Study: Switchgrass biofuel shows potential in fight against climate change

A man standing next to switchgrass (Warren Gretz, US Department of Energy)
A man standing next to switchgrass (Warren Gretz, US Department of Energy)

The grass is native to the US, non-edible and grows across North America. Fuel produced from the plant emits far less CO2 than gasoline.

Researchers from Colorado State University (CSU) in the US have studied switchgrass as an alternative biofuel feedstock to corn (corn often comes under fire for being resource intensive and competing with demands for food). The new fuel has a climate footprint ranging from -11 to 10 grams of CO2 per mega-joule, compared to gasoline’s 94 grams.

Instead of focusing on the support aspects of the biofuel supply chain like transport, the CSU study looks at where and how producers generate feedstock. The researchers concluded that these factors have as much or more influence on the carbon footprint of a biofuel.

John Field, a research scientist at the Natural Resource Ecology Lab at CSU, said: "What we saw with switchgrass is that you're actually storing carbon in the soil," he said. "You're building up organic matter and sequestering carbon."

Commenting on the plant’s impact on the environment and on farmers, Field said: "They don't require a lot of fertilizer or irrigation… Farmers don't have to plow up the field every year to plant new crops, and they're good for a decade or longer."

The team used a modelling tool called DayCent to track the carbon cycle, plant growth and how growth responds to factors like climate and weather at the local level. DayCent was developed by CSU in the mid-1990s to assess and predict how crop production helps or hinders efforts against climate change. It also looks at how viable certain crops are in an area.

Researchers chose to study a site in Kansas for the paper by virtue of it housing one of only three cellulosic biofuel production plants in the US.

"Biofuels have some capabilities that other renewable energy sources like wind and solar power just don't have," said Field. "If and when the price of oil gets higher, we'll see continued interest and research in biofuels, including the construction of new facilities."

The study is called ‘High resolution techno-ecological modelling of a bioenergy landscape to identify climate mitigation opportunities in cellulosic ethanol production’ and was published in Nature Energy 19 February.

A man standing next to switchgrass (Warren Gretz, US Department of Energy)