COLUMBUS, Ohio — A common farm weed may hold the answer to making jet fuel greener and cheaper to produce than other eco-friendly alternatives. A team from The Ohio State University says stinkweed takes less fertilizer and fewer pesticides than other plants scientists have been eyeing for renewable sources of jet fuel.
Stinkweed, which also goes by pennycress, is a winter annual plant which reproduces through the release of seeds. The new study finds, unlike other crops, growing the weed would take less soil tilling — reducing the environmental costs of producing it in bulk. Those costs include the release of carbon dioxide emissions which pollute the air and contribute to climate change.
“Reducing greenhouse gas emissions from air travel will mean not just incremental changes, but a fundamental change in how we have been producing fuel and where that fuel comes from,” says study senior author Ajay Shah, an associate professor of food, agricultural and biological engineering at Ohio State, in a university release. “And what we found is that pennycress might make a very good alternative fuel, especially when you consider the environmental costs of producing it.”
Stinkweed smells just right as a biofuel
Researchers used computer models to estimate the environmental impact of growing, transporting, and converting stinkweed into a fuel for airplanes. The team also calculated the climate impact of having to burn off leftover byproducts from refining stinkweed seeds.
These models revealed how much energy it would take to produce stinkweed jet fuel from these seeds. They also compared these energy costs to fellow biofuels such as soybean oil, canola, or sunflowers.
Results show it takes half as much energy to make jet fuel from stinkweed as it does from both canola or sunflowers. It takes just a third of the energy to make stinkweed jet fuel in comparison to soybean oil. The energy costs are about the same as making jet fuel from the flowering plant camelina.
Biofuels still cost more than traditional gases
Although stinkweed may be a better alternative for biofuel environmentally, study authors find it still costs more to produce from the financial standpoint. However, the team says knowing exactly what it would take to covert the crop into fuel makes it easier for farmers and policymakers to find ways of combating climate change.
“Pennycress also makes an appealing alternative jet fuel because of its growing season,” Shah says. “It is a winter cover crop that can be grown between corn season and soybean season, giving the same body of farmland an extra production cycle each year.”
“Pennycress can be planted when corn is still standing in the field, before the corn harvest,” the researcher adds. “And it can be harvested before the soybean crops are planted. The bottom line is it can be used as a cover crop, it doesn’t divert any agricultural production land, and it has suitable properties for renewable jet fuel production.”
The study, funded by the U.S. Department of Energy, also reveals that greenhouse gas emissions from air travel account for about two percent of all human-created carbon dioxide emissions.
“When it comes to pennycress, production and logistics are the big contributors to both the environmental impacts and the costs, and those are the challenge areas – they have to be streamlined and solved to make it more efficient,” Shah concludes. “If we could improve those areas, we could make production more energy-efficient and substantially lower the costs and environmental impacts.”
The study is published in the journal Applied Energy.