| For more than 200 years inventors worldwide have | | | | 3. PowerBuoy "Like the AquaBuOY above, the |
| filed patents for wave-power technology of a dazzling | | | | PowerBuoy resembles a navigational buoy, although |
| variety of designs-bobbing objects ("ducks"), buoys, | | | | one with long cylinder extending far below that houses |
| articulated rafts, floating bags, overspills, and many | | | | the mechanics of the system. These PowerBuoys |
| others. There has been no shortage of ideas. Many of | | | | (Ocean Power Technologies) are placed from one to |
| these ideas are in fact technically feasible, so it seems | | | | five miles offshore in 100 to 200 feet of water, and |
| a shame that this renewable energy resource has not | | | | can be ganged together to form a "wave-power |
| been much used. The main challenge is building a | | | | farm" such as the one to be installed off the coast of |
| system that is economically attractive when so many | | | | Santo, Spain. That 1.39MW station will have one 40kW |
| other forms of energy production (nuclear, fossil fuels) | | | | and nine 150kW PowerBuoys. |
| receive subsidies and already have infrastructure in | | | | OFFSHORE: ATTENUATOR SYSTEMS |
| place. There are some wave power systems in place | | | | 1. Pelamis - Ocean Power Delivery, Ltd., developed |
| around the globe: the Faroe Islands; Islay, Scotland; | | | | world's first commercial offshore wave-power facility |
| Oahu, Hawaii (providing power for the U.S. Marine | | | | using its Pelamis Wave Energy Converter, a string of |
| Corps. base there); Santo, Spain; Portugal; and even | | | | steel cyclinders hinged to articulate. It lies |
| the world's first commercial "wave farm" in England. | | | | half-submerged, like a 150-meter-long, bright red sea |
| The World Energy Council has estimated that wave | | | | snake (pelamis is the genus for the sea snake), more |
| power could produce as much energy in a year as | | | | or less facing into the waves. The cylinders contain |
| 2,000 oil, gas, coal and nuclear power plants' twice the | | | | hydraulic pumps activated by the wave action; the |
| amount of electricity produced worldwide-by | | | | electricity comes as high-pressure oil gets pumped into |
| generating as much as 2 terawatts (that's 1 trillion | | | | generators. The first phase of the wave farm, located |
| watts). | | | | 5 km off the coast of Portugal, comprises three |
| Not every place is a candidate for wave power | | | | 750kW Pelamis "snakes" that combined to generate |
| generation. Prime locations identified are Scotland, | | | | 2.25 MW; another 28 are expected to be added, |
| northern Canada, southern Africa, and the Atlantic | | | | bringing the total power generated to 22.5 MW'enough |
| Northeast and Pacific Northwest of the United States. | | | | to provide electricity for more than 15,000 homes. |
| Experts have estimated that wave-power systems in | | | | OFFSHORE: TERMINATOR SYSTEMS |
| the Pacific Northwest alone could generate up to 70 | | | | 1. Nearshore OWC-This is an offshore version of the |
| kW per meter of coastline. | | | | Limpet, described below. |
| Typical Designs | | | | OFFSHORE: OVERTOPPING SYSTEMS |
| Wave-power systems can be located onshore or | | | | 1. Wave Dragon-Overtopping systems work very |
| offshore, and come in a surprising range of designs. | | | | much like hydroelectric dams, using the potential |
| There are currently four basic "capture" methods: point | | | | energy of water stored at an elevation higher than the |
| absorbers (largely vertical, with a relatively small | | | | turbines it drives. The Wave Dragon overtopping |
| footprint on the surface); attenuators (horizontal | | | | system funnels the waves into its own reservoir to |
| footprint, arranged parallel to the waves to undulate | | | | create a head; the water is then released through |
| with the flow); terminators (perpendicular to the | | | | channels that contain turbines. The Wave Dragon is |
| waves); and overtopping (perpendicular to the waves, | | | | moored 25 to 40 meters offshore in deep water, |
