Life cycle assessment of hydropower utilization in Iceland as a driving force for climate strategy and decarbonization

Iceland’s energy and electricity needs are nearly fully met by renewable energy sources, hydropower and geothermal power. Hydropower is the country’s most important source of electricity, providing the population of Iceland with approximately 70% of its electricity. The aim of this study is to investigate and compare life cycle–based environmental impacts for four different hydropower stations situated around the country in three different regions, representing approximately 50% of installed hydropower in Iceland. All four stations utilize glacial rivers, diversions and reservoirs for electricity generation. The cradle-to-gate environmental impacts of electricity generation in the hydropower stations were evaluated throughout a 100-year life cycle using the standardized LCA methodology. System boundaries include initial resource extraction to material production, product manufacturing, use of the product and up to its disposal, including production wastes. Detailed information from the operator and its suppliers was provided for the life cycle inventory (LCI) and the life cycle impact assessment (LCIA) was performed using the LCA for Experts software (GaBi) and Sphera databases with results provided via the PEF methodology. The carbon footprint of electricity generated at the hydropower plants is on a range between 0.5 and 21.1 g CO2-eq per kWh, i.e. 0.5–1.5 g CO2-eq/kWh for three stations situated in E- and S-Iceland (Fljótsdalur, Búðarháls and Búrfell II stations), and 21.1 g CO2-eq/kWh for the Blanda station situated in NW-Iceland. For three out of four hydropower stations, the largest contributors to environmental impacts are manufacturing of components and fuel use during construction. In the case where a high level of organic matter has been inundated to create reservoirs, direct emissions due to the decomposition of organic matter is the most significant contributor to global warming impacts, eutrophication potential and photochemical ozone creation potential. The most carbon-intensive construction units are dams, tailrace and headrace tunnels and canals, and the station powerhouse. The results reveal that extensions of previously existing stations are highly feasible in terms of environmental performance. The study also reveals that optimal resource management and thus electricity generation is prevented by limitations in the transmission system, which would in turn improve environmental performance. In performing these assessments, important steps have been taken towards better understanding the environmental performance of renewable energy utilization, providing tools for necessary framework for climate policy making towards achieving a zero-carbon target.