Ocean Energy and Hydropower Kimberly Hill ME 3322 Thermodynamics

Ocean Energy and Hydropower Wave Energy Kinetic energy from wave movement of water can be used to power a turbine. The wave rises into a chamber. The rising water forces the air out of the chamber. The moving air spins a turbine which can turn a generator. When the wave goes down, air flows through the turbine and back into the chamber through doors that are normally closed. Another method is to actually use the up and down motion of the wave to power a piston that moves up and down inside a cylinder. That piston can also turn a generator.

Ocean Energy and Hydropower Tidal Energy This technology has been in use since the 11th Century. When tides come into the shore, they can be trapped in reservoirs behind dams. Then when the tide drops, the water behind the dam can be let out just like in a regular hydroelectric power plant. An increase of at least 16 feet between low tide to high tide is needed for optimal performance. A facility using this technology is called the La Rance Station in France.

Ocean Energy and Hydropower Ocean Thermal Energy Conversion (OTEC) Using the temperature of water to make energy actually dates back to 1881 when a French Engineer named Jacques D'Arsonval first thought of OTEC. Sunlight warms the surface water, but below the surface, the ocean gets very cold. A difference of at least 38 degrees Fahrenheit is needed between the warmer surface water and the colder deep ocean water. All systems require a large-diameter intake pipe to pump cold water to the surface. Closed-cycle OTEC systems Open-cycle OTEC systems Hybrid OTEC systems

Benefits and Drawbacks Resources are widely available. They supply power continuously, rather than intermittently like solar and wind generation. Reduce dependence on fuels-including oil, coal, and natural gas. Ocean energy is also not subject to fuel cost increases, positioning it as a potential hedge against price volatility. These technologies will not emit any of the pollutants that can be extremely harmful to wildlife populations, and they will not contribute to climate change, which is already altering habitats worldwide. Do not irrevocably alter natural water flows and habitats. Ocean Energy and Hydropower Corrosion and fouling problems, access limitations, and storm potential. For systems installed in deepwater environments, significant technology gaps must be overcome in the areas of underwater cabling, grid connection, and energy storage. Limited number of suitable locations. Wildlife colliding with spinning turbines or other structures may be injured or killed. OTEC systems transport large amounts of deep ocean water to the surface. Discharge points could create localized changes in water temperature and chemistry. Positive Negative

Hydropower Similar to ocean energy technologies (waters other than oceans) Utilize moving water (in one direction) Incorporate turbines that spin when in contact with moving water, as well as generators that transform this rotational energy into electricity. These components are installed in or adjacent to dams and diversion structures that take advantage of gravity as water flows or cascades downward. Hydropower is most often used as a commercial electric technology and occasionally can be used to power existing mill sites that are being renovated for commercial, industrial, or even residential use. Ocean Energy and Hydropower

Benefits and Drawbacks Ocean Energy and Hydropower Flowing water carries much more energy than the moving air used in wind power because water is much denser than air. Abundant, domestically available option for generating clean energy Facilities last a long time No fuel cost Low Maintenance Continuous Operation Output can be controlled to keep pace with energy demands Environmentally responsible technology Positive Negative Expensive to build Dependent on precipitation Impacts ecosystems due to dams and diversions Disturb natural watercourses Impacts local fishing industries Animals can be killed if they become trapped in flows through turbines.

Sources cean.htmlhttp:// cean.html htmhttp:// htm gifhttp://library.thinkquest.org/15215/media/hydroelectric_dam. gif state.edu/jbox/photos/2004_Norway/IMG_0578_hydropower_s m.jpghttp://polarmet.mps.ohio- state.edu/jbox/photos/2004_Norway/IMG_0578_hydropower_s m.jpg Ocean Energy and Hydropower