Ethanol vs. Electricity: Biomass converted into electricity could be more efficient than ethanol (w/Video)

May 07, 2009
Ethanol vs. Electricity. Credit: McDade & Campbell/UC Merced

(PhysOrg.com) -- Concerns over petroleum gas prices and long-term effects of greenhouse gas emissions on the environment have prompted scientists to look for alternative renewable energy sources for transportation use. One of the questions at hand is determining what that preferred technology should be.

Scientists are examining - plant matter that's grown and used to generate energy - as a potential power source. Two biomass technologies involve ethanol and . Biomass converted into ethanol, a corn-based fuel, can power internal combustion vehicles. Biomass converted into electricity can fuel a vehicle powered by an electric battery.

A study by University of California, Merced, Assistant Professor Elliott Campbell and two other researchers in the May 8 issue of the journal Science suggests that biomass used to generate electricity could be the more efficient solution.

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Biofuels such as ethanol offer an alternative to petroleum for powering our cars, but growing energy crops to produce them can compete with food crops for farmland, and clearing forests to expand farmland will aggravate the climate change problem. How can we maximize our “miles per acre” from biomass?

In the study, Campbell, along with Christopher Field of the Carnegie Institution's Department of Global Ecology and David Lobell of Stanford University, the scientists found that biomass converted into electricity produced 81 percent more transportation miles and 108 percent more emissions offsets compared to ethanol.

In other words, said Campbell, vehicles powered by biomass converted into electricity "got further down the road" compared to ethanol. As a result, Campbell continued, "we found that converting biomass to electricity rather than ethanol makes the most sense for two policy-relevant issues, transportation and climate."

The scientists based their study on two criteria: miles per area cropland and offsets per area cropland. In both cases, scientists considered a range of feedstock crops (corn and switchgrass0 and vehicle types (small car, midsize car, small SUV and large SUV.

First, they looked at how many miles a range of vehicles powered by ethanol could travel versus a range of electric vehicles fueled by electricity. Second, they examined offsets to greenhouse gas emissions for ethanol and bioelectricity. Land use is an important factor to consider when evaluating each method. Globally, the amount of land available to grow biomass crops is limited. Using existing croplands for biofuels could cause increases in food prices and clearing new land, or deforestation, can have a negative impact on the environment.

The authors are careful to point out their study looked at two criteria, transportation and greenhouse gas offsets, but did not examine the performance of electricity and for other policy relevant criteria.

"We also need to compare these options for other issues such as water consumption, air pollution and economic costs," Campbell said.

Campbell joined UC Merced as an assistant professor in the School of Engineering in 2008. He earned bachelor's and master's degrees at Stanford University and his Ph.D. from the University of Iowa. Prior to joining UC Merced, Campbell received national attention for another study that concluded the United States Could meet up to 6 percent of its energy needs with biofuels produced on abandoned or degraded agricultural land.

More information: A copy of Campbell's abstract can be viewed online at sciencemag.org/

Source: University of California - Merced

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User comments : 10

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DozerIAm
1.8 / 5 (5) May 07, 2009
now the 2 questions are:

1) what crop can we grow that will produce the largest mass of harvest with the least fertilizer, pesticide and water needed?

2) will the corn lobby and the politicians beholden to them work like crazy to supress any studies or movement in this direction?

(why yes, I am a pessimist, how did you know?)

jaggspb
2.2 / 5 (5) May 07, 2009
I agree Dozer. Substituting the AgroLobby for the OilLobby gets the people nowhere.
PPihkala
4 / 5 (1) May 07, 2009
For me the messages are clear:

1) don't make ethanol
2) use fossil based transportation fuels, not ethanol
3) burn non-edible plants to make electricity instead of using fossil fuels
4) replace vehicles with ones using electricity

Dozer: I think that answer to your 1) question will be algae. There has been news about algae energy use recently.
Thadieus
4 / 5 (1) May 07, 2009
Has any one heard of David Blume? I heard him on a radio show a couple of times. He promotes distilling certain crops to alcohol and using it for gas. He really seems like he knows what he's talking about and has seeming has good answers to the obvious problems. His web site is http://www.permaculture.com/ perhaps someone with more intelligence can peruse his ideas and say yea or nay.
Lord_jag
not rated yet May 08, 2009
When I see the biomass rotting in the median on the highways and the amount of biomass left on the curb whenever we have leaf and branch pickup days, its shocking to me that we couldn't make that into some form of usable energy.

Of course collection would likely use as much or more energy as could be collected, but meh. It's got to be collected anyways
david_42
5 / 5 (1) May 08, 2009
One major downside of using biomass of any sort for energy production, removing the mass from the land reduces soil fertility and increases the requirements for manufactured fertilizer.
DozerIAm
1 / 5 (1) May 11, 2009
Wow, my post seems to have irked some folk. Lord_jag | Rick69 | GrayMouser - I'd appreciate knowing what it was about the post you didn't like. Pretty sure my question #2 wasn't being political in a one sided way, my question #1 was entirely valid. Not looking for a fight, just enlightenment. :)

JLMEALER
May 11, 2009
This comment has been removed by a moderator.
lengould100
4 / 5 (1) May 12, 2009
Photosynthesis efficiency in conversion of insolation to harvestable chemical potential energy = 1% in temperate climates with good fertility and rainfall. After harvesting, chipping, torrefaction, transport to power plant, use 0.05%. Then burn in a 33% efficient boiler -> steam turbine, 0.05% x 33% = 0.0165% overall efficiency, insolation to electricity.

Means that, AT ANY GIVEN LOCATION, a 15% efficient solar-thermal plant can do the same job with 0.0165/15 = 0.0011 the area of the biomass plantation.

So which is better? 1 sq km of solar thermal which never needs re-planting and doesn't permanently damage anything, or 909.1 sq km of biomass plantation which depletes the soils, etc. etc. ? (HINT: the answer is solar thermal OR PV -> electrical)
jerryd
not rated yet Jun 07, 2009

While one can say that they would have to ignore the fact that after ethanol is made most of the biomass is still there in the leftover mash, corn stalks, cobs. So one can both have ethanol and burn wht's left for electricity.
Also left out is the mash is a better animal or even human feed than raw corn is.
Gasoline if taken by the same poor standard would be even less eff as one only gets about 1/4 of the output from the product.
And one can FT the biomass into gasoline, diesel which Shell, Syntroleum has already done but doesn't sell their GTL units so people could.
Taken together ethanol is no worse than other fuels and better than many.
A combo of NG, Ethanol, bio gasoline/diesel and EV's will be our future, especially EV's as they are 3x's as eff as any fueled car.
Which is why I built my EV. Sadly about the only way to get one. My 3wh service car style EV gets 600mph equivalent and my 2 seat EV sportswagon gets 250mpge.
The costs of oil are huge from pollution, CO2, subsidies, balance of payments, $500B/yr which go to our enemies like Iran, Russia, oil dictators and terrorist means ethanol and EV's, RE like wind, solar thermal, river/tidal power without dams, ect are very cheap comparatively.
WE need them all with eff, conservation and get rid of coal and imported oil. Oil hit $70 on 6-5-09 and going up with a bullet as the economy recovers will hit 150/bbl again by late next yr, 2010.
DozerIAm
1 / 5 (1) Jun 08, 2009
My 3wh service car style EV gets 600mph equivalent...


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