Biofuels are getting a lot of attention as the world looks for alternatives to oil, but new research shows that biofuels carry a risk of increasing global warming and destroying biodiversity. “We know people want to do the right thing, but we want to make sure they have enough information to decide what that is,” says Elizabeth Gray, the Conservancy’s director of science in Washington.

Gray and her colleague, University of Washington professor Martha Groom, recently published a paper in the peer-reviewed journal Conservation Biology that examines the environmental footprint of various kinds of biofuels, and lays out principles for policies for environmentally sound biofuels.

The study qualitatively contrasts major potential sources of biofuels, including corn, grasses, fast-growing trees and oil crops, highlighting their relative impacts on the environment in terms of water and fertilizer use and other criteria to calculate the environmental footprint of each crop.

As well as comparing potential biofuel feedstocks, the study also recommends a number of major principles for governing the development of environmentally friendly biofuels.

Nature.org: What was the impetus for your paper?

Elizabeth Gray: Seattle is a very green city with a lot of environmentally minded people. A couple of years ago, there was a big push in the state to promote legislation supporting renewable energy, including the use of biofuels. At that point, many in the environmental community were supportive of biofuels as an alternative fuel to reduce greenhouse gas emissions. People wanted to do the right thing - but it seemed to me that we didn’t have the information to know what the “right” thing was. So I started delving into some of the literature to try and understand biofuels myself, as both a scientist and a citizen, and I discovered that a lot of critical information was missing.

Nature.org: What kind of information?

Elizabeth Gray: I couldn’t find answers to simple questions like, “What’s the environmental footprint of producing these biofuels?” and “What is the net reduction in greenhouse gas emissions when you consider the entire production life cycle of a given biofuel?” So I teamed up with a colleague, Dr. Martha Groom, and the two of us, along with one of her grad students, started to investigate the answers to those questions. We had three goals for our research:

*To urge others to consider the entire production life cycle when promoting biofuels as a means for reducing green house gas emissions.

*To provide policy recommendations to promote sustainably grown, biodiversity-friendly biofuels.

*To identify critical research questions that conservation biologists could address to help develop sustainable fuels.

So instead of trying to pass judgment on whether biofuels are good or bad, we operated under the assumption that biofuels are here to stay, at least in the short term. What people need, we believe, is access to information about biofuels that will allow them to make well-informed decisions about if and how biofuels can help reduce greenhouse gas emissions. Our hope is that when biofuels are produced and used, they are done so in the most environmentally friendly way possible, which includes making them not only climate friendly, but also biodiversity friendly.

Nature.org: Why was this “green” technology not tied to biodiversity from the start?

Elizabeth Gray: Up to this point, most decisions have been based on economic and political factors, not ecological factors.

Nature.org: Are there any biofuels myths that you’d care to debunk?

Elizabeth Gray: It turns out there’s a lot of conflicting information out there about biofuels, and this is mostly due to people comparing apples and oranges. The debate about whether a particular biofuel does or does not lead to a reduction in greenhouse gas emissions stems from different studies calculating a reduction in CO2 in different ways.

The majority of studies on biofuels only look at part of the puzzle, such as how much less CO2 is released when ethanol is burned versus regular gasoline. But you need to look at the entire production life cycle (grow, harvest, transport, refine, distribute, burn) to understand whether a particular biofuel leads to a net reduction in greenhouse gas emissions and to make meaningful comparisons across the board. We provide this information in the first table in our paper, and the truth is, not all biofuels are created equal.

Nature.org: How did you examine the lifecycle of the different biofuels?

Elizabeth Gray: To consider the entire lifecycle of each biofuel, we looked at the following factors: energy conversion efficiency, greenhouse gas emissions, water use, fertilizer use, pesticide use, energy inputs, fuel yield, and the amount of land area needed to meet 50 percent of U.S. transportation fuel demands.

Nature.org: What did you learn about the land area needed for different biofuels?

Elizabeth Gray: Land area is a critical consideration when determining the environmental footprint of a biofuel, because fuel stocks that require large areas to grow take this area away from food or wildlife. In fact, one of the three general principles we outline to guide development of biodiversity-friendly biofuel policies is to not convert native and essential food-crop habitats. The other two are to promote sustainable and low-impact fuel stocks and to require net carbon-neutral biofuels.

