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Study Finds Bioelectricity Better Option Than Liquid Biofuels for Transportation Output and GHG Emissions

Campbell
Kilometers per crop hectare for switchgrass feedstock with a small SUV. Campbell et al. (2009) Click to enlarge.

A new life cycle assessment comparing the performance of bioelectricity and ethanol from a variety of pathways with respect to transportation kilometers and GHG offsets achieved per unit area of biofuels cropland concludes that bioelectricity used to charge a battery electric vehicle outperforms ethanol for a combustion engine across a range of feedstocks, conversion technologies, and vehicle classes.

The study by University of California, Merced, Assistant Professor Elliott Campbell along with Christopher Field of the Carnegie Institution’s Department of Global Ecology and David Lobell of Stanford University, found that bioelectricity produces an average 81% more transportation kilometers and 108% more emissions offsets per unit area cropland than cellulosic ethanol. A paper on the work appeared in the 8 May issue of the journal Science.

The authors point out their study looked at only two criteria, kilometers travelled and greenhouse gas offsets, but did not examine the performance of electricity and ethanol for other policy-relevant criteria such as water consumption, air pollution or economic costs.

“We found that converting biomass to electricity rather than ethanol makes the most sense for two policy-relevant issues, transportation and climate.”
—Elliott Campbell

In the assessment, the team used The Energy and Resources Group Biofuel Analysis Meta-Model (EBAMM) to consider scenarios covering a range of feedstocks and energy conversion technologies including corn and cellulosic ethanol, and four different vehicle classes: small- and mid-size cars and small and full-size SUVs. Co-product credits in EBAMM favor the ethanol pathway by accounting for ethanol co-products but not potential bioelectricity coproducts including steam for heat and fly-ash for cement, noted the researchers in their paper.

The net transportation output per hectare is larger for the bioelectricity case. With BEVs and ICVs of similar size, one can travel farther on biomass grown on a hectare of land when it is converted to electricity than when it is converted to ethanol...For this case, the gross transportation output per hectare is 85% greater for bioelectricity than cellulosic ethanol. This is largely due to fact that the small SUV BEV has an electric motor that is 3.1 times as efficient as the internal combustion engine of the small SUV ICV for highway driving.

—Campbell et al. (2009)

Among the other findings:

  • For the gross transportation distance, the bioelectricity output is on average 112% greater than the ethanol output for the full range of feedstocks, energy conversions, and vehicle efficiencies.

  • For the net transportation distance, several of the corn ethanol cases result in negative distances because the distance that could be traveled with the net fuel cycle inputs (petroleum via ICV and electricity, coal and natural gas via BEV) is greater than the distance that could be traveled with the gross ethanol output.

  • The average net transportation distance for the switchgrass feedstock was 81% larger (SE = 21%) for bioelectricity than ethanol.

  • While bioelectricity generally performed better than ethanol, the bioelectricity and ethanol pathways had similar results for highway driving with the small car and full-size SUV. The two BEVs tested by the EPA for these vehicle classes had particularly low highway efficiencies and low ranges (<166 km). This suggests that these specific BEVs were not designed for highway driving, as opposed to the midsize car BEV and small SUV BEV which perform well for city and highway driving.

While the relative efficiency of these pathways may be altered in the future with new powertrain technologies, heating co-products, and electricity storage approaches, the researchers said, based on the efficiencies of deployed bioelectricity technologies and emerging cellulosic ethanol technologies, the bioelectricity pathway consistently produces more transportation kilometers than the ethanol pathway.

In terms of greenhouse gas emissions, they found that the average net offset for bioelectricity generated from switchgrass is 108% greater (SE = 28%) than the offset for switchgrass ethanol. For both pathways, these GHG offsets could only be achieved if land use impacts are avoided. GHG offsets for bioelectricity could be greatly increased by accounting for the steam co-products during electricity generation. Applying carbon capture and sequestration (CCS) technologies with bioelectricity could result in a carbon-negative energy source.

