Comment from Just Have A Think #142 – 2021-03-07
I have to remind Dave that these microhydro systems do have downsides. The 24/7 requirement is getting more difficult because large hydro projects upstream can make the river highly variable, and rivers often slow to a trickle or dry up after the spring rains / snow melts. So variability of the water supply is a major problem, and that’s why most hydroelectric systems include the dam.
But there is another microhydro system that has other advantages: the water source is a spring up on the side of a hill. I’ve seen a system where the spring puts out maybe 16 or so liters per minute, and the head or drop from the spring to the turbine is around 50 meters. With a Pelton type turbine and a pair of nozzles of maybe 6 mm, the turbine can generate a half a kilowatt or more.
The best thing about this spring fed system is the water flow is very stable year round. There is almost no danger of flooding and the water may be pure enough for use in the home. With a storage tank up on the hill, the higher, short term demands can be met with a controller that senses the demand and controls the water to the turbine. This could be used for cooking or heating water. Or a battery system can be added for reliability. The idea is to get away from using streams or creeks which are subject to the ups and downs of weather. In colder climates there may still be the problem of the water turning to ice, so a battery system may solve that problem.
BTW the hydro system without a dam is called run of the river.