Sodbusting underway in South Dakota. (Photo by Boyd Schulz)
The government’s new renewable energy standards call for a big boost in biofuels, like ethanol, to replace some of the gas we burn in our cars and trucks. But a new study in a recent issue of Science magazine says not all biofuels are created equal. If they’re grown on land that’s converted from natural prairie or forest, they could make global warming worse. Stephanie Hemphill reports:
Transcript
The government’s new renewable energy standards call for a big boost in biofuels like ethanol, to replace some of the gas we burn in
our cars and trucks. But a new study in a recent issue of
Science magazine says not all biofuels are created equal. If
they’re grown on land that’s converted from natural prairie or forest,
they could make global warming worse. Stephanie Hemphill reports:
There’s a lot of buzz about biofuels. American farmers are planting
lots of corn, to be turned into ethanol. In Brazil, they make ethanol
from sugar cane, and they’ve replaced nearly a third of their gasoline
with it. In Malaysia and Indonesia, huge plantations grow palm oil for
bio-diesel.
But there’s a cost to these crops.
“In the top chunk of soil, we lose 40% of the carbon from that soil
when we convert it to agriculture.”
Joe Fargione says there’s almost three times as much carbon in
plants and soil as there is in the air. So when the soil is disturbed, it
releases carbon. When rain forests are cut to plant sugar cane, it
releases carbon. When peatlands are drained to plant palm trees, it
releases carbon.
Fargione is a biologist. He did the study for the University of
Minnesota and The Nature Conservancy.
According to his calculations, clearing land to plant crops releases
more carbon than we save when we burn biofuels instead of gas.
“It’s like taking out a loan and then trying to save money, but you
can’t save any money until you’ve paid off your debt. And the debts
are so large it’ll take decades or centuries for us to pay off that debt.”
We’ve released so much carbon into the air, it’ll take years to capture
it again.
Midwestern farmers are plowing land that was once set aside for
wildlife, to plant corn for ethanol. Fargione says that racks up a
carbon debt that’ll take about 90 years to repay. And cutting down a
rainforest takes even longer to recapture the carbon.
Farmers operate in a global market. So what Midwestern farmers do
can affect the Amazon.
Farmers usually alternate each year between corn and soybeans.
But now some are planting corn every year to meet the growing
demand for corn ethanol. Fargione says that’s prompting farmers in
Brazil to clear more land for soybeans.
“We can’t ask the world’s farmers to feed six billion people and then
say ‘also produce energy,’ without them requiring more land. That
land has to come from somewhere.”
But we don’t have to eliminate biofuels from the scene altogether.
Fargione says waste products from agriculture and forestry can be
turned into fuel. They don’t contribute to global warming. And
farmers could plant perennial grasses like switchgrass, where they
don’t have to plow the field every year.
“We can take land that’s been degraded, plant it to perennials, there’s
carbon storage in the soil, and then we can harvest those perennials,
and use those for biomass, and that could have a real benefit.”
He says we need policies that will make it profitable for farmers to
grow these better biofuel stocks.
Nathaniel Greene is a policy analyst at the Natural Resources
Defense Council. He says the research shows the need to develop
biofuels that really can address climate change.
“We can do biofuels smart, or we can do them stupid, and we have to
really choose.”
Congress has noticed. The new federal energy bill actually does start
encouraging these better biofuels.
The law tells the Environmental Protection Agency to figure out the
real global warming impact of the different biofuels.
For The Environment Report, I’m Stephanie Hemphill.