Life cycle assessment of a high-altitude photovoltaic power plant in the Swiss Alps

Switzerland has committed to becoming climate-neutral by 2050. Achieving this goal is closely linked to the government's energy strategy, which provides for the significant expansion of renewable energies alongside other measures. Due to the substitution of fossil fuels in mobility & heat supply and the simultaneous decommissioning of Swiss nuclear power plants, which currently account for 35% of Swiss electricity production, without additional measures an electricity production gap of 35 TWh is expected in 2050. It is assumed that additional photovoltaic (PV) plants will have to close this electricity gap, as the expansion of hydropower and wind power in Switzerland is limited. The expansion of PV plants in Switzerland is mainly taking place in the urban and densely populated midlands. As PV plants in the midlands generate 30% of annual electricity production in winter, but more electricity is needed in winter than in summer, a so called winter energy gap is generated. PV plants at higher altitudes can help to close this winter energy gap. PV power plants at higher altitude produce similar amount of electricity in winter as in summer. Since no study on the ecological impact of high-altitude PV plants has been conducted so far, this work aims to answer the research question on the ecological footprint of a PV plant at higher altitudes with a life cycle assessment based on a case study in Switzerland. The case study is a planned PV plant on Mount Gibidum, where almost 65’000 bifacial mono-Si panels will produce 40 GWh of electricity annually on an area the size of 38 soccer fields. For the LCA, all stages of the life cycle were taken into account, from the manufacture of the components to the construction of the plant and its operation to dismantling and disposal. The functional unit was defined as 1 kWh of AC electricity produced and fed into the electricity grid. The global warming potential according to the IPCC, the total environmental impact according to the ecological scarcity method and selected impact categories at midpoint level according to the Environmental Footprint method version 3.1 were analyzed in the life cycle impact assessment (LCIA). The results show that the global warming potential of the electricity produced by the high-altitude PV plant is 32 g CO2 eq / kWh. The greenhouse gas emissions are mainly attributable to the two hotspots: (1) PV panels and (2) ground mounting system. The impact assessment using the ecological scarcity method also shows the same two hotspots with a total environmental impact of 64 ecopoints per kWh of electricity produced. From a life cycle assessment perspective, the further expansion of ground-mounted PV systems in the urban lowlands is not recommended. In order to close the winter electricity gap with PV plants, ground-mounted PV plants at higher altitudes are an important option, as the net benefit of substitution of the Swiss electricity mix is higher than with PV plants in the lowlands. However, ground-mounted PV plants at higher altitudes should only be built after a detailed assessment of the local flora and fauna in order to minimize the loss of biodiversity.