Influence of Salix variety on climate impact of different biomass conversion routes

Abstract

One key strategy to combat global warming is to reduce greenhouse gas (GHG) emissions by substitution of conventional fossil fuels and products with biomass based alternatives. Salix is a perennial crop providing fast growing biomass with low resource use, and have potential benefits for soil and climate mitigation. Several varieties of Salix have been developed, with differences in characteristics, including yield, morphology, chemical composition and physiology.

The aim of this thesis was to enhance understanding of the effect of Salix varieties on climate impact of various biomass conversion routes from a life cycle perspective. Six commercial Salix varieties and three conversion routes were analysed: combustion for heat, anaerobic digestion for compressed biomethane gas (CBG), and fermentation for yeast oil. The assessment included a time dynamic life cycle assessment method using variety specific field and laboratory data, and modelling of soil organic carbon (SOC) changes.

The results demonstrated that converting Salix biomass to heat and CBG across all varieties resulted in lower climate impact compared to fossil energy sources. Yeast oil from the Salix varieties exhibited a similar or lower net climate impact compared to Swedish rapeseed oil. Salix cultivation under the site conditions increased SOC stocks, contributing notably to climate mitigation. The yield and SOC sequestration potential of Salix varieties had the strongest influence on the climate impact of the analysed conversion routes. The SOC increase was not dependent on yield, but was instead influenced by variety and fertilisation. Varieties with high yields had a larger substitution effect, resulting in greatest climate mitigation per unit of land. While the SOC sequestration potential was more critical in determining climate impact per unit of product. The temporary carbon stored in the live biomass had a strong but short lived cooling effect on the time dependent climate impact.

Keywords

willow; soil carbon modelling; life cycle assessment; LCA; bioenergy; biomethane; biolipid; time dependent climate impact

Published in

Acta Universitatis Agriculturae Sueciae
2024, number: 2024:70ISBN: 978-91-8046-361-4, eISBN: 978-91-8046-397-3Publisher: Swedish University of Agricultural Sciences

SLU Authors

• Kalita, Saurav

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Energy Engineering
Climate Research


Publication identifier

DOI: https://doi.org/10.54612/a.3bia7u6278

Permanent link to this page (URI)

https://res.slu.se/id/publ/130465