A human-portable hydroelectric generator that weighs about 30 pounds and generates 500 watts of power may soon be a new option for off-grid power.

Developed by Bourne Energy of Mailbu, California, the Backpack Power Plant can create clean, quiet power from any stream deeper than 4 feet.

The company showed off its more-rugged, militarized version of the Backpack Power Plant at the Cleantech Forum in San Francisco last week. Bourne Energy CEO Chris Catlin estimates the system will cost $3,000 after it goes into production.

"The BPP-2, which operates silently with no heat or exhaust emissions, is 40 percent less visible during operation and can also be bottom mounted to be totally invisible," the company maintains.

Off-grid solar cells are also quiet, but they don't make much power relative to the mini-turbine. For example, one commercially available foldable solar panelmeasures about 12 square feet and produces 62 watts of peak power. You'd need 60 square feet of panels to get the same peak power as the BPP-2, and the panels would only generate electricity while the sun was shining.

To install the civilian BPP, you would dig two trenches on opposite sides of a river and insert a lightweight anchor into each. Then, you'd run a synthetic rope between the anchors and the BPP. Catlin said his company designed the system to work like the high-tension mooring systems that hold up floating oil rigs.

The military version of the BPP has been designed to work with a variety of flow rates. The civilian version was designed to function best in streams moving at 2.3 meters (7.5 feet) per second.

The civilian market for a $3,000 mini hydro system might not be huge in the industrialized world, but Catlin hopes the plant will find willing customers in developing nations and the military.

"This can bring a cheap, highly portable energy technology to remote areas and remote villages," Catlin told Wired.com.

Bourne is currently looking for $4 million in venture capital to take the BPP from prototype to production.

Photo courtesy Bourne Energy

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