel and ethanol, from a variety of food-based feedstocks offer air quality benefits, but there are concerns:
1. Currently, biofuels are not cost-competitive with conventional fuels without significant subsidies. Does it make sense to continue to subsidize food-based biofuels (read: compete with food supplies where high fructose corn syrup and soybean oil comprise a major source of human caloric intake, and subsidies finance industrial agricultural giants AND oil companies that have invested in biofuels), or should we be subsidizing things such as diesel retrofits, that will make diesel engines run as clean as natural gas, without competing with food sources, etc?
2. Soybean-based biodiesel results in enormous emissions of nitrous oxides - on part with CO2 emission from fuel combustion. Much of this comes from the nitrogen fertlizers used to grow soybeans and the release of microbially mediated nitrous oxides (from the soil). Including these emissions in a life cycle analysis (Delucchi is the only researcher I know of to date that does) may result in biodiesel emitting considerably more CO2 emissions than even petroleum diesel.
3. Food-based biofuels cannot begin to meet energy demands. Studies say even if all corn and soybean crops were dedicated to producing biofuels, it would result in displacing gasoline and diesel fuel by only 12% and 6% respectively.
4. Cellulosic ethanol and biofuels made from agricultural waste, from crops grown on marginal agricultural lands, with far less inputs (pesticides, fertilizers) than is presently used for food-based biofuel crops (corn, in particular, uses an emormous amount of both), represents a longer term solution with less environmental impact and greater net energy gains.
Biofuels such as biodiesel and ethanol, from a variety of food-based feedstocks offer air quality benefits, but there are concerns:
1. Currently, biofuels are not cost-competitive with conventional fuels without significant subsidies. Does it make sense to continue to subsidize food-based biofuels (read: compete with food supplies where high fructose corn syrup and soybean oil comprise a major source of human caloric intake, and subsidies finance industrial agricultural giants AND oil companies that have invested in biofuels), or should we be subsidizing things such as diesel retrofits, that will make diesel engines run as clean as natural gas, without competing with food sources, etc?
2. Soybean-based biodiesel results in enormous emissions of nitrous oxides - on part with CO2 emission from fuel combustion. Much of this comes from the nitrogen fertlizers used to grow soybeans and the release of microbially mediated nitrous oxides (from the soil). Including these emissions in a life cycle analysis (Delucchi is the only researcher I know of to date that does) may result in biodiesel emitting considerably more CO2 emissions than even petroleum diesel.
3. Food-based biofuels cannot begin to meet energy demands. Studies say even if all corn and soybean crops were dedicated to producing biofuels, it would result in displacing gasoline and diesel fuel by only 12% and 6% respectively.
4. Cellulosic ethanol and biofuels made from agricultural waste, from crops grown on marginal agricultural lands, with far less inputs (pesticides, fertilizers) than is presently used for food-based biofuel crops (corn, in particular, uses an emormous amount of both), represents a longer term solution with less environmental impact and greater net energy gains.
I must agree with the frustration of the anonymous poster of why not biodiesel algae. Now take the biodiesel created from algae then also take Hydrogen injection which cuts fuel consumption by 17%-90% usually closer to 50% and there's a pretty good source. Hydrogen injection is the key to standardizing bio-fuels look it's benefits up.
We found an interesting article about the problems with Ethanol on ConsumerReports.org:
http://blogs.consumerreports.org/cars/2008/03/ethanol-e85.html
"But there are some problems with increasing ethanol blends. Ethanol contains less energy than gasoline, so increasing the amount of ethanol in gasoline will likely result in lower fuel economy. Increasing standard fuel blends from zero to 10 percent ethanol, as is happening today, has little or no impact on fuel economy. In tests, the differences occur within the margin of error, about 0.5 percent. Further increasing ethanol levels to 20 percent reduces fuel economy between 1 and 3 percent, according to testing by the DOE and General Motors. Evaluations are underway to determine if E20 will burn effectively in today's engines without impacting reliability and longevity, and also assessing potential impact on fuel economy."
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