Energy: MATERIALS ENCYCLOPEDIA
Turbine (many styles to suit different conditions)
Penstock (water intake)
Tailrace (water release)
Valves and controls as required
How the system works
A turbine converts the flow and pressure of falling water to mechanical energy, which turns a generator to produce electrical current.
A waterway must have a suitable amount of head (elevation between inlet and outlet points) and flow (quantity of water) to make a useful amount of power.
A penstock diverts some water from the high point in the system and directs it to the turbine. The pressurized water is passed through the turbine, causing it to spin and turn the generator to produce current. The water leaves the turbine and rejoins the flow of the river or creek.
There are numerous styles of turbine, each one suited to particular head and flow characteristics.
Valves are installed to shut off flow for servicing.
Output figures are based on available head and flow and the efficiencies of the piping and turbine. Very low head, low flow systems can generate as little as 20 watts, while the upper limit of micro-hydro is generally accepted to be 100 kilowatts. Larger output systems are considered to be full-scale hydro electric projects.
A water turbine system produces power constantly, unlike solar and wind systems. Even relatively low output can add up to a significant amount of power.
Environmental impacts: low
Micro hydro emits no carbon or other pollutants to produce power. The units will produce many times more power than was used in their creation.
Proper design should ensure that a small scale Run of River (ROR) system does not have a detrimental impact on the ecology of the waterway. Intake pipe(s) do not require damming or altering of the watercourse, and the tailrace can be designed to prevent erosion.
Material costs: low to Moderate
Labor input: high
The amount of modification required to the water source, in addition to the amount of piping and controls, will determine the labor input for a micro-hydro installation.
Skill level required for the homeowner
Installation — Moderate to Difficult. Even small amounts of flowing water can produce forces that are difficult to manage. Cold climates will require special considerations to avoid having the system freeze.
Use — Easy.
Maintenance — Moderate to Difficult. Monthly inspections of turbine, intake, tailrace and valves.
Sourcing/availability: moderate to difficult
There are a limited number of system designers and manufacturers, and it can require diligent research to find the right people and equipment for a successful installation.
Electrical codes will cover the wiring of a system. Building codes will not apply to micro hydro systems unless a powerhouse of sufficient size as to be covered by codes must be built. Conservation authorities and environment and fisheries ministries may need to issue permits to allow the use of a river or stream for micro hydro.
A properly maintained micro hydro system will be very durable. The turbine bearings will need scheduled replacement, but the balance of the system should last for decades.
Waterways are subject to intense flooding, which can cause damage to systems.
Water turbine technology is well developed, and unlikely to change dramatically. Utility companies are showing renewed interest in the many hydro installations that exist along rivers in many parts of the continent, and that used to power mills and small industries. This infrastructure of dams and penstocks represents a large amount of potential green energy that is likely to be redeveloped.
Water turbines can be created in a low- or no-energy scenario, and are a valuable resource for resilient living.
Tips for successful micro hydro power
1. Accurate measurements of head and flow are critical for system design.
2. Permits from a variety of government agencies may be required.
3. Consider annual high and low water levels and ice depth when assessing a site.
4. Size power cables properly to account for the distance between generator and point of power use.
5. Place the turbine where it can be easily accessed for servicing in high and low water conditions.
6. Provide adequate screening at the intake to prevent debris from clogging or damaging the turbine.
7. Install control valves at the top and bottom of the penstock to isolate the turbine for servicing.