These results provide further support for general bioelectricity applications which are already thought to have greater climate mitigation benefits than ethanol. Electric transportation may also provide a bridge that connects transportation to future renewable energy sources such as solar and wind power....On the other hand, electric transportation also provides a bridge to the use of conventional coal energy for transportation. These results do not indicate that bioelectricity is the preferred pathway over ethanol as there are numerous other criteria that need to be evaluated such as impacts on regional water resources, battery toxicity and recycling, air pollution, and economic constraints.

The optimal pathway for biomass will also depend on how efficiently other feedstocks can be converted to both liquid fuels and electricity. Specifically, the competitiveness of biomass ethanol depends on the cost of petroleum, whereas the competitiveness of biomass electricity depends on the cost of coal, wind, hydro, solar, and nuclear. These results do suggest, however, that alternative bioenergy pathways have large differences in how efficiently they use the limited available land to maximize transportation and climate benefits.

—Campbell et al. (2009)

Resources

  • J. E. Campbell, D. B. Lobell, C. B. Field (2009) Greater Transportation Energy and GHG Offsets from Bioelectricity Than Ethanol. Science doi: 10.1126/science.1168885

Comments

Darius

A have the same opinion. It is more rational to combust befoul on spot and produce el., sell it to the EV via grid and possibly use heat (cogeneration mode) than transport biomas and then use expensive transformation process and then ones again transport, blend it and finally spend resources on distribution.

jcwinnie

Now if the Congress critters were serving constituents they would respect such science.

Such a transition in the agriculture sector is doable, yet not easy. Still such a transition is a heck of lot easier now, when there still are resources, rather than after a Peak Oil crash.

And, speaking of respect for such findings, would that apply to the DoE / USDA partnership that espouses such improvement?

Aussie

Seems everybody thinks it is a great idea.

I'd like to see them drive for 5 hours on a tank of bioelectricity.

Scott

In my view there are benefits to both. Why put all of your eggs in one basket?

EVs are good for the city commute and short journeys, as they are more likely to be suitable in smaller cars for lower speeds.

Most of my short journeys are done by walking or taking the Metro, so I'd prefer personally for an algae led 'drop-in' biofuels approach which would suit me for when I need my car for longer road-trips. The technology is there, barriers are being broken, so it won't be long before we can fill our existing cars with gasoline which increasingly comes from bio-crude derived from algae.

Darius

Aussie,

I support ICE range extension option (cheep as possible). That would solve you problem and you can use conventional grain ethanol once per month since on average automobile covers only 40 miles per day.

HarveyD

Darius:

I agree with you. PHEVs will be the practical solution for many of us for the next 10 to 20 years, or until such time as higher performance e-storage units become available at a much lower cost.

However, as storage units improve, PHEVs will use more and more electricity and much less fuel. By 2020+, pure BEVs will replace pure ICE vehicles and most PHEVs. Heavy long range trucks may be the exception but e-trains could do a much better job. Cargo could be moved at each end with e-trucks.

Of course, very high speed e-passenger trains could replace all long range buses. e-city buses should be around soon.

Electricty can be produce 10 different ways. Biogas, Sun, Wind, Waves, Geothermal, Hydro and Nuclear are all known technologies. At power mix will be used and does not have to include coal nor Oil. NG will be used to the last drop.

Lets see what the post-lithium era will bring as e-energy storage. We could see a 10-fold increase in performance with a 10-fold decrease in price by 2030.

SJC

The fact remains that not everyone is going to scap their car and buy an EV tomorrow. If we wanted to make 100 million vehicles with 20 kwh of lithium batteries in the next 5 years, we probably could not. We will need cellulose biofuels ASAP to get off corn and reduce imported oil.

bot_feeder


It seems to me this research is on the wrong track.

I believe there is a substantial consensus that barring some breakthrough allowing solar energy to be converted to hydrocarbons at a far greater efficiency than you can get from photosynthesis, biofuels will only be able to provide a fraction of the energy we have previously obtained from fossil fuels.

Thus, biofuels will need to be devoted to uses where hydrocarbons are irreplaceable- chemicals for example. And, things like aircraft fuel, barring someone coming up with a revolutionary new way to run an aircraft.

