The United States has many potential sites where current generation could occur, and several projects are underway, including those in the East River in New York and the San Francisco Bay. Ocean tidal power harnesses the predictable cycle of energy produced by the tides. A tidal barrage works similarly to a large hydropower reservoir dam, but it is placed at the entrance to a bay or estuary.
The retained water in the bay is released through turbines in the barrage and generates power. A tide must have a large enough range between high and low tide, about ten feet, for the barrage to function economically. The best potential sites are located in northern Europe and the U.
West Coast. The potential environmental impact of barrages could be significant because they are built in delicate estuary ecosystems, but less intrusive designs such as fences or floating barges are under development. Tidal Current. Similar to river current technologies, turbines anchored to the ocean floor or suspended from a buoy in the path of an ocean current could be used to generate power. As wind moves over the surface of the ocean, it transfers energy to the water and creates waves.
Although variable in size and speed, waves are predictable and are constantly created. A variety of technologies are being tested to convert wave energy into electricity. Most systems capture energy on the surface of waves or use pressure differences just below the surface. These systems use the swells of waves to create pressure and move hydraulic pumps or pressurized air, which in turn puts generators into motion. The environmental impacts of wave generators are not fully known, but are thought to be minimal and site-specific.
The best potential sites for wave generation are ocean areas with strong wind currents. Hybrid wind and wave technology for offshore energy farms are in development.
Potential sites in the United States for hybrid wind-wave energy farms include the coastal areas of the East Coast and the Pacific Northwest. Ocean Thermal Energy Conversion. Currently spring , three wave power plants have permissions to test in Danish seas and one developer has permission to do pre-investigations to prepare an area for future wave energy plants. Skip to main content. You are here. Facts about wave power and hydropower. While it is certainly true that there are no direct greenhouse-gas emissions from hydroelectricity, broadening the use of hydro-power, particularly in heavily forested areas of the world, introduces other complex environmental and social impacts.
In fact, the reservoirs behind dams are major sources of methane a potent greenhouse gas , so hydro is not exactly a carbon-free source of energy. It was not until the s that hydroelectricity was born, with small hydropower dams in Michigan and Niagara Falls providing electricity to those places.
Skip to main content. How do we turn water into electricity?
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