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Building the Foundation: How Offshore Wind Projects are Developed
Developing an offshore wind project in the United States is a complex multiyear endeavor. It involves all levels of government, the power and labor of several industrial sectors, and the input of scientists, engineers, and the general public. This page will introduce you to some of the key government agencies, technologies, and processes that take an offshore wind farm an idea to a functioning power plant.
CESA publishes a new installation of "Building the Foundation" in every Offshore Wind Accelerator Newsletter. Subscribe to never miss a new post.
Anatomy of a Wind Turbine
From CESA's December 2023 OWA Newsletter
1. Foundations are enormous steel or concrete structures that anchor the turbine to the sea floor. The specific type of foundation used depends on the turbine’s depth and the composition of the seafloor. Fixed-bottom turbines typically use monopiles (large steel tubes), gravity foundations (wide and heavy concrete bases), or jackets (three- or four-legged steel structures) as a platform for the turbine. Monopiles are hammered into the seafloor using a piledriver, while gravity and jacket foundations typically use suction to stay in place. Foundation technology for floating turbines is less standardized but are often ballasted concrete tubes or very wide concrete platforms that float in the water. They usually use one or a series of heavy lines or cords that are moored to the seafloor to keep the foundation in place. Foundations are always the first structures installed at a wind farm.
2. Transition Pieces are large steel tubes that connect foundation to the turbine’s tower. In addition to connecting the underwater and above-water components, they also serve as a platform for wind turbine technicians to get onto the structure. They are the second piece installed after the foundation, and they are often painted yellow or another bright color.
3. Towers are the extremely tall steel tubes that give the turbines their height, often soaring taller than the Statue of Liberty. Since it’s impossible to build and transport such a tall structure in one piece, towers are typically three steel tubes connected together with rivets. The pieces are connected onshore, loaded onto the wind turbine installation vessel, and then brought out to the installation site.
4. Nacelles sit atop the tower and convert the rotation of the blades into electrical power. The spinning turbines rotate gears in the nacelle that turn a powerful set of magnets, generating an electrical current. Nacelles on offshore wind turbines are large enough for a person to fit inside them.
5. Blades, the most recognizable part of a wind turbine, spin as wind flows cross their surface, driving the gears in the nacelle. Blades are made of carbon fiber or other plastic-composite materials molded into shape using heat. Unlike towers, blades cannot be assembled in pieces—this makes transporting them a delicate and expensive part of the process. Each blade is typically longer than a football field, and at their base, they are wide enough for a person to fit inside them.
Check out these resources to learn more about how wind turbines work and how they are engineered:
- Ørsted – How Do Offshore Wind Turbines Work? (article)
- Iberdrola – Offshore Wind Turbines Foundations (article)
- NREL WINDExchange – Technology Below the Water (webinar)
- NREL WINDExchange – Technology Above the Water (webinar)