Think of it as the love child between a steamboat paddlewheel and a small hydroelectric dam.
Seattle, Wash.-based Hydrovolts has devised an "in-stream hydrokinetic turbine" for harvesting electric power from canals, irrigation networks, wastewater systems and the streams in and around industrial sites.
The four-bladed turbines are placed in relatively slow moving water courses and, when they turn, power is generated, similar to the way hydroelectric dams generate power. A six-foot by four-foot turbine in an irrigation canal flowing at two meters a second might produce 1.5 kilowatts, said COO Chris Leterle. The same turbine in a four-meter-per-second stream might produce 6 kilowatts to 8 kilowatts.
That pales in comparison to some of the tidal turbines and wave machines currently being tested in Scotland and Australia, but that's the idea. Other marine energy companies are faced with the daunting challenge of building systems that can survive some of the harshest environments on the planet with very little maintenance. To become economically viable, these systems also have to connect to the grid from miles out at sea. Some of these systems, like the 250-kilowatt tidal turbine created by Open Hydro (see video here), rival the size of small ships. WaveBob, an Irish company, aims at megawatt-size devices.
By contrast, Hydrovolts wants to make turbines that will produce local power for pumping stations, that will never experience a drop of salt water, and that will face tides that most people could navigate while drinking beer and floating in an inner tube. Thus, the headaches that go with expensive grid infrastructure, corrosion and extreme weather wither. And, at 300 pounds, they can be easily repaired.
"In the emerging world, our device can be plucked out by two guys," he said. "This is more of a product than a project."
Stream turbines actually enjoy a lengthy history. The Eling Tide Mill in Britain dates back 900 years. Startup Rentricity, meanwhile, is producing micro-hydro turbines that harvest power from the pressurized streams inside of municipal water agencies.
Hydrovolts secret sauce is that its turbine resists fouling, so repairs-ideally-will be minimal. It also has a hinge on the paddles to increase performance and reduce resistance. When a given paddle is in the 12 o'clock position, the current is pushing it with maximum force. When the same paddle is sinks to the 6 o'clock position, however, it would ordinarily become an impediment. Hydrovolts has figured out a way to let the paddles swing free in the down position to prevent that. See YouTube clip here.
Finding suitable streams is not as difficult as it sounds. "Nationwide, there are 500 irrigation districts. There are 37 in Washington state alone," he noted. A typical irrigation district might control 75 to 100 miles of main canal and 50 to 75 miles of tributaries. A typical main irrigation channel might be able to support five to six turbines.
The company has recently been fielding inquiries from several potential customers overseas, including a gold mine in Panama.
Hydrovolts would like to start selling commercial devices by the first quarter of 2011, but it has hurdles to clear. It has made and tested a few prototypes and is currently raising money.
Image courtesy Hydrovolts