SOLUTIONS
Tidal Energy
Tidal power can provide very significant inputs to the electricity grid. In the U.K., a proposed 10-mile tidal barrage across the Severn estuary exemplifies this technology. The Severn Barrage would contain over 200 turbines (each 40MW), generating a huge 8.6GW during flow (average power 2000MW). Arrays of sluices let the tide in and then close, forcing water out through the turbines after the tide has retreated some distance beyond the barrage. This practice increases turbine efficiency. The Severn Barrage would generate 17 million kWh (kilowatt hours) annually; 6% of total UK electricity demand. It would displace 18 million tons of coal, or 3 nuclear reactors. It would also provide flood protection to the coastal areas of the Severn Estuary.
Wave Power
Ocean waves contain a large amount of power: a global market for wave power could spare the release of 1B tons of carbon gas annually. One of the best-tested technologies to date is an Australian system, Oceanlinx. Each 330-ton platform rises from the sea floor to 23ft above sea level and generates 1.5MW. It makes use of the oscillating water column within an ‘OWC’—a chamber open beneath the waterline, moving on fixed stilts and adjusting itself with the tide. As the waves move up and down, they force air in and out of a bidirectional-airflow turbine. The turbine is housed at the narrowest point of the OWC, driving the electricity generator. Multiple units (see above illustration) would produce 20MW or more per wave-farm. This company currently has 6 projects, located in Australia, the U.S., U.K. and S. Africa.