Ocean Energy Resources

The oceans' waters, the air above the oceans, and the land beneath them contain enormous energy resources.

	GOES Satellite Image

Oceans cover almost three-fourths of the earth’s surface. The oceans' waters, the air above the oceans, and the land beneath them contain enormous energy resources. These energy resources include non-renewable energy sources such as oil and gas, and renewable energy sources, such as offshore wind energy, wave energy, ocean current energy, offshore solar energy. Offshore renewable resources are the focus of the OCS Alternative Energy Programmatic EIS.

Ocean Energy Resources and Their Utilization

In many areas, large deposits of petroleum and natural gas are buried under the seabed. Today, more than a fourth of the oil and gas produced in the United States comes from offshore areas, and many other countries have extensive offshore oil and gas facilities as well. In contrast, relatively few countries have extensive offshore renewable energy facilities, and in the U.S., offshore renewable energy technologies are currently little utilized for commercial energy generation. The technologies are relatively new, and historically they have not generally been economically competitive with traditional non-renewable energy sources such as oil, gas, and coal.

More recently, as the prices of traditional energy sources such as gas and coal continue to climb, and the design and efficiency of offshore renewable energy technologies improves, these energy sources are becoming more economically competitive with traditional energy sources. The alternative energy sources under consideration for use on the OCS—wind, solar, wave, and current power—hold significant potential to alleviate the growing energy demands of society. As a result, interest in using these technologies for commercial energy generation in the U.S. is increasing, and the the Energy Policy Act of 2005, authorizes the Department of the Interior to grant leases, easements or rights-of-way on the U.S. Outer Continental Shelf (OCS) for the development and support of energy resources other than oil and gas.

Ocean Thermal and Mechanical Energy

The waters of the oceans can produce two types of energy: thermal energy from the sun's heat, and mechanical energy from tides and waves.

Ocean Thermal Energy

Oceans cover more than 70% of Earth's surface, making them the world's largest solar collectors. The sun's heat warms the surface water a lot more than the deep ocean water, and this temperature difference creates thermal energy. Ocean thermal energy can be used for many applications, including electricity generation. While the the OCS Alternative Energy Programmatic EIS will examine ocean current energy, which is based primarily on thermal energy that drives ocean currents, it does not consider other ocean thermal energy technologies, such as ocean thermal energy conversion systems.

Ocean Mechanical Energy

Ocean mechanical energy is quite different from ocean thermal energy. Even though the sun affects all ocean activity, tides are driven primarily by the gravitational pull of the moon, and waves are driven primarily by the winds. As a result, tides and waves are intermittent sources of energy, while ocean thermal energy is fairly constant. Also, unlike thermal energy, the electricity conversion of both tidal and wave energy usually involves mechanical devices. Because the OCS region begins beyond waters affected by tides, tidal energy generation is not considered in the OCS Alternative Energy Programmatic EIS. Ocean current energy is another form of ocean mechanical energy generated by the continuous movement of surface or near-surface waters, driven primarily by wind and by solar heating of the ocean water.

Other Offshore Energy Sources

Offshore wind and offshore solar energy do not rely directly on ocean waters as an energy source, although ocean water temperature differences affect ocean winds and cloud formation that would in turn affect these energy sources. Both energy sources can be and are currently used for power generation on land throughout the world. Their use in ocean regions such as the OCS is relatively new, although commercial offshore wind facilities are currently in operation in a number of countries outside the U.S. The application of these technologies to offshore use involves adapting them to a marine environment, which presents a number of technical and other challenges, but enables exploitation of the potentially enormous largely untapped energy source the ocean regions provide.

For More Information

The following presentation from the National Renewable Energy Laboratory also provides information on ocean-based renewable energy technologies. This presentation was shown at scoping meetings for the OCS Alternative Energy Programmatic EIS.

NREL Scoping Meeting Presentation: Renewable Energy Technologies for Use on the Outer Continental Shelf (3 MB)

Links to additional information on this topic are available on the Links page.