Priority of domestic biomass resources for energy: Importance of national environmental targets in a climate perspective

The optimal use of biomass from a global warming mitigation perspective depends upon numerous factors, including competition for land and other constraints. The goal of this study is identifying optimal uses of domestic biomass resources for the case of Denmark, with the objectives of minimizing global warming contribution and fossil energy resource consumption. For this purpose, consequential life cycle assessment of the different options for biomass was performed. Optimal solutions were identified, given specific national environmental targets, using linear programming. Results highlighted that utilizing the energy potential of manure and straw represents the primary opportunity for further global warming mitigation. For this purpose, co-digestion (for manure) and combustion with heat-and-power production (for straw) appear as the most promising technologies. The utilization of biomass (or biogas) for electricity/heat is generally preferred, as long as coal/oil is still used within the energy system. Yet, to fulfill environmental targets for renewable energy in the transport sector, the diversion of a significant share of biogas (and/or other biofuels) from these more beneficial uses is necessary. To completely phase out coal/oil, additional biomass (to current domestic resources) must be included, either through domestic energy crops cultivation or biomass/biofuel import; alternatively, natural gas could be used.