MARINE & HYDROKINETIC ENERGY

What’s this? Using advanced technology to capture energy from the waves and currents of oceans and rivers

Sources Capturing the energy contained in near and off-shore waves is thought to have the greatest energy production potential researchers believe that ocean tides hold promise as an energy resource Other stream resource prospects for hydrokinetic energy development include ocean currents, such as the Gulf Stream, which result from winds and equatorial solar heating; free-flowing rivers, from which energy capture is possible without any intrusive dams; and even constructed waterways, such as irrigation canals

Equipment used Oscillating Water Column: Waves enter and exit a partially submerged collector from below, causing the water column inside the collector to rise and fall. The changing water level acts like a piston as it drives air that is trapped in the device above the water into a turbine, producing electricity via a coupled generator

Point Absorber: Utilizes wave energy from all directions at a single point by using the vertical motion of waves to act as a pump that pressurizes seawater or an internal fluid, which drives a turbine * One configuration, called a hose pump point absorber, consists of a surface-floating buoy anchored to the sea floor, with the turbine device as part of the vertical connection. The wave-induced vertical motion of the buoy causes the connection to expand and contract, producing the necessary pumping action

Attenuator: Also known as heave-surge devices, these long, jointed floating structures are aligned parallel to the wave direction and generate electricity by riding the waves. The device, anchored at each end, utilizes passing waves to set each section into rotational motion

Overtopping Device: creates a reservoir : a head of water—a water level higher than that of the surrounding ocean surface—which generates the pressure necessary to turn a hydro turbine as the water flows out the bottom of the device, back into the sea

Efficiency & cost Estimates suggest that the amount of energy that could feasibly be captured from U.S. waves, tides and river currents is enough to power over 67 million homes Based on current project proposals, experts predict that the country could be producing 13,000 MW of power from hydrokinetic energy by 2025 # A 2005 report by the Electric Power Research Institute (EPRI) estimated that some U.S. utility-scale wave power projects could produce electricity for about 10 cents per kilowatt-hour (kWh) once the technology has matured # Each device costs about $170K and produce a minimum of 500 Kw and annual maintenance is $29K per operation

Consumption/Usage With more than 50% of the population living within 50 miles of coastlines, there is vast potential to provide clean, renewable electricity to communities and cities across the United States using marine and hydrokinetic technologies Hydrokinetic energy can be used as a replacement for other energy resources The technical resource potential for electric generation from ocean thermal resources is estimated at 576 TWh/year in U.S. coastal waters (including all 50 states, Puerto Rico, and the Virgin Islands) technically recoverable resource for electric generation from waves is approximately 1,170 terawatt-hours per year (TWh/year), which is almost one third of the 4,000 TWh of electricity uses in the United States each year The world’s first commercial wave farm was built offshore of Portugal, and operated for just two months before mechanical problems and financial troubles halted the project

Advantages If the development of 13,000 MW of power from hydrokinetic energy by 2025, as estimated by environmentalists, occurs it will displace 22 new dirty coal fired power plants *avoiding the annual emission of nearly 86 million metric tons of carbon dioxide, as well as other harmful pollutants like mercury and particulate matter. The avoided carbon emissions in 2025 would be equivalent to taking 15.6 million cars off the road

Disadvantages The main disadvantages are that river based energy systems do not provide a constant enough flow of energy while ocean based energy systems can have undesirable affects on mammals, fish migration and the general marine eco-system

Ecological Problems Alteration of current and wave strengths and directions Alteration of substrates and sediment transport and deposition Alteration of habitats for benthic organisms Generation of electromagnetic fields (EMF) Toxicity of paints, lubricants, and antifouling coatings Interference with animal movements and migrations, including entanglement In the case of ocean thermal energy conversion technologies, additional potential effects stem from the intake and discharge of large volumes of sea water; changes in temperatures, nutrients, dissolved gases, and other water quality parameters

Bibliography http://www.hydro.org/tech-and-policy/faq/ http://hydrovolts.com/2011/10/26/what-about-hydrokinetic-power/ http://www.hydro.org/tech-and-policy/technology/marine-and-hydrokinetic/ http://www.c2es.org/technology/factsheet/Hydrokinetic http://www.ferc.gov/industries/hydropower/gen-info/licensing/hydrokinetics.asp https://www.asme.org/engineering-topics/articles/renewable-energy/hydrokinetics-comes-to-the-forefront http://earthtechling.com/tag/hydrokinetic-energy/