| which break over the system). There are different | | | | somewhat like a floating beach. |
| power take-off systems including hydraulic ram (water | | | | ONSHORE: OSCILLATING WATER COLUMN: |
| hammer pumps water above the starting point); | | | | 1. Limpet (Land Installed Marine Powered Energy |
| elastomeric hose pump (peristaltic, like your intestinal | | | | Transformer)- This an oscillating water column (OWC) |
| tract), pump-to-shore, hydroelectric turbine, air turbine, | | | | system to convert the waves' kinetic energy to |
| and linear electrical generator. Here are some systems | | | | electrical power. Picture a box with the open end |
| already in operation, or close to it: | | | | submerged but slightly tilted toward the incoming |
| OFFSHORE: POINT ABSORBER SYSTEMS | | | | waves, with air trapped inside the box. Now imagine |
| 1. The Salter "Duck"-In 1970 Stephen Salter ("the father | | | | there is a narrow outlet for this air, and inside this tube |
| of wave power"), a professor at the University of | | | | is a turbine. As the waves raise the level of the water |
| Edinburgh, designed a wave-power device that could | | | | inside the box, the air rushing in and out of the tube |
| both stop 90 percent of the wave motion and convert | | | | powers the turbine. A Limpet system (WaveGen) in |
| 90 percent of that into electricity, a standard that all | | | | Islay, Scotland, uses an inclined oscillating water column |
| other designed continue to be measured against. | | | | (OWC) system optimized for the area's anverage |
| Ironically, the Duck itself never went into use. During the | | | | annial wave intensity, and feeds a pair of 250kW |
| 1990s, a project based on the Duck and dubbed the | | | | generators. The Limpet power station in the Faroes is |
| OSPREY (Ocean Swell Powered Renewable | | | | very similar. WaveGen also designs a near-shore |
| Energy), commenced in the Clyde Estuary of the | | | | oscillating water-column system. |
| Scottish coast. Capable of generating 1 mW of power, | | | | There are many companies designing wave-power |
| the OSPREY was on its way to becoming an | | | | systems using these and other designs (such as the |
| unqualified success until Hurricane Felix came along | | | | tapered channel system, an onshore system, and the |
| and sunk it (at great expense in terms of both money | | | | pedulor system, an offshore device), and new ones |
| and confidence). | | | | seem to come along frequently as more countries |
| 2. The AquaBuOY wave energy device-AquaBuOYs | | | | come to recognize the potential of wave power. |
| (Finivera Renewables) really do look like navigational | | | | Wave Power Advantages |
| buoys, and this is no coincidence. Obviously, maximum | | | | 1. Wave energy is an abundant and renewable |
| output from a wave-power device should be during | | | | resource. |
| those times when the waves are at their highest, but if | | | | 2. Even though not every country has coastline, the |
| the technology can't withstand rough seas (as with the | | | | combined potential output of wave-power generation |
| OSPREY, above), they aren't much good. Operating | | | | would meet all the electricity needs of the world. |
| on the premise that since navigational buoys can | | | | 3. Although the equipment represents a substantial |
| survive for decades in all sorts of conditions, the | | | | investment, the "fuel" is free and not confined by |
| AquaBuOYs were designed to ride the waves for an | | | | geopolitical boundaries. |
| estimated 100 years. The vertical wave action drives a | | | | 4. The effect on the environment is deemed to be |
| two-stroke hose pump that directs pressurized | | | | minimal. |
| seawater into a turbine connected to a generator; the | | | | Wave Power Disadvantages |
| resulting power is sent via an underwater transmission | | | | 1. These are most effective near coastlines, of which |
| line. While at least four projects are in the permitting | | | | there is a finite supply. |
| process (including one in Makah Bay, WA), as of this | | | | 2. Large scale systems are still in the early stages. |
| writing. | | | | |