A new study has determined that though biofuels are widely considered as a source of renewable energy, some of them might cause severe environmental impacts and reduce biodiversity unless principles and standards for production are developed and implemented.
The study, published in Conservation Biology, qualitatively contrasts major potential sources of biofuels, including corn, grasses, fast-growing trees and oil crops.
The study highlights their relative impacts on the environment in terms of water and fertilizer use and other criteria to calculate the environmental footprint of each crop.
Among its prime example is corn-based ethanol, which is currently the most widely used biofuel in the United States, but is also the most environmentally damaging among crop-based energy sources.
According to lead author Martha Groom of the University of Washington, "The central goals of any biofuel policy must minimize risks to biodiversity and to our climate."
She recommends the further use of algae and fast-growing trees as biofuel sources because they yield more fuel per acre than any feedstocks currently being pursued.
As well as comparing potential biofuel feedstocks, the study also recommends a number of major principles for governing the development of environmentally friendly biofuels.
Feedstocks should be grown according to sustainable and environmentally safe agricultural practices with minimal ecological footprints, which is the area of land required to grow and support sufficient amounts of the crop.
In particular, emphasis should be placed on biofuels that can sequester carbon or have a negative or zero carbon balance, according to the study.
"While some biofuels may be an improvement over traditional fuels, we believe we should focus much more on the biofuels of the future that can be developed in small spaces, rather than extensively on crop lands," explained Groom.
"We also must shun biofuels that are grown by clearing biologically-rich habitats, such as tropical rainforests, as has occurred with oil palm and some other biofuels," she added.