Life Cycle Greenhouse Gas Emissions of Crystalline Silicon Photovoltaic Electricity Generation
Systematic Review and Harmonization
Version of Record online: 19 MAR 2012
© 2012 by Yale University
Journal of Industrial Ecology
Special Issue: Meta-Analysis of Life Cycle Assessments
Volume 16, Issue Supplement s1, pages S122–S135, April 2012
How to Cite
Hsu, D. D., O’Donoughue, P., Fthenakis, V., Heath, G. A., Kim, H. C., Sawyer, P., Choi, J.-K. and Turney, D. E. (2012), Life Cycle Greenhouse Gas Emissions of Crystalline Silicon Photovoltaic Electricity Generation. Journal of Industrial Ecology, 16: S122–S135. doi: 10.1111/j.1530-9290.2011.00439.x
- Issue online: 3 MAY 2012
- Version of Record online: 19 MAR 2012
- global warming;
- industrial ecology;
- renewable energy;
- life cycle assessment (LCA);
Published scientific literature contains many studies estimating life cycle greenhouse gas (GHG) emissions of residential and utility-scale solar photovoltaics (PVs). Despite the volume of published work, variability in results hinders generalized conclusions. Most variance between studies can be attributed to differences in methods and assumptions. To clarify the published results for use in decision making and other analyses, we conduct a meta-analysis of existing studies, harmonizing key performance characteristics to produce more comparable and consistently derived results.
Screening 397 life cycle assessments (LCAs) relevant to PVs yielded 13 studies on crystalline silicon (c-Si) that met minimum standards of quality, transparency, and relevance. Prior to harmonization, the median of 42 estimates of life cycle GHG emissions from those 13 LCAs was 57 grams carbon dioxide equivalent per kilowatt-hour (g CO2-eq/kWh), with an interquartile range (IQR) of 44 to 73. After harmonizing key performance characteristics (irradiation of 1,700 kilowatt-hours per square meter per year (kWh/m2/yr); system lifetime of 30 years; module efficiency of 13.2% or 14.0%, depending on module type; and a performance ratio of 0.75 or 0.80, depending on installation, the median estimate decreased to 45 and the IQR tightened to 39 to 49. The median estimate and variability were reduced compared to published estimates mainly because of higher average assumptions for irradiation and system lifetime.
For the sample of studies evaluated, harmonization effectively reduced variability, providing a clearer synopsis of the life cycle GHG emissions from c-Si PVs. The literature used in this harmonization neither covers all possible c-Si installations nor represents the distribution of deployed or manufactured c-Si PVs.