Measuring the environmental impact of bioenergy

When it comes to life-cycle analysis, Ming Xu and Shelie Miller, two assistant professors at SNRE, aren’t taking the easy way out. Life-cycle analysis (LCA), a tool used to assess the environmental impact of a product or process by following it from “cradle to grave,” is most readily applied to well-established industries with lots of available data, like food and automobiles. However, some of the most needed applications of LCA are evaluations of emerging systems. So Xu and Miller have decided to take on one of the most amorphous systems of all: U.S. bioenergy. They’ve received a three-year, $310,000 National Science Foundation grant for the task.

“It’s a messy system that has mostly non-point source emissions and dramatic natural fluctuations,” Miller said. “But these are the things that make bioenergy a fun problem to tackle.”

LCA for bioenergy must consider not just greenhouse-gas emissions but also the consequences of agriculture, including fertilizer runoff, erosion, and water and land use changes. The researchers will modify standard LCA frameworks to integrate agent-based modeling and geographic information system spatial analysis—methodological advances in LCA that accommodate new technologies and shifting supply chains.

Xu and Miller plan to apply their improved LCA model to switchgrass, a perennial North American prairie species that has gotten a lot of attention as a potential energy crop but is not currently cultivated as biofuel. Switchgrass is expected to be more environmentally favorable than energy crops such as corn, but its benefits depend largely on where it is planted and by whom—if uncultivated land is plowed to seed switchgrass, net consequences for the environment could be negative. This complexity makes switchgrass an ideal candidate for Xu and Miller’s integrative LCA framework.

The researchers think of their LCA model as a roadmap for reaching bioenergy development goals and meeting market demand while minimizing environmental impact.

Both assistant professors are part of the Sustainable Systems field of study within SNRE and affiliated faculty at the Center for Sustainable Systems. Their project’s formal title is “Developing a Spatially-Explicit Agent-Based Life Cycle Analysis Framework for Improving the Environmental Sustainability of Bioenergy Systems.”