Life Cycle Analysis to estimate the environmental impact of residential photovoltaic systems in regions with a low solar irradiation

摘要

Photovoltaic installations (PV-systems) are heavily promoted in Europe. In this paper, the Life Cycle Analysis (LCA) method is used to find out whether the high subsidy cost can be justified by the environmental benefits. Most existing LCAs of PV only use one-dimensional indicators and are only valid for regions with a high solar irradiation. This paper, however, presents a broad environmental evaluation of residential PV-systems for regions with a rather low solar irradiation of 900-1000 kWh/m~2/year, a value typical for Northern Europe and Canada. Based on the Ecoinvent LCA database, six Life Cycle Impact Assessment (LCIA) methods were considered for six different PV-technologies; the comprehensive Eco-Indicator 99 (El 99) with its three perspectives (Hierarchist, Egalitarian and Individualistic) next to three one-dimensional indicators, namely Cumulative Energy Demand (CED), Global Warming Potential (GWP) and the Energy Payback Time (EPT). For regions with low solar irradiation, we found that the EPT is less than 5 years. The Global Warming Potential of PV-electricity is about 10 times lower than that of electricity from a coal fired plant, but 4 times higher when compared to a nuclear power plant or a wind farm. Surprisingly, our results from the more comprehensive El 99 assessment method do not correlate at all with our findings based on EPT and GWP. The results from the Individualist perspective are strongly influenced by the weighting of the different environmental aspects, which can be misleading. Therefore, to obtain a well-balanced environmental assessment of energy technologies, we recommend a carefully evaluated combination of various impact assessment methods.