Optimizing GHG emission and energy-saving performance of miscanthus-based value chains

Abstract

Miscanthus is a high-yielding lignocellulosic crop providing up to 40 t of dry matter per hectare and year. Its biomass can be used in energetic or material utilization pathways. The goal of this study was the comparison of three different conversion techniques (combustion, second-generation bioethanol, and insulation material) for miscanthus biomass produced at five locations throughout Europe using a life cycle assessment approach. In particular, the interdependencies between the cropping location, the miscanthus genotypes, and the utilization pathways were investigated. The potential savings of greenhouse gas (GHG) emissions and fossil energy were analyzed through comparison with a corresponding substituted product system. The highest GHG savings of all scenarios investigated were achieved by heat and power production in Portugal (42.7 t CO2-eq ha−1 a−1). However, at the other four locations (Sweden, Denmark, Germany, England), bioethanol production gave the highest GHG savings. In contrast, the highest energy savings were achieved by combined heat and power generation via combustion at all five locations (up to 642 GJ ha−1 a−1). A high correlation was found between yield and both GHG-emission savings and energy savings. Biomass composition and quality showed a comparatively low impact on the results. However, the composition is assumed to have a high relevance for other impact categories not assessed within this study, such as acidification and eutrophication.