What’s more, models that show biomass supplying a significant amount of the nation’s transportation fuels tend to lean heavily on projections that vehicles will use half as much fuel as they do today, or even less. Without this increase in efficiency, however, there’s not enough land to provide a supply of biomass sufficient to put a dent in the demand for foreign oil.
“High vehicle efficiency is an essential factor for all sustainable transportation scenarios,” says Lee Lynd, engineering and biology professor at Dartmouth and co-author of the NRDC study that said biomass could replace gasoline by 2050. His model assumes two and a half times the current fuel economy for vehicles, as well as sophisticated crop rotations and other land-use decisions to make it possible to supply both food and energy from existing agricultural and pasture lands.
If the past is a guide, such models are extremely optimistic. In fact, although technology has improved fuel efficiency, the average number of miles per gallon for vehicles today is actually less than it was in the late 1980s, according to a recent EPA report. While engines have become better at extracting energy from fuel, cars have also become faster and heavier, cancelling any gains.
Lynd’s optimistic scenario also assumes that the conversion of stalks to ethanol can be done much more efficiently than it is today, by combining existing metabolic pathways from organisms such as fungi and bacteria. A recent white paper from a group of biomass researchers at MIT says that existing pathways will also need to be fine tuned to provide adequate yields. Creating these pathways will depend on continued research, even as less-efficient technologies begin to come online.
Experts look at biomass and see the potential to significantly improve our energy security while helping the environment. Certainly, the vision of vast fields of switchgrass and other crops replacing troubled oil fields in the Middle East is an attractive one. But turning biomass into more than a fuel for niche applications will require a strong R&D effort to bring the technology to fruition.
Image on home page (switchgrass) courtesy of Department of Energy