Impact of integrated landscapes on bioenergy supply-shed sustainability and feedstock economics

Long term success of the lignocellulosic bioenergy industry depends on economically and environmentally sustainable feedstock production. Pioneer facilities utilizing crop residues must respect soil health when sourcing feedstock, limiting the location and quantity of biomass available for collection. Feedstock supply areas can become quite large when residue harvest rates are reduced to protect soil resources, challenging the economic sustainability of the system. By integrating dedicated energy crops into the production matrix of agricultural landscapes on a subfield scale, both the environmental and economic concerns of feedstock production can be eased. This work utilizes the Landscape Environmental Assessment Framework (LEAF) to model the environmental impacts of traditional corn (Zea mays L.) stover collection and landscape integration with switchgrass (Panicum virgatum L.) on a multi-county supply-shed in Central Iowa. Landscape design is based on the ability of switchgrass to economically outcompete row crops on existing low-productivity areas within a given field. Energy crop production on these marginal sub-field areas represents a financial loss-mitigation strategy with added benefits to soil health and surface water quality. Depending on the market price for herbaceous biomass and production costs for switchgrass, landscape integration has the potential to nearly double feedstock availability while improving supply system economics due to a decreased supply area and more efficient production system.