There is a land rush to build solar power plants. In the U.S., solar leases under review by the Department of Interior cover 1.8 million acres in the West alone. Globally, solar photovoltaic (PV) capacity has been doubling, with another 16 gigawatts of power added in 2010.
Yet a vast neglected swath of prime real estate is still wide open: the water. Reservoirs, lakes, retention ponds, and other calm bodies of water are being targeted as the new frontier for floating solar power plants. A handful of companies are building pilot projects to prove the concept at scale from India to Napa Valley in California.
One of the most ambitious will float on Lake Neuchâtel in Switzerland later this year. Solar developer Nolaris plans to launch three solar-powered "islands," 82 feet in diameter, with the Swiss energy company Viteos. The floating plastic and steel platforms support an array of 100 photovoltaic (PV) cells that will rotate with the sun, potentially laying the groundwork for a scaleable technology. (Nolaris is also promoting concentrating solar lenses to generate 482ºF steam to drive a turbine.)
Other companies pursuing this concept are favoring floating pontoons with individual photovoltaic (PV) assemblies on the water’s surface. Concentrating lenses focus the sunlight on a PV cell (or steam-generating circuit), while a simple motor, light sensors, and software rotate to maximize power generation. During a storm, common in tropical climates where many pilot projects are planned, the entire array can submerge as the winds rise.
In some places, floating solar power’s potential promises to rival its land-based counterparts, especially where land is expensive. Sunengy, an Australian company specializing in what it calls Liquid Solar Array technology, says its arrays could match the power output of a typical hydroelectric dam by covering less than 10% of the reservoir’s surface. Sunengy is now teaming up with Tata Power, a subsidiary of the Indian giant Tata Group, to build India’s first floating solar power plant. Sunengy estimates if India used just 1% of its 11,500 square kilometers of captured water it could generate the equivalent to 15 large coal-fired power stations.