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Research article - Peer-reviewed, 2017

Climate impact assessment of willow energy from a landscape perspective: a Swedish case study

Hammar, Torun; Hansson, Per-Anders; Sundberg, Cecilia

Abstract

Locally produced bioenergy can decrease the dependency on imported fossil fuels in a region, while also being valuable for climate change mitigation. Short-rotation coppice willow is a potentially high-yielding energy crop that can be grown to supply a local energy facility. This study assessed the energy performance and climate impacts when establishing willow on current fallow land in a Swedish region with the purpose of supplying a bio-based combined heat and power plant. Time-dependent life cycle assessment (LCA) was combined with geographic information system (GIS) mapping to include spatial variation in terms of transport distance, initial soil organic carbon content, soil texture and yield. Two climate metrics were used [global warming potential (GWP) and absolute global temperature change potential (AGTP)], and the energy performance was determined by calculating the energy ratio (energy produced per unit of energy used). The results showed that when current fallow land in a Swedish region was used for willow energy, an average energy ratio of 30 MJ MJ(-1) (including heat, power and flue gas condensation) was obtained and on average 84.3 Mg carbon per ha was sequestered in the soil during a 100-year time frame (compared with the reference land use). The processes contributing most to the energy use during one willow rotation were the production and application of fertilizers (similar to 40%), followed by harvest (similar to 35%) and transport (similar to 20%). The temperature response after 100 years of willow cultivation was -6.10(-1)6 K MJ(-1) heat, which is much lower compared with fossil coal and natural gas (70.10(-16) K MJ(-1) heat and 35.10(-16) K MJ heat, respectively). The combined GIS and time-dependent LCA approach developed here can be a useful tool in systematic analysis of bioenergy production systems and related land use effects.

Keywords

bioenergy; geographic information system; global warming; land use; life cycle assessment; Salix; soil organic carbon; spatial variation

Published in

GCB Bioenergy
2017, volume: 9, number: 5, pages: 973-985

Authors' information

Hammar, Torun
Swedish University of Agricultural Sciences, Department of Energy and Technology
Swedish University of Agricultural Sciences, Department of Energy and Technology
Swedish University of Agricultural Sciences, Department of Energy and Technology
Royal Institute of Technology (KTH)

Sustainable Development Goals

SDG7 Affordable and clean energy
SDG13 Climate action

UKÄ Subject classification

Energy Systems
Climate Research

Publication Identifiers

DOI: https://doi.org/10.1111/gcbb.12399

URI (permanent link to this page)

https://res.slu.se/id/publ/81025