Potential land competition between open-pond microalgae production and terrestrial dedicated feedstock supply systems in the U.S.

To date, feedstock resource assessments have evaluated cellulosic and algal feedstocks independently, without consideration of demands for, and resource allocation to, each other. We assess potential land competition between algal and terrestrial feedstocks in the United States, and evaluate a scenario in which 41.5 × 10⁹ L yr^-1 of second-generation biofuels are produced on pastureland, the most likely land base where both feedstock types may be deployed. Under this scenario, open-pond microalgae production is projected to use 1.2 × 10⁶ ha of private pastureland, while terrestrial biomass feedstocks would use 14.0 × 10⁶ ha of private pastureland. A spatial meta-analysis indicates that potential competition for land under this scenario would be concentrated in 110 counties, containing 1.0 and 1.7 × 10⁶ ha of algal and terrestrial dedicated feedstock production, respectively. A land competition index applied to these 110 counties suggests that 38 to 59 counties could experience competition for upwards of 40% of a county's pastureland, representing 2%-5% of total pastureland in the U.S.; therefore suggesting little overall competition between algae production, terrestrial energy feedstocks and alternative uses for existing agricultural production such as livestock grazing.