Open AccessTime‐dependent climate impact of a bioenergy system – methodology development and application to Swedish conditions
Author(s) -
Ericsson Niclas,
Porsö Charlotta,
Ahlgren Serina,
Nordberg Åke,
Sundberg Cecilia,
Hansson PerAnders
Publication year - 2013
Publication title -
gcb bioenergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.378
H-Index - 63
eISSN - 1757-1707
pISSN - 1757-1693
DOI - 10.1111/gcbb.12031
Subject(s) - bioenergy , environmental science , carbon neutrality , climate change , biomass (ecology) , willow , life cycle assessment , greenhouse gas , short rotation coppice , climate change mitigation , fossil fuel , land use, land use change and forestry , carbon sequestration , land use , renewable energy , carbon dioxide , ecology , production (economics) , economics , biology , macroeconomics
The area of dedicated energy crops is expected to increase in Sweden. This will result in direct land use changes, which may affect the carbon stocks in soil and biomass, as well as yield levels and the use of inputs. Carbon dioxide ( CO 2 ) fluxes of biomass are often not considered when calculating the climate impact in life cycle assessments ( LCA ) assuming that the CO 2 released at combustion has recently been captured by the biomass in question. With the extended time lag between capture and release of CO 2 inherent in many perennial bioenergy systems, the relation between carbon neutrality and climate neutrality may be questioned. In this paper, previously published methodologies and models are combined in a methodological framework that can assist LCA practitioners in interpreting the time‐dependent climate impact of a bioenergy system. The treatment of carbon differs from conventional LCA practice in that no distinction is made between fossil and biogenic carbon. A time‐dependent indicator is used to enable a representation of the climate impact that is not dependent on the choice of a specific characterization time horizon or time of evaluation and that does not use characterization factors, such as global warming potential and global temperature potential. The indicator used to aid in the interpretation phase of this paper is global mean surface temperature change (Δ T s ( n )). A theoretical system producing willow for district heating was used to study land use change effects depending on previous land use and variations in the standing biomass carbon stocks. When replacing annual crops with willow this system presented a cooling contribution to Δ T s ( n ). However, the first years after establishing the willow plantation it presented a warming contribution to Δ T s ( n ). This behavior was due mainly to soil organic carbon ( SOC ) variation. A rapid initial increase in standing biomass counteracted the initial SOC loss.