For corn, which makes up more than 90 percent of the biofuels we currently produce in the U.S., this idea about taking land away from food production turns out to be true. You would need more land than we have in the United States to meet that 50 percent demand; plus corn ethanol is inefficient and increases greenhouse gases, not decreases them, when you take the entire production lifecycle into account.

Obviously corn is not a feasible solution, but other biofuel technology like microalgae looks promising. Of the biofuels we investigated, it requires the least amount of land, has the highest fuel yield, and produces the least amount of greenhouse gases. Unfortunately like many of these new biofuel technologies, it is still undergoing a lot of R&D and is currently only produced at a small scale. Woody biomass is another option that is growing in popularity. We think this will work best when planting trees to restore degraded lands or by using debris from production forests. All these options have issues that we will need to stay on top of, but at least the initial assessments look good for reducing biodiversity impacts and creating a sustainable alternative to fossil fuels without converting any more lands, whether natural or agricultural.

Nature.org: What are the hurdles biofuels will have to overcome to make it big?

Elizabeth Gray: There are technological, political and public perception hurdles to overcome, but the biggest is economic. Even though we didn’t include an economic analysis in our study, biofuels will never become sustainable if they don’t appeal to the bottom line. One way to look at this is to consider the energy input to output ratios. Even though corn should fail using this logic, due to subsidies, so far it has not. We need to create capital markets and fund R&D efforts to make alternative energy sources that are more climate- and biodiversity-friendly a reality.

Nature.org: In terms of your ultimate policy recommendations what was your hope? Were you trying to give policy makers easier access to science or was it more about getting scientists involved in policy?

Elizabeth Gray: Well, we didn’t want to write this paper just for scientists; we also wanted decision makers to read the paper so they would incorporate our recommendations into policy. We lay out 12 straightforward recommendations for promoting sustainable biofuels that we think could be incorporated into any biofuel policy. However, science doesn’t always cross into policy easily.

The Nature Conservancy has just started a Biofuels Working Group, which includes science, policy and conservation experts to raise awareness and get information to policy makers. For example we’re currently looking into certification systems for sustainably produced biofuels. The group meets regularly, so we’re able to stay abreast and respond to the multitude of studies coming out almost daily.

So we’ve brought policy makers and scientists closer together, but scientists still have some important roles to play in the biofuels debate. First, we need to raise awareness of the important issues. Additionally, there is a need for scientists to devote research to some of these outstanding questions that will enable us to move towards more sustainable biofuels. Our paper outlines a number of research questions that still need to be answered, and our hope is that this paper will encourage scientists to pursue those questions.

Finally, I believe scientists have a responsibility to translate their findings so that they can be incorporated into concrete policy recommendations. This is, unfortunately, a step that is often missing in the way we conduct our research as scientists. However, making our findings clear, easy to understand, and possible to implement is crucial for shifts in the way science is incorporated into policy.

Nature.org: In addition to your policy recommendations, what were the main conclusions of your study?

Elizabeth Gray: Our study has three key messages:

One, we need a national biofuels policy that will specifically seek to minimize the risks to biodiversity and to our climate. This has implications for the types of fuel stocks we decide to produce and use. Each one has its own limitations that will require specific policies to govern its entire production life cycle, whether it is the way we thin forests for woody biofuels, or the way we identify areas that should and should not be converted for biofuel production. My hope is that those policies will take into account both biodiversity and climate as they are drafted.

Our second message is that we need a certification system that certifies both biodiversity-friendly and climate-friendly biofuels. There are many ways this could happen, whether it’s top down from the government or even bottom up from the industry itself, but our point is - this needs to happen.

Finally, we believe that if we’re serious about reducing greenhouse gas emissions, then we have to couple decreased energy demands with alternative energy production. By alternative energy production I mean using energy sources that either reduce greenhouse gas emissions or produce no emissions when you account for the entire production life cycle and ones that lead to no destruction of natural habitats. Biofuels will never be a silver bullet, but at least in the short term, given the right choices and policies, they can help.

Nature picture credits (left to right): Photo © Timothy Lindenbaum/TNC; Elizabeth Gray, Photo © TNC.