In 2008, the U.S. Department of Energy (DOE) embarked on a research and development program that seeks to increase the portion of energy generated by wind to 20% by 2030. Of the projected 300 GW (1 GW = 1 gigawatt = 109 watts) needed to meet this goal, 54 GW is expected to come from offshore wind energy, enough to power about 16 million homes. Already, land-based wind energy generation realized since 2008 has exceeded DOE’s projections. On the other hand, not a single offshore wind turbine has been installed in US waters to date. This is expected to change within the next 5-10 years.
There are many reasons why offshore wind energy is especially important today. Land-based wind energy sites are often far from load centers. Our energy needs are greater near heavily urbanized regions, which are often close to coastlines. Siting wind turbines offshore reduces the need for long transmission lines that are essential when wind energy has to be delivered from distant rural sites (as is the case in Texas, the energy produced in the Panhandle region with its excellent wind resource is delivered to cities like Austin and Dallas). Avoiding such infrastructure costs, as well as inevitable losses in the transmission, is possible with offshore wind energy development. Additionally, winds over oceans are often stronger, more sustained, and smoother or less turbulent—this translates to a higher quality wind resource that, at the same time, puts less structural demands on the wind turbine system.
Still, there are many technical challenges with offshore wind. Offshore wind projects in other parts of the world have not had to deal with deep waters (at many potential US coastal sites, the continental shelf drops off more steeply) that require more innovative turbine support structures compared to situations abroad where simpler monopole foundations have been adequate.
A far greater concern has been the need to design turbines to withstand hurricanes, especially for potential Gulf of Mexico and Atlantic Seaboard sites. Professor Lance Manuel and PhD student Eungsoo Kim are collaborating with the National Renewable Energy Laboratory (NREL) and the University of Miami’s Rosenstiel School of Marine & Atmospheric Science (RSMAS) on a two-year DOE-funded project that is seeking to assess the structural demands on offshore wind turbines for coupled wind, wave, and current inputs during a hurricane.
The team is undertaking studies involving numerical simulation of Hurricane Ike and the associated response of hypothetical wind turbines that experience Ike’s extreme winds and coupled ocean waves and current fields. They are also studying risks to jacket platform-supported wind turbines at several potential mid-Atlantic coastal sites during Superstorm Sandy, where complex wind, wave, currents, and storm surge patterns were observed.
Findings from this research study are expected to provide useful guidance to DOE in terms of design standard definition and in making decisions related to future offshore wind energy development in US waters and to decisions related to future offshore wind energy development in the US.
