Life cycle assessment of geothermal power plants: A comparison with other energy conversion technologies

Abstract

Geothermal is a very promising renewable energy, which differently from variable renewable energies is independent of external/climate conditions and can cover both power and heat demands. Nonetheless, albeit these advantageous characteristics, traditional geothermal power plants may have not negligible environmental impacts: these range from emissions of pollutants or greenhouse gases to relevant use of chemicals, power, and other resources during plant development (wells), operation, and construction.It is therefore of paramount importance to provide a reliable methodology to assess the environmental performance of geothermal systems, which should also allow a comparison of the effects with other renewable energies and with traditional fossil fuels used in the power and heat sector.For this reason, Life Cycle Assessment (LCA) was selected as the proper tool to conduct the comparison. An updated analysis of several representative geothermal power plant reference cases of different types and sizes was performed using the Product Environmental Footprint EF 2.0 assessment method. This represents also an update concerning the current practice documented in the technical literature, which often applies different methods (e.g. RECIPE, ILCD, CML, or Eco-Indicator) which are being superseded.In this research, the final single score of each power plant was also calculated and compared among different plants, as well as with other renewables and national energy mixes. The single score results indicate that geothermal plants' environmental impacts are in line with other renewable technologies and that they are in general lower than the corresponding national energy mixes.