Offshore Wind Farm Layout Optimization (OWFLO) Project: Preliminary Results

Optimizing the layout of an offshore wind farm presents a significa nt engineering challenge. Most of the optimization literature to date has focused on land -based wind farms, rather than on offshore farms. Typically, energy production is the metric by which a candidate layout is evaluated. The Offshore Wind Farm Layout Optimization (OWFLO) project instead uses the levelized production cost as the metric in order to account for the significant roles factors such as support structure cost and operation and maintenance (O&M) play in the design of an offshore wind farm. The objective of the project is to pinpoint the major economic hurdles present for offshore wind farm developers by creating an analysis tool that unites offshore turbine micrositing criteria with efficient optimization algorithms. This tool will then be use d to evaluate the effects of factors such as distance from shore and water depth on the economic feasibility of offshore wind energy. The project combines an energy production model —taking into account wake effects, electrical line losses, and turbine avai lability —with offshore wind farm component cost models. The components modeled include the rotor -nacelle assembly, support structure, electrical interconnection, as well as O&M, installation, and decommissioning costs. The models account for the key cost drivers, which include turbine size and rating, water depth, distance from shore, soil type, and wind and wave conditions. When integrated within an appropriate optimization routine, these component models work together to better reflect the real -world c onditions and constraints unique to individual offshore sites. The OWFLO project considers several optimization algorithms —including heuristic and genetic methods —to minimize the cost of energy while maximizing the energy production of the wind farm. Par ticular attention has been paid to the results of recent European studies, including the ENDOW and DOWEC projects. This paper summarizes the initial results from this project. A comparison of model results and data from the Middelgrunden offshore wind far m is presented. The overall energy and cost of energy estimations compare well with the real data, but further improvements to the models are planned. A summary of the on -going and future phases of the project is also presented.