Q: I’ve heard of buoys that convert waves into electric energy. Why is your concept better?A: Buoys or “point absorbers” are easy to understand, but not very efficient. They radiate away most of the wave energy that reaches them from the sea, absorbing only about 25% of an incoming wave. Once they’ve converted that energy to electricity and transferred it to the grid, only about 10% of the original wave energy is converted into kilowatts to power your home. Buoys are excellent for providing low power amounts to isolated beacons, communication devices, etc., but are not economically scalable to megawatt utility designs. The Atargis cycloidal wave energy converter is expected to convert about 65% of an incoming wave into useful electric energy. This means Atargis devices will require less ocean area and will be much less expensive to buy and operate.
Q: How does the Atargis wave energy converter survive storms?A: By using a simple sea floor mounting, the Atargis CycWEC can be raised out of the water for installation and maintenance, lowered into power production mode just below the surface, and lowered below the energetic waves (typically the top 3 meters or 10 feet) of a storm. By contrast, line-moored heaving buoys, point absorbers and wave attenuators cannot escape the storm’s fury, so they must be over-engineered to survive the high loads. Floating overtopping turbines and oscillating water columns face the same challenge, as do shore-mounted devices.
Q: What effect will the Atargis wave energy converter have on the marine environment?A: The effects of rotating hydrofoils on fish and marine mammals appear to be negligible—marine biologists we’ve spoken with think that fish and marine mammals see and avoid hydrofoils, as the speed of hydrofoil rotations is relatively slow even at maximum energy output. Subsurface supports tend to naturally encourage the formation of artificial reefs and fish attraction zones, which generally is beneficial to the local marine environment. Unlike solar cells, wave energy converters don’t require a lot of energy in production, nor do they require exotic materials. Wave power (electricity) is pollution-free during use.
Q: What’s the difference between wave energy converters and tidal or river turbines?Most simply, the two are different environments requiring different technologies to produce electricity. The tidal turbine can only extract energy from a constant fluid flow, which reverses every half day. If you put a tidal turbine into a wave environment with no current, it would extract no energy at all. Conversely, if you installed a wave device in a tidal flow, it wouldn’t work very well either. The “flow” underneath a wave changes direction with each wave passage. Tidal turbines would rock back and forth in waves, but would not spin and would not produce power. Tidal turbines are best located well below the surface (because the waves, when present, would upset their operation). On the other hand, wave energy converters need to operate near the water surface, where waves are most energetic.
Wave energy converters can be designed to work in any wave environment, but work best where ocean wave energy is moderate to strong, including thousands of miles of coastline in the US. The best locations tend to be on the west coasts of continents, between 40 and 60 degrees latitude. Tidal turbines are limited to areas of strong tidal flow (in North America, that’s limited to the East River in NYC, the Bay of Fundy in Canada, Race Rocks at Vancouver Island in Canada, and Tiburon Island off Baja Mexico). The total tidal power that can be usefully tapped in the world is estimated to be only about 90 GW. The useful global ocean wave resource is 50 to 100 times larger.