Life‐cycle assessment of local feedstock supply scenarios to compare candidate biomass sources

Abstract

The use of life cycle assessment (LCA) as a comprehensive tool to assess environmental impacts of bioenergies is recommended. Nevertheless, several methodological points remain under debate, particularly regarding the feedstock production step, which is a key stage of bioenergy chains. The present work focuses on field emissions during feedstock production, improving assessment methods by the use of process-based models. To do so, a real bioenergy chain, the local feedstock supply for a boiler located in northern France, was studied. The LCA compares flax shives, (the reference) with four other biomass sources: Miscanthus, cereal straw, linseed straw, and triticale as a whole plant. Six feedstock supply scenarios were also compared. The study aimed to test a new LCA methodology for agricultural chains by integrating local characteristics (such as climate, soil, and crop management data) and using models to estimate field dynamics of pesticide emissions and soil organic carbon (SOC). Results showed that flax shives and linseed straw had the lowest impacts, except for global warming: as a consequence, supply scenarios with the largest share of flax shives had the lowest impacts. For all selected impact categories, transportation and fertilization were the main contributors. SOC dynamics led to high C sequestration level (e.g. with Miscanthus) or to high CO 2 emissions level (e.g. with flax shives), thus significantly influencing the global warming impact. Sensitivity analysis showed a large influence of allocation method (economic or mass-based). This study demonstrated the relevance of integrating simulation models using local data in agricultural LCAs, especially for dynamics of SOC and pesticide from fields. Moreover, this work brought scientific elements to support the choice of flax shives as the main biomass feedstock, and the ranking of the other sources as alternative biomass supplies for the boiler.

Novel Miscanthus Germplasm-Based Value Chains: A Life Cycle Assessment

“…This is due to the related environmental and social problems, which are of high interest to society in general. Climate change, for example, is presently one of the most urgent environmental problems and, as a result, this impact category is included in virtually every study which assesses the environmental performance of miscanthus-based value chains (Godard et al, 2013; Parajuli et al, 2015; Roy et al, 2015). The ALO can be a problem if the utilization of land for biomass production leads to land-use competition and thus hinders the production of food crops.…”

Are the environmental benefits of Miscanthus × giganteus suggested by early studies of this crop supported by the broader and longer‐term contemporary studies?

“…Godard et al . (), wrote, ‘ Miscanthus was a net GHG sink due to high soil‐C sequestration rates …’ providing a ‘…negative global‐warming impact…’ in a study that compared the LCA of flax shives, M. × giganteus , cereal straw, linseed straw, and triticale used for boiler combustion. Similar to Wang et al .…”

“…This was less than fuel oil (6.14£ GJ −1 ) and was more expensive than gas (2.81£ GJ −1 ) and coal (2.05£ GJ −1 ) (Wang et al ., ). The cost of M. × giganteus could become more competitive with increased yields(Wang et al ., ) and shorter transport distances (Wang et al ., ; Godard et al ., ). Miscanthus also produced fewer GHG emissions than oil (Wang et al ., ).…”

Environmental aspects of fiber crops cultivation and use

“…Thus, agricultural production stage could be responsible to variations in GHG balances as fertilization and crop yields could vary over space and time, depending, among other factors, on climate, soil characteristics and land use (Godard et al, 2013). In the study of González-García et al (2010a) the hemp cultivation is significantly more detrimental than flax due to the higher amount of N fertilizer inputs, which contribute largely to the global warming (70% of total GWP, in the case of hemp, 30% of total GWP, in the case of flax).…”