Generating Renewable Energy from the Ocean
Will Wave, Tidal Generators Change the Future of Electric Power?
Jun 5, 2009
Power is currently being harvested from the ocean in two different ways:
- Wave generators create electricity from the movement of ocean waves, which are caused by wind moving across the sea.
- Tidal generators generate power from the regular in-and-out flows of ocean tides, which are caused by the gravitational pull of the moon and sun.
The electric generating potential of the ocean is enormous: up to 3 terawatts a year from ocean waves, and 0.8 terawatts from tidal flows, according to a 2005 study (Tester, Jefferson W.; et al. (2005), Sustainable Energy: Choosing Among Options, The MIT Press, ISBN 0-252-20153-4.)
Advantages of Tidal and Wave Generators
Today’s most promising water-based generators operate something like floating wind turbines anchored to the sea floor. Moving ocean water creates pressure that turns a hydraulic turbine, which in turn is linked to a generator that converts the hydraulic energy into electricity.
Ocean-powered generators have important advantages over both conventional forms of power and other renewable energy alternatives, such as wind and solar power. Ocean-generated energy is:
- Clean. Unlike coal, oil, or nuclear energy, the electricity produced by tidal or wave generators is emission-free. Powering houses with ocean-generated electricity could potentially save millions of tons of carbon emissions each year.
- Unobtrusive. Ocean-borne generators ride the waves without protruding above the water’s surface, so they don’t obstruct views the way today’s huge wind turbines can.
- Consistent. Waves and tidal movements are predictable and occur all year round, so ocean generators aren’t affected by clouds or seasonal changes as solar collectors are.
Moving from Experimental Technology to Commercial Reality
Wave and tidal generators are currently in advanced phases of testing or initial commercial operation in several locations around the world. A tidal current generator developed by Sea Generation Ltd. began operating in Northern Ireland’s Strangford Lough in June, 2007, with a potential capacity of 1.2 megawatts. A wave farm consisting of three generators built by Pelamis Wave Power opened off Portugal in September, 2008. Operating at full capacity, the farm can generate enough electricity to power more than 1,500 houses. Both of those projects, though, have been dogged by technical problems caused by the harsh ocean environment.
British company Checkmate Seaenergy developed a new, simpler generator, the Anaconda Wave Energy Converter, to help combat breakdowns caused by the corrosive effects of seawater. While the Seagen and Pelamis turbines are primarily made of metal, the Anaconda is made mainly from fabric and rubber.
A small-scale Anaconda generator has just completed testing in a tank in Hampshire, England. If the tests prove successful, larger versions of the power generator will be tested in the ocean. Checkmate Seaenergy, the Anaconda’s maker, hopes to have wave generators in commercial production by 2014.
Future Prospects for Renewable Energy from the Ocean
Many governments have set ambitious targets for generating electricity from renewable sources. The European Union plans to generate 20% of its electricity from renewables by the year 2020. The United States recently set a target of generating 25% of all electricity renewably by 2025.
As with many new technologies, getting the funding to overcome technical problems and test new installations is one of the major obstacles standing between ocean-power generation and commercial success. Even in a difficult economic climate, the new water-powered generators are promising enough that governments and private companies are pressing ahead with plans to generate a small but significant part of their electricity needs from the ocean.
See more innovative ideas for alternative energy:
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