As an energy source, the primary virtues of biofuels are its storeability and its energy density. You wipe out those benefits when you convert it to electricity.

Yes, we should run cars on electricity rather than hydrocarbons, but the electricity should not be produced from biofuels, it should come from wind or solar or nuclear or whatever.

Hydrocarbons will be a far more rare and expensive resource in the future than electricity. Consequently it will make no sense to convert hydrocarbons to electricity.

ai_vin

"Study Finds Bioelectricity Better Option Than Liquid Biofuels for Transportation Output and GHG Emissions"

Well big 'duh' Talk about studying the obvious.

"As an energy source, the primary virtues of biofuels are its storeability and its energy density. You wipe out those benefits when you convert it to electricity."

On the contrary; The primary virtue of biofuels [its storeability] also makes it an essential part of renewable electricity production. One of the often stated problems with wind/solar energy is that the supply doesn't follow demand. Biofuel's ability to produce electricity on demand corrects this problem.

Please watch this- http://www.youtube.com/watch?v=aNZgjEDPe24
They actually tried this and for several months their Combined Renewable Energy Power Plant matched supply to demand minute-by-minute.

"The secure and constant provision of power anywhere and at anytime by renewable energies is now made possible thanks to the Combined Power Plant. The Combined Power Plant links and controls 36 wind, solar, biomass and hydropower installations spread throughout Germany. It is just as reliable and powerful as a conventional large-scale power station.

The Combined Renewable Energy Power Plant shows how, through joint control of small and decentralised plants, it is possible to provide reliable electricity in accordance with needs. The Combined Power Plant optimally combines the advantages of various renewable energy sources. Wind turbines and solar modules help generate electricity in accordance with how much wind and sun is available. Biogas and hydropower are used to make up the difference: they are converted into electricity as needed in order to balance out short-term fluctuations, or are temporarily stored. Technically, there is nothing preventing us from 100 per cent provision with renewables."

Will S

bot_feeder said,

"Yes, we should run cars on electricity rather than hydrocarbons, but the electricity should not be produced from biofuels, it should come from wind or solar or nuclear or whatever."

Good point.

SJC

If you run a biofueled combined cycle power plant on syngas, you could get quite a bit out of every ton of biomass. Converting syngas to methanol or other fuels takes energy. Then you have the fact that the ICE is not that efficient compared with transmission lines, chargers, batteries, controllers and motors.

SVW

There is a third parameter that a deeply indebted nation should consider. How much needs to be invested?
An EV needs around 40kwhr of battery storage.
At $500 / kwhr this is $20,000 / vehicle.
So $20 billion / million autos.
But second generation biofuel plants (BTL) not cheap. Estimates vary but say $4/gal/yr for BTL facilities. Driving 20,000 miles per year at 25 mpg means = 800 gallons per vehicle per year which means $3200 of BTL plant per vehicle. So $3.2 billion per million vehicles. If you invest an extra $2000 per vehicle in a hybrid you will greatly increase mileage and decrease BTL plants needed.
At some point US needs to consider $ invested /ton carbon saved.

DaveD

@SVW

We should consider another alternative as well. If we only put 10kWh in each pack and make it a range extended hybrid with about a 40 mile all-electric range, then the price drops to "only" $5billion/million autos. Yet this would cover ~80% of all daily commutes so it would make a huge dent in our oil consumption.

That $5B per million autos is still a lot, but compare it to the $700Billion we ship out of this country every year for foreign oil.

By they way folks, contrary to popular belief most of our oil now comes from Canada and Mexico so it's not as much "terrorist funding" as we all fear. However, both are dropping in their oil production rapidly and within in 3-5 years they could both be net oil importers! Then we REALLY have a problem... wait till you see what happens when we're really dependent on the Saudi's, Iran, Russia and Venezuela!

We better get off our butts and do something people.

SJC

The people that can use EVs should, that takes them off oil completely. There are 55+ communities all over the country with people that do not even drive 4000 miles per year. If 10% of the drivers drove EVs that would be about a 5% reduction in imported oil. A good start...

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