The parallel is apt because Gorlov’s invention, which resembles a giant eggbeater, is a modified wind turbine that can convert 35 percent of water’s kinetic energy into electricity, regardless of which way the water is moving. This makes the technology well-suited to unidirectional rivers or tidal currents that change directions four times a day. It can do all this, Gorlov claims, without disturbing fish or boat traffic. The device, which has been tested in the Brazilian Amazon, the Cape Cod Canal, the Uldolmok Strait off of South Korea, and other sites, is now close to commercialization—part of a budding industry that aims to change hydropower as we know it.
While conventional hydropower provides about 7 percent of America’s electricity—and accounts for about 75 percent of the electricity supplied by renewable sources—prospects for future growth appear scant owing to the environmental toll of large dams. The U.S. Energy Department estimates that “free-flow” hydro technologies could supply 15,000 megawatts of generating capacity (comparable to 15 large nuclear plants), but Gorlov considers the potential much greater. Worldwide, he says, “more than 90 percent of the energy in moving water is in sites where you can’t build dams”—places like rivers with low-grade currents, tidal estuaries, and ocean currents in general. Tapping into the water flowing beneath the Golden Gate Bridge, for example, could yield two times more electricity than San Francisco’s peak demand.
In 2003, a 300-kilowatt turbine installed in a Norwegian strait became the first free-flow hydro system to deliver electricity to a power grid. Also in 2003, a “watermill” of similar capacity began operating in a tidal channel a mile offshore from Lynmouth, England. Since then, prototypes have been placed in New York’s East River, Nova Scotia, and other sites.
Meanwhile, plans are being laid for America’s biggest river, the Mississippi. Texas-based Hydro Green Energy now has two turbines mounted from a barge in Hastings, Minnesota, continuously feeding 70 kilowatts into the power grid. Hydro Green is investigating other spots along the Mississippi, as is Free Flow Power of Massachusetts, which has secured federal permits to explore 50 different sites. Ultimately, Free Flow president Dan Irvin envisions 200,000 turbines spread along the length of the river, generating 2,000 megawatts. All without approximately impacting river flow.