Biomass yield potential on U.S. marginal land and its contribution to reach net-zero emission

Abstract

Bioenergy with carbon capture and geological storage (BECCS) is considered one of the top options for both offsetting CO₂ emissions and removing atmospheric CO₂. BECCS requires using limited land resources efficiently while ensuring minimal adverse impacts on the delicate food-energy-water nexus. Perennial C4 biomass crops are productive on marginal land under low-input conditions avoiding conflict with food and feed crops. The eastern half of the contiguous U.S. contains a large amount of marginal land, which is not economically viable for food production and liable to wind and water erosion under annual cultivation. However, this land is suitable for geological CO₂ storage and perennial crop growth. Given the climate variation across the region, three perennials are major contenders for planting. The yield potential and stability of Miscanthus, switchgrass, and energycane across the region were compared to select which would perform best under the recent (2000–2014) and future (2036–2050) climates. Miscanthus performed best in the Midwest, switchgrass in the Northeast and energycane in the Southeast. On average, Miscanthus yield decreased from present 19.1 t/ha to future 16.8 t/ha; switchgrass yield from 3.5 to 2.4 t/ha; and energycane yield increased from 14 to 15 t/ha. Future yield stability decreased in the region with higher predicted drought stress. Combined, these crops could produce 0.6–0.62 billion tonnes biomass per year for the present and future. Using the biomass for power generation with CCS would capture 703–726 million tonnes of atmospheric CO₂ per year, which would offset about 11% of current total U.S. emission. Further, this biomass approximates the net primary CO₂ productivity of two times the current baseline productivity of existing vegetation, suggesting a huge potential for BECCS. Beyond BECCS, C4 perennial grasses could also increase soil carbon and provide biomass for emerging industries developing replacements for non-renewable products including plastics and building materials.