Advancing Offshore Wind Power Siting through Multi-criteria Assessment Integration
There are two major goals for this project. The first is to advance offshore wind siting methods by utilizing multi-criteria assessment that includes concepts and methods from life cycle assessment (LCA), geographic information systems (GIS), viewshed modeling, aquatic ecology, and economics to analyze the consequences of design, policy, and engineering decisions of offshore wind farm siting. By accomplishing this task, offshore wind siting assessment can integrate the many competing siting objectives within a cohesive evaluation environment, and a general methodology will be developed for site evaluation. The second task is to apply this multi-criteria methodology to the Great Lakes region to explore how offshore wind farm siting locations will impact the electric sector, environmental quality (through emissions reductions and aquatic life impacts), and local view sheds. The completion of this task will help inform the development of policy and technology with respect to offshore wind turbines, and provide tools for conducting these analyses.
This research will develop and integrate two important methods that will provide a more comprehensive evaluation of offshore wind turbine siting often overlooked in current evaluations: viewshed impacts, and aquatic ecosystem impacts. These two components can be integrated with an evaluation of the costs of installation, energy production potential, and pollution abatement. A viewshed is an area or landscape visible to the human eye, and wind siting proposals have often met opposition by not properly evaluating the viewshed impact of wind turbine placement. The impacts of offshore wind turbines in Great Lakes aquatic ecosystems may have positive components because their structures may create new habitats for native fish as protected and nursery areas but may also have negative effects as they will eliminate suitable habitat for benthic organisms, and create new suitable substrate for settlement of invasive Dreissena mussels. These effects will eventually result in changes to the ecosystem food webs and potentially on fisheries. Both viewsheds and aquatic ecosystems play an important economic role in the livelihoods of the regions where offshore wind farms would be planned. This research develops tools for a geospatial evaluation of viewshed and ecosystem impacts, and applies them to several case studies in Lake Michigan and the Saginaw Bay area of Lake Huron.
The proposed research effort will develop a multi-criteria analysis that uses GIS, LCA, and optimization methods to both analyze and visualize the economic, environmental, and social impacts of siting offshore wind turbines. Key metrics for evaluation are willingness to pay (social cost), life cycle impacts (e.g. greenhouse gas emissions) (environmental cost), fishery population changes (environmental cost), and the life cycle cost of electricity for the wind farm (economic).
This research will evaluate three research themes that will be examined simultaneously to explore the tradeoffs that they have within the context of the Great Lakes case study. The modeling will elucidate tradeoffs that will be visualized with GIS maps.
- Viewshed impacts of offshore wind farms. The distance to shore metric is used to define how far from shore a wind turbine must be placed. The turbine distance from shore and the topography of the shoreline, and surrounding area, will impact the visibility of the wind turbines. Since topology is not consistent across locations it is expected that viewsheds will be different at different siting locations that are the same distance from the shore. This will highlight the need for policy that considers more than just distance from shore for wind turbine siting.
- Distance to shore of wind farm and project costs. The cost of installing offshore wind turbines generally increases as their distance from the shore increases. Transmission line costs should be similar across different sites based on distance. However, the bathymetry of a body of water will indicate the type, and costs, of viable turbine foundations due to seabed depth. Therefore, distance from shore policies may need to be considered in combination with water depth.
- Effects on aquatic ecology and the food web of the Great Lakes. Offshore structures will create refuge areas for adult and juvenile fish decreasing mortality that will result in positive effects for Great Lakes economies through revenues from fisheries. Offshore structures will decrease suitable habitat for benthic organisms that are prey for fish populations and reduced habitat will result in population declines of some fish species. The Great Lakes aquatic ecosystems have been greatly impacted by invasive Dreissena mussels. This has caused food web disruptions with consequent decline in fish populations and economic hardship for the region. The introduction of turbine foundations into the water will create prime substrate for Dreissena and result in increases in population numbers with further consequences to the ecosystems.
Three videos were produced as part of this project. Click on links below to view the videos:
- Part 1 - Wind Farm Siting: A Resource for Communities
- Part 2a - Onshore Wind Power Plant Siting
- Part 2b - Offshore Wind Power Plant Siting