| The increasing demand for electricity worldwide calls for a comparative assessment of the various electricity generation technologies in terms of their global impact. A comprehensive analysis of electricity generation should include the life-cycle assessment (LCA) of emissions from each option. Although the spatial distribution of greenhouse gas (GHG) emissions over the life-cycle of an energy system does not affect the impacts on climate change, the timing of the release affects the future airborne fraction. The Global Warming Effect (GWE) framework draws on climate science to compare and aggregate GHG emissions over the life-cycle of power plants. Data for LCA are either available from economic input-output analysis-based LCA or are obtained through process-based LCAs. Because a reasonable understanding exists of GHG balance after changes in land use, this knowledge is also incorporated in the comparison of global impacts of different alternatives in the electricity supply. The assessment includes GHG emissions from manufacturing, construction, burning of fuels, maintenance, flooded biomass decay in the reservoir, loss of net ecosystem production, and land use. The GWE is implemented in an electronic spreadsheet to facilitate the interaction of the user with the method and increase its transparency. Various choices, assumptions and uncertainties have been made explicit. The period of analysis is at the discretion of the analyst; however, irrespective of the selection, results of case studies indicate that a wind farm appears to have lower GWE than other comparable alternatives. The performance of hydroelectric plants depends on the type of ecosystem displaced and its net ecosystem production, i.e., the difference between the CO 2 equilibrium between the atmosphere and the terrestrial ecosystem before the reservoir filling, and the balance between atmosphere and the aquatic ecosystem after the reservoir filling, including emissions from sediments due to decommissioning of dams. The GWE framework intends to connect local decision-making to global climate change. |
