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Study: 'Jet-fuel' crop success hinges on sites, seeds

A two-year study in Brazil determines that seed quality and land conditions are key to maximizing the benefits of jatropha-curcas, whose olives yield oil for alternative jet fuel.

Robert Bailis Yale University

Boeing's two-year study of jatropha-curcas agriculture in Brazil has found that location choice and strong seeds are the key to maximizing the crop's benefits, the company said today.

The jatropha-curcas plant has been under close scrutiny in recent years by scientists and companies because its olives yield an oil that can be made into an alternative jet fuel. The weedy plant can grow in adverse soil conditions. And in addition to yielding oil, it provides, like most plants, the secondary benefit of removing carbon from the atmosphere. Many have been trying to compare the carbon footprint of producing petroleum-based jet fuel vs. producing jatropha-based jet fuel, which includes both the farming and processing.

Robert Bailis, an assistant professor, and Jennifer Baka, a doctoral student, of Yale University's School of Forestry and Environmental Studies led the research. They concentrated on the amount of greenhouse gas emissions that were reduced in a given area as a result of jatropha farming and fuel production. The also looked at the socioeconomic impact of producing the crop and its fuel.

Jennifer Baka Yale University

Theirs was a real-world study that collected data from jatropha farms and processing plants in Brazil, and included interviews with the farmers and processors. The farms ranged in size from 10 hectares to thousands of hectares.

"This analysis presents a comparison of life-cycle [greenhouse gas] emissions from synthetic paraffinic kerosene (SPK) produced as jet fuel substitute from jatropha curcas feedstock cultivated in Brazil against a reference scenario of conventional jet fuel," the report stated.

Bailis and Baka found that the type of land on which the jatropha plant grew had a direct correlation to its carbon footprint in comparison with petroleum-based jet fuel.

When planted on lands that were already fallow or degraded by use, the jatropha crop reduced greenhouse gas emissions by over 60 percent of the area's baseline levels when compared against production of petroleum-based jet fuel. However, in woodland areas that had been home to trees and shrubs and were cleared for the sole purpose of cultivating and processing jatropha, the emissions ratio actually increased.

Bailis and Baka also found that some farmers struggled due to poor resources.

"A second important finding is that early jatropha projects suffered from a lack of developed seed strains, which led to poor crop yields," the report said.

The results pointing to the importance of careful choice of land and seed may seem obvious. But this is one of the first studies conducted in Latin America that uses hard data and interviews, as opposed to estimates and computer modeling, and applies it to the sustainability criteria developed by the Roundtable on Sustainable Biofuels, according to Boeing.