BOBBING FOR ENERGY: SOLAR POWER THAT FLOATS
By Don Willmott
In densely populated areas of the world, land is valuable. So if you’re looking to build a massive solar energy farm, why not float it offshore? It’s happening today at the southern tip of Japan, where the 290,000 solar panels of the Kagoshima Nanatsujima Mega Solar Power Plant went online to much fanfare and ribbon cutting last November. You can understand why Japanese citizens would be excited. Any viable alternative to nuclear power is certainly a welcome development for the disaster-plagued nation these days. As for that active volcano in the distance… no worries, so they say.
The 1.3 million square-meter Kagoshima solar array, which developer Kyocera equates to the size of 27 (Japanese) baseball stadiums, is now Japan’s largest array, and will generate 79 megawatts of energy annually. That’s enough, the company claims, to power 22,000 homes and offset 25,000 tons of CO2 per year. The cost of the yearlong construction project: $275 million.
The plant was made economically viable by a “feed-in tariff,” a long-term government contract that guarantees a subsidy on the cost of the relatively expensive energy the plant generates by forcing utilities to buy the energy at fixed prices. Used in dozens of countries around the world, such tariffs have been credited with spurring the creation of more solar plants, especially in Japan, where the 2012 tariff program was created in direct response to the Fukushima nuclear disaster. In fact, The Washington Post reported in June that Japan’s solar output will double this year. Even Lawson, a major Japanese convenience store chain, is putting solar panels on several thousand of its rooftops.
Next up is the southwestern state of Kerala, India, where plans are in place for a $70 million, 50-megawatt floating solar plant similar in size to Kagoshima Nanatsujima. Local power company NHPC, which can also take advantage of a feed-in tariff, will begin with a pilot project focusing on 3,000 square-foot arrays that generate about 100 kilowatts. These relatively small floating systems that can be deployed in many locations, including on top of canals.
What about the fish that live below the surface? "The ecology of the water body is not likely to be affected much, and it will also reduce evaporation, thus helping preserve water levels during extreme summer,” said SP Gon Choudhury, chairman of the Renewable Energy College, in a statement. “Solar panels installed on land face reduction of yield as the ground heats up. When such panels are installed on a floating platform, the heating problem is solved to a great extent," So the effect is “not much,” which may mean that a bit more research is needed.
And for the ultimate in marine solar collection, there’s always the giant floating duck option. Over in the alternative energy paradise of Denmark, a sustainable design contest yielded the idea of a 12-story-high rubber duck-shaped solar array that would float around Copenhagen harbor collecting solar energy. Not only would the big shiny tub toy generate electricity, it could also serve as a tourist attraction and floating museum of carbon neutrality. The duck’s designers say it’s also scalable, so you could have a smaller model for your backyard pool, which would be just… ducky.
Don Willmott is a New York-based journalist who writes about technology, travel, and the environment for a wide variety of publications and websites.