Offshore Wind, Wave and Tidal Energy

offshore wind turbines

Wind Turbine Evolution to Deeper Water
(Credit: National Renewable Energy Laboratory)

Harnessing energy from offshore winds, waves, and tides holds great promise for our nation's clean energy future. Energy production is just one of the valuable resources our oceans and coastal ecosystems provide. We can successfully develop offshore renewable energy by ensuring that energy projects are sited, designed, and constructed in a manner that protects our fragile ocean ecosystems.

How Offshore Renewable Energy Works

offshore wave buoy

Ocean Power Technologies wave buoy (Credit: Ocean Power Technologies, Inc.)

Offshore Wind

Energy from offshore wind is generated from wind turbines, similar to land-based turbines, which are usually attached to the sea bed using a fixed foundation. In deeper waters, floating platforms are needed to support the wind turbines. Several types of floating platform technologies are under development. When the wind blows, the blades of the turbine rotate and power a generator that converts wind energy into electricity. The electricity is typically transported to shore through cables along the ocean floor. As technology advances, offshore wind turbines will increase in size and efficiency, enabling them to be moved farther out to sea, where they will harness stronger winds, and produce even more energy at a lower cost.

Waves, Tides, and Currents

Marine hydrokinetic energy comes from the energy contained in waves, tides, or ocean currents. The devices that harness this energy are among the newest renewable technologies. They range from buoys, to clam-like shells on the sea bottom, to underwater versions of wind turbines. Many of them are still being tested and refined.

Advantages of Offshore Renewable Energy

Offshore renewable energy is an untapped resource in the United States, and has the potential not only to add to our clean energy mix, but to create jobs as well. Building and maintaining offshore energy facilities is labor and material intensive, requiring everything from turbine blades to skilled technicians. Developing this energy resource has the potential to create tens of thousands of good jobs all along the supply chain.

The National Renewable Energy Laboratory estimates that the United States could harvest 54 gigawatts (GW) from offshore wind by 2030 -- enough to power more than 42 million homes. This would generate an estimated $200 billion in new economic activity and create more than 43,000 permanent, well-paid jobs.

Where Offshore Renewable Energy is Used

Offshore wind energy is up and running in many places around the world. In Europe, some 53 offshore wind projects, totaling almost 3,800 megawatts (MW) of capacity, are producing clean renewable energy off the coasts of 10 European countries, with nine more major offshore wind projects under construction. The Walney wind farm off Cumbria, Great Britain, is the largest in the world, with more than 100 turbines generating 367 megawatts -- enough power for 320,000 homes. China recently built its first offshore wind project, and has more underway.

In the United States, the East Coast holds the most promise for offshore wind energy development. Wave energy potential is stronger off California and Oregon, while Alaska and Maine have the large tide differences necessary to generate tidal energy.

What's Around the Corner for Offshore Renewable Energy

So far, there are no offshore wind farms in U.S. waters, but there are a number of projects under development. According to the NREL, about 20 projects representing more than 2,000 megawatts of capacity are in the planning and permitting process, mostly in the Northeast and Mid-Atlantic, although projects are also being considered along the Great Lakes, the Gulf of Mexico, and the Pacific Coast.

offshore underwater turbine

Verdant Power's Free Flow System (Credit: Verdant Power)

The Cape Wind Project, in federal waters off the coast of Massachusetts, has been approved by the federal government with support from NRDC. Wave, tidal, and current projects are also being tested at a small scale to assess and reduce any negative ocean impacts and make adjustments to improve efficiency and compatibility with existing uses of the ocean.

Recently, Verdant Power received approval to build the first commercial tidal power project in the United States, in New York City's East River, off Roosevelt Island, with thirty underwater tidal turbines. The East River's four-mile-per-hour current will spin the blades of the 20-foot-tall turbines, which are just six to eight feet below the surface. That creates electricity, which will be run through a large cable along the river's floor.

Ensuring that offshore renewable energy projects are sustainably sited, designed and built will help minimize conflicts with sensitive marine habitat and with human activities in the water. The process of marine spatial planning will help all interested stakeholders decide on the best places to develop offshore renewable energy.

Offshore Renewable Energy Meets Ocean Conservation

Certain ecologically sensitive marine areas are not appropriate for energy development. In some of these places, energy development is prohibited or limited by law or policy, and in others it would be highly controversial. NRDC does not endorse locating energy facilities or transmission lines in such areas. Siting decisions must always be made extremely carefully, with impacts mitigated and operations conducted in an environmentally responsible manner.

NRDC uses expertise in renewable energy, ocean policy, law and financing to help move offshore renewable energy forward sustainably. We ensure thorough environmental review of the potential impacts of offshore renewable energy projects on sensitive marine life, such as whales, migrating birds, fish and threatened or endangered species. We support careful planning, using the best available data and technology, to ensure the appropriate siting, construction and operation of offshore renewable energy.

Learn More

European Marine Energy Centre Ltd
Provides information on ocean wave and tidal energy capture.
Learn about Ocean Energy
NREL provides an overview of ocean energy technologies.
National Marine Energy Centers
Sponsored by DOE, National Marine Energy Centers are housed in three public universities:
University of Washington, University of Hawaii, and Oregon State University.
NOAA Office of Habitat Protection
Offers general information on the types of emerging ocean thermal and hydrokinetic technologies and developing thorough processes for appropriate siting. The agency's comments on specific projects are also available online.
Oregon Wave Energy Trust
The Trust's sole mission is to serve as a connector for all stakeholders involved in the responsible development of wave energy projects, from research and development to early stage community engagement and energy generation in the State of Oregon.
Ocean Renewable Energy Coalition
The Ocean Renewable Energy Coalition is a national trade association that serves as a clearinghouse for information on marine and hydrokinetic energy technologies.
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