What Is Offshore Wind Energy?

Offshore wind energy is electricity generated by wind turbines installed in ocean waters, typically on the continental shelf where water depths range from 20 to 60 meters. Offshore wind resources are stronger and more consistent than onshore winds because there are no terrain features like hills, buildings, or forests to slow airflow. This means offshore turbines generate electricity at higher capacity factors, often exceeding 45% compared to 25% to 35% for onshore installations.

Modern offshore wind turbines are enormous. The latest generation of turbines reaches 15 megawatts or more per unit, with rotor diameters exceeding 230 meters. A single rotation of these blades can power a home for more than a day. These machines are mounted on fixed-bottom foundations driven into the seabed or, in deeper waters, on floating platforms anchored to the ocean floor.

How Offshore Wind Farms Are Built

Constructing an offshore wind farm is one of the most complex infrastructure projects in the energy sector. The process begins with years of environmental assessment, permitting, and engineering studies. Developers must secure federal leases from the Bureau of Ocean Energy Management, obtain state and local permits, and complete environmental impact reviews.

Construction requires specialized vessels. Jack-up installation vessels lift themselves above the waterline on extendable legs to create a stable platform for crane operations. Cable-laying vessels install the submarine power cables that connect turbines to each other and to the onshore grid connection point. The entire construction process for a large offshore wind farm can take three to five years from financial close to first power.

The US Offshore Wind Pipeline

The United States has ambitious offshore wind targets but has been slow to build compared to Europe and China. As of early 2025, the US had only about 175 megawatts of operational offshore wind capacity, consisting of the Block Island Wind Farm off Rhode Island and the first phase of the Vineyard Wind project off Massachusetts.

The federal pipeline is much larger. BOEM has issued leases for over 30 gigawatts of potential offshore wind capacity along the Atlantic coast, from Maine to the Carolinas. Additional lease areas have been designated in the Gulf of Mexico and off the coasts of California and Oregon. Several states have set aggressive procurement targets, with New York alone targeting 9 gigawatts by 2035.

Economics and Cost Challenges

Offshore wind has faced significant economic headwinds. Several major projects were cancelled or renegotiated in 2023 and 2024 as developers confronted rising costs for steel, turbines, and installation vessels, compounded by higher interest rates that increased financing costs. Contract prices that seemed viable when signed became unprofitable under new economic conditions.

Despite these setbacks, the long-term cost trajectory for offshore wind remains downward. European projects have demonstrated that costs decline with scale and experience. The levelized cost of offshore wind energy has fallen by more than 60% over the past decade globally. Building a domestic supply chain for vessels, components, and port infrastructure will be critical to reducing costs for US projects.

Floating Offshore Wind: The Next Frontier

Floating offshore wind technology opens up vast new areas of ocean where fixed-bottom foundations are not feasible due to water depth. The West Coast of the United States, with its deep continental shelf, is only accessible to floating wind technology. The same is true for much of the Gulf of Maine and significant areas off the Mid-Atlantic coast.

Several floating wind designs are in development, including semi-submersible platforms, spar buoys, and tension-leg platforms. The first commercial-scale floating wind farm, Hywind Scotland, has been operating since 2017. The US has designated floating wind lease areas off California and is actively pursuing additional areas along both coasts. Floating offshore wind remains more expensive than fixed-bottom technology, but costs are expected to decline rapidly as the first large-scale projects are built.