Which has lower greenhouse gas emissions: burning oil or substituting biofuels? It depends in part on what the land might be used for otherwise, but generally it’s the oil, according to an analysis (subscription needed) in the August 17 Science.
Various options for a 30-year period were analyzed. Biofuels can be supplied by land-inefficient methods: sugar cane, sugar beet, or corn to ethanol, for example. Cellulosic biofuels, not yet commercially competitive, use much less land because they use almost all of the plant above the soil. How do these methods compare?
Righelato and Spracklen compared avoided emissions for various crops (sugar cane, wheat, sugar beet, and maize to ethanol, and rapeseed and woody biomass to diesel), and effect of land-use choices on four biomes (tropical and temperate cropland and forest). Afforestration of the same land over 30 years sequesters much greater quantities of carbon, two to nine times as much. The exception was woody biomass in temperate zones, which had comparable benefits.
Whether we use oil or biofuels, improving fuel economy is a must, as is finding ways to get us out of cars and airplanes, experts on both sides of the issue agree.
I will post soon on cellulosic biofuels. If I see a response to this analysis, I’ll post it.
But all but the politicians and farmers agree that
ethanol from corn
and from
sugar cane
cannot reduce greenhouse gas emissions significantly in an environmentally friendly manner.
