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| Human World on Jan 26, 2012

Amelia Wolf: Is US Southwest a good place to grow biofuels?

Biofuel production in the southwestern U.S. can add to the country’s existing biofuels portfolio, according to a study by the U.S. Geological Survey.

EarthSky spoke with Researcher Amelia Wolf, an ecologist and post-doctoral fellow at the Carnegie Institution of Science in the Department of Global Ecology at Stanford University about growing biofuels in the U.S. Southwest.

Biofuel production in the dry southwestern United States might have potential to add to the country’s existing biofuels portfolio, according to a study conducted by the U.S. Geological Survey (USGS) and presented at the Auguest 2011 meeting of the Ecological Society of America, in Austin, Texas.

The study looked broadly at the potential of growing crops for biofuels in five southwestern U.S. states: California, Nevada, Utah, New Mexico, and Arizona. Those crops include “first-generation” biofuel feedstocks – food crops such as corn, soy and sugarcane. And they include the “next-generation” biofuel feedstocks of switchgrass and algae.

The U.S. Renewable Fuel Standard, part of the Energy Policy Act of 2005, sets a goal for biofuel use in the U.S. by 2022. It suggests that 20 percent of the nation’s estimated fuel use in 2022 – about 36 billion gallons – can be from biofuels. Researchers with the study reported that although 25 percent of corn grown in the U.S. is currently used for biofuels, corn-based ethanol only accounts for about 1.3 percent of U.S. fuel. They say switchgrass has the potential to yield about 790 million gallons, or two percent of the 2022 renewable fuel standard. The upper limits for growing fuel from algae were found to be about 5.3 billion gallons, or 14 percent of the 2022 renewable fuel standard.

Switchgrass might be harvested for biofuels in the U.S. Southwest.

Switchgrass might be grown and harvested for biofuels in the U.S. Southwest.

Researcher Amelia Wolf, an ecologist and post-doctoral fellow at the Carnegie Institution of Science in the Department of Global Ecology at Stanford University, told EarthSky:

The most important thing to think about when considering the future of biofuels is that there are tradeoffs with growing biofuels in any part of the country.

And in the Southwest, especially, there are tradeoffs with water use. There is a lot of potential land availability, but there are also potential overuses of water. And one of the great things in the Southwest is that the infrastructure is just getting developed. And so we have a chance here, a real opportunity to approach this at the beginning and think about how best to proceed and really be able to say, this is going to be the equation when we think about water use.

And this is where the potentials are. This is the uppermost production possibility.

Also, there’s unique habitat in the Southwest. So there are ecological issues to think about. Algae doesn’t take up a lot of land space, so that’s a positive. But this is going to involve basically paving over some areas. Photobioreactors are kind of a factory. And so what the unique biological resources of the land are need to be considered. A lot of tradeoffs need to be thought about. It’s a great time to start doing that as all this technology is being developed.

A photobioreactor, used to grow algae to make biodiesel. Image Credit: Jurveston

A photobioreactor, used to grow algae to make biodiesel. Image Credit: Jurveston

Dr. Wolf explained why the southwestern U.S. is being looked at as a place to grow biofuels.

There are some really big potential benefits of using land in the U.S. Southwest. There’s a lot of public land, first of all. And there’s a lot of available land that might be able to be used. There’s high incoming sunlight in the U.S. Southwest – that’s obviously is a requirement of growing plants. And there’s very little food production that goes on there. So competition for food would be very low. But there’s not a lot of water.

So what we wanted to do is look at what the potential for biofuels production would be without increasing the pressure for water use in the Southwest. That really takes out of contention a lot of what we call first-generation biofuels. These are biofuels produced from corn, soy, and sugarcane. It makes the southwestern U.S. a possible candidate for these next generation biofuels that are really in the exciting research and development stage.

A cotton farm in Arizona. Future site for biofuels?

A cotton farm in Arizona. Future site for biofuels?

Farmers could switch from growing hay to growing switchgrass, which could be collected and turned into cellulosic ethanol, said Wolf.

About 75 percent of water use in the Southwest is actually used for agriculture, which surprised me when I first learned that. And a good chunk of that goes to producing hay. And so there’ve been some analyses that if we really start moving to being able to create cellulosic biofuels, switchgrass fields might start replacing hay.

The story, said Dr. Wolf, is a little different when considering algae and its potential as a biofuel.

Algae is in an earlier stage of research and development. They can be grown either in open ponds or in closed systems. These are called photobioreactors. They have some real advantages in that, per area land, a lot of fuel can be produced from these photobioreactors. Where production is relatively low per acre of land with the traditional crop, putting algae on an acre of land produces a lot more biofuel. So that leads to a lot less land conversion.

But it’s also very energy-intensive – it’s kind of like putting up a factory. And so one of the things you can do to reduce the footprint of putting these things on land is to put these algae photobioreactors next to either a wastewater treatment facility or a CO2 source, such as a power plant. People might have heard of flue gas that comes off of a power plant. That’s mostly CO2. And in order to grow plants, you need both CO2 as well as water and nutrients, which you can get from wastewater.

The researchers in the study include Amelia Wolf and Sasha C. Reed of the U.S. Geological Survey in Moab, Utah.

This video features researcher Jonathan Trent of NASA Ames Research Center describing algae-growing experiments.

Bottom Line: Biofuel production in the southwestern United States could help meet the nation’s future goals for renewable fuels, according to a study done by the U.S. Geological Survey. EarthSky spoke to Amelia Wolf of the Carnegie Institution of Science in the Department of Global Ecology at Stanford University, one of the researchers, who was in Austin, Texas for the 96th annual meeting of the Ecological Society of America, held August 6-12, 2011.