A New Era in Small-Scale Hydropower

With a small-scale hydropower system, even a relatively small stream can offer a lifetime's escape from electric utility bills.

| April/May 1994

  • 143 small scale hydropower - turbine blades
    The interior of a small turbine.
  • 143 small scale hydropower - stream
    With a high enough head, a small scale hydropwer system can generate electricity from a little stream like this.
  • 143 home owner hydro - table, feet of head
    The chart gives you a good idea of how much output in watts you may expect per different gpm (gallons per minute), for varing feet of head. Multiply the number of watts by 24-watt-hours to get the total number of watt-hours generated in one day. Divide this by system voltage to get your amp-hour per day output.
  • 143 small scale hydropower - turbine, inset
    The turbine unit with attached feeder pipes.
  • 143 small scale hydropower - turbine, batteries, inverter
    The powerhouse that services the Coulter ranch houses the turbine, (left) batteries (center, in wooden box),  and the power-center and DC to AC inverter (right)
  • 143 home owner hydro - diagram, typical setup
    A typical hydroelectric layout. 1. Site of dam or weir to divert water. 2. Stock tank or pond 3. Penstock. 4. Powerhouse with electric lines running to home. 5. Rock-lined tailrace.

  • 143 small scale hydropower - turbine blades
  • 143 small scale hydropower - stream
  • 143 home owner hydro - table, feet of head
  • 143 small scale hydropower - turbine, inset
  • 143 small scale hydropower - turbine, batteries, inverter
  • 143 home owner hydro - diagram, typical setup

Two years ago, Norm and Sue Benzinger, owners of the Coulter Lake Guest Ranch, a wilderness retreat in th Rockies, had a problem: They were seeing too much of the propane delivery man.

The ranch's propane bill had topped $10,000 in 1992—much of it consumed by a generator. Hoping to slash his energy costs, Norm contacted Ken Olson, a renewable energy expert who directs Solar Energy International in nearby Carbondale, Colorado.

"He said he had a stream falling down the hillside," recalls Olson. "Turned out it was a great water power site."

Working together, Olson and Benzinger installed a hydroelectric turbine. Now the generator, which used to drone for hours a day, has fallen silent. A water power system that cost $6,000 will save $2,500 in its first winter.

Over the last 10 years, small-scale hydropower technology has taken a quantum leap thanks to the invention of the microturbine. Inside a metal case that is smaller than a bread box, a miniature water wheel, not much bigger than a cinnamon roll, is coupled to a pickup truck generator. When the wheel is spun by a jet of pressurized water, electricity is created. The design is simple yet sophisticated, a triumph of appropriate technology.

Progress has also been fueled by the dramatic evolution of solid-state inverters and load controllers—the brains in the Benzingers' system. A decade ago, inverters, which transform direct current (DC) to alternating current (AC), and con trollers, which govern electrical production, were dumb, unreliable, and inefficient beasts. Tamed with computer chips, they now perform the same tasks in a much more intelligent, reliable, and energy-efficient manner.

Bob Marrs
10/9/2008 12:04:34 PM

Vincent, What you are proposing is a perpetual motion machine, something that produces more energy than it uses. Or let me put it this way, in a perfect world with no mechanical or electrical losses, the amount of electricty that could be produced by 1 gallon of water falling 10 feet (say) is just enough to repump that 1 gallon back up 10 ft. In the real world, the 1 gallon falling 10 feet would produce enough electricity to pump the 1 gallon back up about 7 feet. Cheers Bob

1/12/2008 4:25:28 AM

Hi i know this is an old article but ill see what happens. I'm just wondering whether a closed circuit with an electric pump that produces flowing water around a pipe system with a number of generators in it then back to the pump to start all over again would produce enough electricity so that both the pump could be powered by it and also there be an excess of electricity that could be stored in a battery for home use? Not being a physics student I have no idea how to crunch the numbers. If you can be of any help that would be much obliged, if not thanks anyway.

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