Scientists say electricity made from plant material, or biomass, is a more energy efficient and environmentally friendly way to power our automobiles than ethanol, a gasoline alternative that’s also made from biomass.

As public concerns increase over oil prices and global warming caused by the burning of fossil fuels, scientists have turned their attention to alternative energy sources created from plants.

So-called biomass technology is being hailed as way to make ethanol, a gasoline alternative to fuel combustion engines. But biomass is also attracting interest as a fuel for power plants to generate electricity that could then be used to charge the batteries for electric vehicles.

In a study published this week in the journal Science, researchers compared the energy efficiency of liquid ethanol made from corn and bioelectricity made from switchgrass, a wild, woody perennial, drought-resistant grass that can be grown in marginal or abandoned farmland.

Study co-author Elliott Campbell of the University of California in Merced says bioelectricity came out on top in a number of areas.

Campbell told a Science magazine interviewer that use of bioelectricity in transportation resulted in far fewer greenhouse emissions than internal combustion fuels.

Campbell added that cars powered by biomass generated-electricity drove 81 percent more kilometers per unit of land than cars fueled by corn-based ethanol.

“What we found is that if you burn this biomass to make electricity to power electric vehicles you can get a lot more transportation and a lot more greenhouse gas offsets than if you converted it to ethanol,” Campbell.

Scientists say electricity derived from switchgrass is the most efficient energy source they studied. They say it would take far less valuable farmland to produce energy from switchgrass than it would take to produce the same amount energy in the form of corn-based ethanol.

In the move toward biofuels to replace petroleum products, Campbell says cars powered with bioelectricity appear to be the way to go.

“If we’re going to anticipate that shift and think holistically about the best way to build up our bioenergy resources infrastructure, then we might want to start thinking about bioelectricity as a viable energy pathway,” said Campbell.

The authors of the study say they now need to consider other issues related to biomass energy conversion, such as water consumption, air pollution and the relative costs of converting biomass to ethanol or to electricity.