The following is an excerpt from a case study from the Energy Alternatives
Microhydro Online Course.
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CASE STUDY: A Simple Battery Charging System
A family of five living in an off-grid house wanted lights,
music and modern conveniences, about a level 3 on the Capacity and
Consumption self-rating scales. One challenge of their location
was winter freezing, where plumbing is routinely buried up to 6
feet deep. They were hoping to avoid the bother, expense and
permanence of such a “civil engineering” project.
An advantage to their site was lots of water, the creek flowed at
hundreds of US gpm, even at low water.
||4-inch Turgo “Stream Engine” from Energy
Systems and Designs
|Pipe length and material
||600 feet of 2-inch poly
|Water volume available
||lots – hundreds of gpm
||100 US gpm
||150 kWhrs/month (208 continuous watts)
The major construction consideration for microhydro in cold climates
is the protection of the pipe from freezing temperature. Burying
below the frost line is the usual method, giving excellent mechanical
protection as well. However, in rugged terrain, this can be a formidable
Two-inch poly is terribly rugged. Here, the owner laid the
pipe right in the creek bed to protect from freezing.
This is not usually recommended, as holes can become abraded into
the pipe over time as it rubs against the rocks. However,
this system has run for a few of winters without problem, so there
A pressure gauge shows that there is about 15 psi, when the water
is flowing. Since the owner told us that a one-inch jet is used,
the water flow is about 100 US gpm through the Stream Engine. The
system delivers over 200 continuous watts to the batteries, a few
hundred feet up the steep slope.
This illustrates that electrical generation can be both pretty
casual and quite powerful. Actually, this system has a jet that
is too big for the length of the pipe used. More water is being
used than is strictly necessary, meaning that the pressure is lower
than it could be. However, since there is lots of water in the creek,
and lots of power in the batteries for the loads that are being
used, it just wasn'’t worth resizing the jet, says the owner.