These are just the four basic designs I could find that harness wave power today. They are beginning to grab headlines, and have demonstrated themselves as excellent choices for sustainable energy. I find the design element inherent in harnessing wave power an exciting example of how design plays an important role in sustainable energy technology.::[by T. McGee]
Sustainable alternative energy is becoming attractive as oil costs rise and the negative side effects of traditional energy systems begin to become apparent. One often overlooked, but rapidly growing alternative is wave power. There are fascinating new designs for harnessing the power of the wave. I found four significant technologies, all of which are in their first steps of operation and succeeding wildly.
The oldest design I found is the Limpet (Land Installed Marine Powered Energy Transformer) by Wavegen and is located on the island of Islay, off Scotland’s west coast. This bugger might not be the prettiest of the bunch, but it’s much better to look at then the smog here in L.A. The Limpet design takes the wave into a funnel and drives air pressure past two turbines, each of which turns a 250 kW generator. The clever part of this design is that it takes the wet works out of the engineering solution. By placing all moving parts and generators above the sea swell, they mechanics stay in an easy location for maintenance. I think the biggest down side to this design is that it might be noisy to neighbors, and I’m not sure I would want to look at it on my beach- maybe a little paint job would change my mind.
A different approach is to place wave collection devices where there would normally be an ocean break or sea wall anyway. WaveEnergy of Ålgård Norway has, what I think, is one of the most esthetically appealing designs for harnessing energy (and don’t we all want good design in our energy production facilities?). The ingenious design plays a critical role in manufacturing the energy. By creating a series of layered ‘reservoirs’ up a carefully calculated slope, they have essentially digitized the potential energy of wave input. This is then converted to kinetic energy (by falling down), and this turns the turbine/generator. They do not currently have a facility up and running (the design is only a year old) but they estimate that their 500m breakwater can mount a respectable 150 kW generator capacity. Not too shabby for a breakwater. WaveEnergy also has creative plans for re-using old deep sea oil platforms (talk about reuse and recycle). The oil rigs are perfect, primarily because they are already in rough seas and have electrical and pipelines (say for hydrogen?) back to the mainland. WaveEnergy began their pilot program this January; I’m excited to see their progress in the next few months.
The third approach is perhaps my favorite; the buoy technology. Ocean Power Technologies from New Jersey has a great website describing why ocean power has significant advantages over other energy generation, including wind and solar (I think all have their place). Their PowerBuoy system is impressive. They estimate that a 10 Megawatt PowerBuoy station would only occupy 4 acres of open ocean (how large is a coal plant, and roads, and mine?). Also, they estimate that a 100 Megawatt PowerBuoy Station would cost LESS then fossil fuels. That is only 40 acres of open ocean (not that much) and you have a technology which is cheaper then oil, and sustainable. One of the best things about this technology is it is simple. It is a buoy. It moves up and down, and that motion creates an electrical charge which is turned into DC and sent to the shore. The minimal size and placement of the buoy is also a plus, as it has a low environmental, and social impact. The buoy is not readily visible from land, and it can even act to attract fish and create an artificial reef. This technology has been around for at least 3 years, and several companies are working on buoy –type devices. I see this one as ready for installation in my neck of the woods.
Lastly there is another buoy system, but this one was so different it needed its own section. Ocean Power Delivery LTD from Edinburgh has developed a long buoy dubbed the ‘Pelamis’ that takes advantage of the swell of a wave. The swell is the broad rolling waves that tend to make me sick at sea. Basically, the Pelamis is made of large semi-submerged sections, like a submarine cut into pieces, and the wave action makes the Pelamis bend between the sections. This bending action forces hydraulic pistons to move in the device and push fluid around generating a linear flow, which they take advantage of to produce energy. The website does it more justification then I can. They estimate that a 1 sq kilometer farm could produce 30 Megawatts. The advantage of this system is that it could easily be deployed as a deep ocean farm, and take advantage of sea swell anywhere.