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Thursday, 2 February 2012

A Wave Power Generator with a Twist: It Generates Electricity On Dry Land

A relatively new* type of reciprocating wave-powered electricity generator called Searaser has been developed and is moving forward. Searaser, acquired by Ecotricity, is not a typical wave power plant.
The first peculiarity is that it does not generate electricity out at sea. Due to the fact that waves move up and down in the ocean, they can continuously move a float attached to a reciprocating pump that can pump water through a water-powered onshore electricity generator for the sake of keeping the electrical parts of the system out of the water.
As Damian Carrington of The Guardian notes, its is a bit like an aquatic “bicycle pump.”

Searaser Skips the Challenges of Ocean- or Sea-Based Electricity

“If you put any device in the sea, it will get engulfed in storms, so it all has to be totally sealed,” the inventor, Alvin Smith, says. ”Water and electricity don’t mix – and sea water is particularly corrosive – so most other devices are very expensive to manufacture and maintain.”
Ecotricity founder, Dale Vince, claims: “We believe Searaser has the potential to produce electricity at a lower cost than any other type energy, not just other forms of renewable energy but all ‘conventional’ forms of energy too.”
A prototype of the Searaser has already been tested successfully.

Where the Idea for Searaser Came From

Smith’s Searaser idea has fun but simple origins, as so many great technologies do. “The idea of Searaser came to Smith when he was playing with a ball in his swimming pool and felt the energy released when the ball bobbed to the surface,” Carrington writes. “He said the device has the advantages of being extremely simple – like a bicycle pump – contains no lubricating or hydraulic oil, and is not a rigid structure and so can go with the flow in heavy seas.”
Another benefit of the system is that the energy produced could be stored in reservoirs and released for later use, helpful given the increasing amount of intermittent renewable energy going on the grid.
Wave-powered generators are a member of the family of hydroelectric power plants, which all use the movement of water to generate electricity. But it’s obviously a bit different than the hydroelectric power technologies you’re used to, isn’t it?

Wave power: worth another look. And another, and another…

Much like nuclear fusion, wave power always seems to be at least ten years away.
The basic idea of using ocean waves to produce electricity may be simple, but the execution isn’t. The sea has a tendency to thrash the devices we stick in it, including tethered buoys that generate electricity as they bob up and down.
But a study released Thursday by the U.S. Department of Energy suggests wave power remains a dream worth pursuing. Especially in California.
Wave power devices stationed along California’s long coastline could generate up to 166 terawatt hours of electricity per year, according to the study, if those devices were placed in the water above the outer continental shelf. Wave power buoys would generate a little less, about 129 terawatt hours, if stationed above the inner continental shelf, in waters no more than 50 meters deep.
For comparison, the United States as a whole uses 4,000 terawatt hours of electricity each year, according to the Energy Department. The California Independent System Operator, which manages the electricity grid for 80 percent of California, says its territory uses about 225 terawatt hours per year.
“The takeaway message here is, it is a resource worth considering and worth doing more work on,” said Hoyt Battey, with the Energy Department’s water power program. “For the West Coast in particular — for those states — it could be a significant contribution.”
Tidal power too could benefit the state, although not to the same degree.
A related study released by the Energy Department on Thursday looked at the energy-generating potential of harnessing ocean tides at key “hotspots” across the United States, including the Bay Area’s Golden Gate. Using underwater turbines to tap the Gate’s strong tidal currents was a pet project of former Mayor Gavin Newsom. It went nowhere.
The Energy Department estimates that Golden Gate tides could generate a maximum of 178 megawatts of energy. A megawatt is a snapshot figure, roughly equal to the amount of electricity used by 750 typical homes at any given moment.
While it isn’t trivial, 178 megawatts is far less electricity than many of the large solar power plants under construction in California will be able to generate.  It also pales in comparison to the 18,239 megawatts of tidal power that Alaska’s Cook Inlet could produce, according to the Energy Department study.
“What we have heard from developers and experts who’ve looked at the Golden Gate is it’s somewhat marginal — on the fence — in terms of development,” Battey said. “That’s not to say it couldn’t be developed at some point.”