COMPARING LIFE-CYCLE ENVIRONMENTAL IMPACTS OF ELECTRICITY GENERATION SYSTEMS

Significant public discussion and policy decisions surround the broad topics of how best to decarbonize the electricity sector and the potential supply of material needed to support these efforts. Research is needed to understand and quantify trade-offs among society’s goals of mitigating climate change, providing reliable and affordable energy, and improving local environments that can sustain the current population of 8 billion people. The goals of this research are to better understand potential environmental risks across global supply chains; highlight where impacts can be mitigated; and, inform policies that encourage innovation. We achieve these goals by conducting a comparative life-cycle assessment (LCA) of five generation systems, including natural gas-fired combined cycle gas turbines, and wind and solar power plants, with and without batteries (to address intermittencies). We assess environmental impacts for 18 different pathways, covering greenhouse gas and local (PM, SO_X, NO_X) emissions; land and water use and pollution, biodiversity and ecosystem services, and others. Geosciences plays a vital role in these LCA analyses, by considering extraction of natural resources (gas, minerals, etc.), manufacturing of generation equipment, power plant operations, and end-of-life. Our area of interest for electricity generation is west Texas. We show how environmental impacts are manifested along global supply chains needed to support energy development, at different times during the 30-year lifespan of the facilities. For example, CO₂ emissions are elevated early in the construction phase of wind and solar (at locations mostly overseas), but CO₂ emissions from combustion at the CCGT plant in west Texas eventually exceed that from wind and solar. Alternatively, results indicate that particulate matter formation and ecotoxicity are higher for wind/solar/batteries than CCGT, throughout the life cycle, because of higher material processing and refining needs. Other relationships are discussed. The results show the complicated nature of the environmental impacts along the global supply chain of materials needed for energy development, and the importance of geosciences, and they point to areas where impacts can be mitigated through innovation and action.