|May 10, 2009|
Bioelectricity, not biofuels, will get your car farther
|Content from: Philip Stavrou, CTV.ca News - A new study suggests vehicles using bioelectricity are far more efficient and better for the environment than ones using biofuels such as ethanol. Biomass, plant matter that’s grown and used to generate energy, is used to create both biofuels and bioelectricity. |
Researchers, in a study published in the journal Science, found currently available electric vehicles delivered more miles of transportation per acre of crops than ones that used biofuels.
"You get more transportation services by about 80 per cent if you go the electricity route than if you go the ethanol route," co-author Chris Field, director of the Department of Global Ecology at the Carnegie Institution, told CTV.ca from Washington. "The savings in greenhouse gas emissions were even larger -- about 100 per cent across the whole set of vehicles."
For example, a small SUV powered by bioelectricity could travel nearly 22,530 highway kilometres on the net energy produced from an acre of switchgrass. A comparable vehicle powered by biofuels could only travel about 14,480 on the highway.
Still, Field is quick to admit that there are hurdles facing both biofuel and bioelectricity production. "It’s not obvious that the technology hurdles are greater for one versus the other," Field said.
"Given the fact that there are these big technology hurdles we think it’s appropriate to put investment in working hard to develop... both sectors, recognizing that at least at this point it looks like the efficiency is much better on the electric approach."
Co-author Elliott Campbell, an assistant professor at the University of California, Merced, said one of the hurdles for electric cars is that they need better batteries. "For the ethanol pathway we need better conversion technologies... that allow us to make cellulosic ethanol at a cost-effective way on a commercial scale," Campbell told CTV.ca in an interview from California.
Campbell also said the land available to grow biomass crops is limited. If deforestation occurs to produce biomass crops, "you don’t get a greenhouse gas offset, instead you get an increase in the amount of greenhouse gases in that atmosphere," he said.
The study only looked at transportation and climate.
Campbell said researchers still need to look at water consumption, air pollution, and the economic costs of producing the alternative sources of energy. For now, it appears that officials are more focused on biofuels.
"Studies like ours could be used to ensure that the alternative energy pathways we chose will provide the most transportation energy and the least climate change impacts."
Additional Reserch 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.
"We found that converting biomass to electricity rather than ethanol makes the most sense for two policy-relevant issues, transportation and climate."
- Elliott Campbell