Underwater Turbines to Capture Energy of Moving Water (USA)

As the U.S. slowly abandons its dams, more and more pilot programs pop up for deriving power from tides and river currents. Welcome to a new age of water power.

Every day, enough water flows down America’s rivers and streams to power tens of millions of homes. With the era of big dams effectively over in the U.S., halted by the lack of suitable sites as much as environmental concerns, the time for hydrokinetic energy may just be dawning.

The ideas of using turbines, or other mechanical devices, to capture the energy of moving water is not a new one. Yet the technology for such hydrokinetic energy has met serious resistance from conditions below the surface. As water is 832 times denser than air, it poses tough engineering challenges for power generators who must contend with corrosion, stray electromagnetic fields, and rules to safeguard sealife.

“There’s a lot of electricity to be had from these device and probably fewer environmental impacts”, says Glenn Cada, senior researcher at Oak Ridge National Laboratory, in the Department of Energy’s program to improve hydrokenetic technology and minimize the environmental impacts. “It’s not as easy as taking a taking a wind turbine and putting it under water. The forces are much greater. We are trying to understand how to make them sturdy enough to generate electricity from river currents.”

Demonstration projects in the Mississippi and New York’s East Rivers have been steadily perfecting the technology needed to capture this energy for almost a decade. Verdant Power’s Roosevelt Island Tidal Energy project in New York’s East River (soon to be expanded) has successfully operated six underwater turbines between 2006-2008, and delivering 70 megawatt hours to a nearby supermarket and parking garage in what the company called the “world’s first grid-connected array of tidal turbines.” Free Flow Power Power has installed its own turbines, resembling jet engines, in the Mississippi and is eying more than 50 expansion sites.

Now, everyone from state agencies to universities are racing to get into the game. Applications to the Federal Energy Regulatory Commission for new hydrokinetic sites have soared in the last three years: 79 have been approved since 2009 (almost double those as of 2008), and 145 more are awaiting final approval in Missouri, Maine, Louisiana, New Jersey and other states.

Eventually, based on the ambitiions of several energy developers, underwater fields of hundreds of turbines could generating enough megawatts to power cities around the country.

“We’re trying to prove these things right now,” says Cada.

by Michael J. Coren (fastcompany)

[mappress]

Source: , July 22, 2011;