Harness Hydroelectric Power for Off-Grid Energy

Generate off-grid electricity from a private stream with a hydroelectric turbine.
By Christopher James Marshall

Electricity generated from running water can be one of the most affordable off-grid power sources, but the use of hydroelectric turbines may be restricted in some areas.

On-Site Hydro-Electric and Cold-Sinks
There are two ways to get electrical power from streams and rivers: a turbine in the natural channel of water, or a dammed water flow that feeds into a turbine. Turbines are often prohibited in the natural channel of a waterway because it is by law public property and a turbine would be an obstacle to other users and aquatic life. A stream on your property can be dammed only if you have sufficient elevation difference (or ‘head’) between where the stream enters and leaves your property; however, there may be local restrictions on damming even on your own property due to water rights of farmers and ranchers downstream of your property.

After you determine if you have access to extract water power, then the measurements you need to take are the flow in gallons per minute (flow = volume x velocity), or in the case of a dam, measure the head, multiplied by the cross-section area of the outlet, multiplied by the force of gravity. The flow can vary seasonally as well as from the center of the channel with the maximum flow to the bank at minimum flow. The beauty of water power is that it generates 24/7, unlike intermittent solar or wind power.

Hydroelectric is electricity generated by the mechanical power of the water. Other than a dam, there are only two main components: the turbine and the generator. Overall, hydroelectric is one of the least expensive off-grid methods to produce electric power.

Vendors of water turbines are few, partly because opportunities for home water power are limited and partly because people build their own from re-purposed components. Vendors can provide tables for their turbine on how much power can be generated given your situation. The minimum size hydroelectric system would require a water source with a head of about 5 feet and a flow of about 15 gallons per second and would produce about 500 watts.