When it comes to biofuels, look at big picture
Biofuels are the hot topic. Make fuel from the things we usually consider waste, and then we can drive our SUVs with some peace of mind knowing the source of energy is renewable. Save on fossil fuels and reduce pollution emissions.
That just seems like the classic win-win situation. However, some of the most popular current biofuel stocks might have exactly the opposite impacts than intended, according to a study by a biologist at the University of Washington, Bothell. The study looked at factors such as the energy needed to produce a renewable fuel source compared with the amount of energy produced, the impact on soil fertility, and effects on food supply when fuels based on crops such as corn and soybeans mix with fossil fuels. Based on those factors, the authors determined that corn-based ethanol is the worst alternative overall.
"It's foolish to say we should be developing a particular biofuel when that could mean that we're just replacing one problem with another," said lead author Martha Groom of the UW Bothell.
Precise calculations should determine the ecological footprints of large-scale cultivation of various crops used for biofuels. Because corn requires such large amounts of energy to grow and then convert to ethanol, the net energy gain of the resulting fuel is modest. Using a crop such as switchgrass, common forage for cattle, would require much less energy to produce the fuel, and using algae would require even less. Changing direction to biofuels based on switchgrass or algae would require significant policy changes, since the technologies to produce such fuels are ready yet.
The paper's policy suggestions are "not definitive at all," Groom said, "but rather each category calls out a question and is a starting point in trying to find the proper answers."
These concerns are becoming more acute with the rapid rise of food and fuel prices, she said. The issue is especially touchy for farmers, who for the first time might be realizing significant profits on their crops, but it also is a serious concern for motorists.
"I've heard about people getting their gas tanks siphoned, and I hadn't heard of that since the '70s," she said.
A difficulty, Groom said, is while escalating prices add pressure to find less costly fuel sources, acting too hastily could create a host of other problems. For example, farmers who plant only corn because it is suddenly profitable and do not rotate with crops such as soybeans, are likely to deplete their soil, which could limit crop growth and promote soil erosion.
Furthermore, some plants are better than other plants for absorbing carbon dioxide from the atmosphere, while others perhaps need more cultivation, which requires more fossil fuels for farm equipment. In addition, fertilization, watering, and harvesting all require energy.
"We don't want to make new mistakes. If we don't ask the right questions to start with, we're going to replace old problems with new ones," she said.
The following are policy recommendations:
- Calculate a biofuel's ecological footprint
- Promote only sustainable biofuels
- Select highly efficient species for biofuels
- Work to minimize land needed for biofuels
- Encourage reclamation of degraded areas
- Prohibit clearing areas for more cultivation
- Promote use of energy crops that require less fertilizer, pesticide, and energy
- Promote native and perennial species
- Prohibit use of invasive species
- Promote crop rotation on cultivated lands
- Encourage soil conservation
- Promote only biofuels that are at least net carbon neutral
For related information, go to www.isa.org/manufacturing_automation.