Abstract

Forest residues can be left at the harvest site to gradually decompose, or can be collected for energy purposes. This study analyzes the primary energy and climate impacts of bioenergy systems where forest residues are collected and used for electricity, heat and transportation, compared to fossil-based energy systems where fossil fuels provide the same services while forest residues are left on site to decompose. Time profiles are elaborated of primary energy use and carbon dioxide emissions from various energy applications fulfilled by bioenergy or fossil energy systems. Different biological decay functions are considered based on process-based modeling and inventory data across various climate zones. For all scenarios, the changes in cumulative radiative forcing (CRF) are calculated over a 300-year period, to evaluate the short- and long-term contributions of forest residue to climate change mitigation. A life cycle perspective along the full energy chains is used to evaluate the overall effectiveness of each system. The results show largest primary energy and climate benefits when forest residues are collected and used efficiently for energy services. Using biomass to substitute fossil coal provides greater climate change mitigation benefits than substituting oil or fossil gas. Some bioenergy substitutions result in positive CRF, i.e. increased global warming, during an initial period. This occurs for relatively inefficient bioenergy conversion pathways to substitute less carbon intensive fossil fuels, e.g. biomotor fuel used to replace diesel. More beneficial bioenergy substitutions, such as efficiently replacing coal, result immediately in reduced CRF. Biomass decay rates and transportation distance have less influence on climate benefits. (C) 2014 Elsevier Ltd. All rights reserved.

Keywords

Forest residues; Primaiy energy; Carbon dioxide; Radiative forcing; Fuel substitution

Published in

Applied Energy
2015, Volume: 138, pages: 36-50

SLU Authors

• Josefsson Ortiz, Carina

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

SDG7 Ensure access to affordable, reliable, sustainable and modern energy for all
SDG13 Take urgent action to combat climate change and its impacts
SDG12 Ensure sustainable consumption and production patterns


UKÄ Subject classification

Environmental Management
Energy Systems
Soil Science


Publication identifier

DOI: https://doi.org/10.1016/j.apenergy.2014.10.013

Permanent link to this page (URI)

https://res.slu.se/id/publ/63973