The Unites States Department of Agriculture’s (USDA) Agricultural Research Service (ARS) has released the results of a cost-benefit analysis for using switchgrass to heat homes and business in the northeast region of the U.S. The life-cycle assessment compared the costs of energy generation from coal, natural gas, fuel oil and switchgrass. The switchgrass is formed into pellets, cubes and round briquettes and then used for heating purposes.
Agronomist Paul Adler led the study along with ARS technician Fred McNeal, Pennsylvania State University grad student Tom Wilson and his advisor David Abler, and Drexel University assistant professor Sabrina Spatari.
“There have been a lot of studies on bioenergy potential,” says Adler. “Most of them are focusing on transportation, but we still need a viable, commercial, biobased fuel substitute for petroleum. In the meantime, our studies suggest that we already have opportunities to use homegrown feedstocks for producing heat, and that we can save money, reduce petroleum use, and cut greenhouse gas production in the process.”
The assessment calculated the costs associated with the production of switchgrass through the whole supply chain and the amounts of greenhouse gases emitted during the production, densification, and conversion to heat and power. The researchers obtained the necessary information from a Pennsylvania producer of the pellets.
According to the news release on the ARS website, the results found that “192 pounds of “carbon dioxide equivalent” (CO2e) were emitted for every ton of switchgrass dry matter that was grown, harvested, and delivered to densification plants for processing into pellets. CO2e is a measurement used to compare the emissions from various greenhouse gases based on their global-warming potential.”
When compared to other heating sources, “the researchers calculated that using switchgrass pellets instead of petroleum fuel oil to generate one gigajoule of heat in residences would reduce greenhouse gas emissions by 146 pounds of CO2e. Using switchgrass pellets instead of natural gas to produce one gigajoule of heat in residences would reduce greenhouse gas emissions by 158 pounds of CO2e.”
Additionally, the team found that it would cost $21.36 to produce each gigajoule of heat using switchgrass pellets while using fuel oil would cost $28.22 for one gigajoule of heat. When compared to coal, switchgrass dramatically reduces greenhouse gas emissions; however the cost is significantly less for coal.
The researchers estimate that by year 2022, the U.S. would have enough sustainably harvested biomass available to produce the pellets to offset the entire demand for heating oil in the northeast U.S. This would save consumers between $2.3 and $2.9 billion a year in fuel costs and reduce greenhouse gas emission in the northeast by 5%.
Adler says that “if we use the switchgrass to replace fuel oil instead of the coal used to generate electricity, we also substantially reduce greenhouse gas emissions at a much lower cost to consumers—and help meet our long-term goals for domestic energy production from alternative fuels.”