An Integrated Assessment of Offshore Wind Farm Siting: A Case Study in the Great Lakes of Michigan
Offshore wind farm (OWF) siting is crucial in determining the success of wind energy projects relative to multiple objectives, including increasing energy generation, decreasing installation costs, reducing life-cycle environmental impacts, displacing pollutant emissions, and reducing visual impact of wind turbines. This study examines the performance across these objectives for twenty siting scenarios in four Great Lakes counties and at various offshore distances. To evaluate wind energy potential of remote sites using wind-speed profiles, the shape parameter of the Weibull distribution of wind speeds at known weather stations was extrapolated using geostatistical kriging (Ch. 2). The best estimate of the shape parameters at candidate OWF locations varied from 1.73 to 1.82, indicating that the commonly used value of 2 may over-estimate the wind speed distribution at wind speeds that wind turbines can generate electricity. Life-cycle environmental impacts of OWFs were evaluated using a process-based life cycle assessment for a 100 x 3MW OWF at twenty sites (Ch.3). The OWF manufacture, transportation, installation, use phase, and decommissioning contribute that, on average, one kWh of delivered electricity from OWFs will lead to global warming potential (GWP), acidification potential (AP), and cumulative energy demand (CED) impacts of 36 g CO2eq, 0.012 mole H+eq, and 0.14 kWh fossil fuel, respectively. Another OWF externality resulting from negative visual impacts was characterized and valued by combining viewshed simulation with estimates of willingness to pay data for moving wind turbines farther offshore (Ch. 4). Finally, an integrated assessment of OWF siting investigated the trade-offs between four objectives: energy, economy, environment, and society. The multiple criteria decision analysis with subjective weighting, objective weighting and monetization approaches are compared to illustrate different preferences and values toward OWF objectives (Ch. 6). The results of this study are expected to provide more diversified information of wind energy projects for stakeholders and decision makers. Meanwhile, the findings can inform wind-energy-related policy in order to maximize the benefits of OWFs to the society as a whole.