By Steve Brown
Burt Hamner has a simple idea: Tap the nearest running water — say, an irrigation canal or a river — to generate electricity.
That electricity, he figures, could be used on-site to operate irrigation pumps or tools. Excess electricity could be sold onto the commercial grid.
Hamner, co-founder and president of Hydrovolts, based in Seattle, invented “Flipwing” technology, which he says makes turbines much more efficient than earlier designs. Under the design, hinged blades or paddles are pushed by the current, rotating a drive shaft. As the blades begin their reverse upstream stroke, they flip, presenting only their edge to the current. This eliminates almost all resistance, he said.
This also reduces to virtually zero any effect on fish in the waterway.
“It’s a drag turbine, rotating slower than the water speed,” he said. “To fish, it looks like a big wall. They either go over the top along with the paddles, or on the bottom side they swim right through.”
Hydrovolts expects to have its turbines on the market late this year, Hamner said. The largest would fit in a 20- or 40-foot-long standard shipping container. A smaller model could be carried on a boat trailer or a flat-bed truck. The smaller one, at about 900 pounds, could be handled by two people with a small crane.
There is rarely any need for site preparation, he said.
The turbine could be installed and left in the waterway during the irrigation season, then be removed for stowing or maintenance.
Maintenance would be replacement of the bearings.
“It’s completely modular,” Hamner said. “We can ship out the part; you can install it. The generator is a permanent magnet, so it won’t need replacing.”
The only other maintenance, he said, would be keeping the blades from being fouled by debris.
Prices would range from $20,000 to $30,000, which would mean a four-to-six-year payback, depending on the stream flow and the price of commercial electricity, he estimated.
“The payback would be faster in California, because you can sell the electricity for a lot at peak pricing,” he said. “Also, many states have incentives available for renewable-power generation.”
The only need for a permit would come if the turbine were to be connected to an interstate grid.
“If you’re generating less than 5 megawatts, you’re exempt,” he said.
The turbine operates on water speed rather than water pressure and generates between 1 and 20 kilowatts, depending on the speed of the current.
In testing prototypes, Hydrovolts has found the water speed needs to be at least 3 to 4 mph, which translates into 4 to 6 feet per second.
With a 6 mph current, he said, a turbine that is 40 percent efficient can make about 5 kilowatts of power. That is enough power for two modern American homes, from a device the size of an office desk, he said.
Hamner said his company is looking for sites to prove the turbine’s reliability.
“The USDA has grant programs for renewable-energy demonstration projects,” he said. “We’re thinking local communities or nonprofit co-ops.”
On his Web site, Hamner has listed the formula for calculating the energy potential for any particular site.
“We’re looking for partners to make grant applications to agencies,” he said. “I’m excited to be working with people on this.”
With a degree in marine affairs, Hamner has worked with the U.S. Army Corps of Engineers, the Washington Department of Ecology, the City of Seattle, the U.S. Agency for International Development, the Asian Development Bank and the United Nations.
In 2009, Hydrovolts won the National Sustainability Award in the Cleantech Open, dubbed the “Academy Awards of Clean Technology.”