View: An Intro to Run-Of-River
View: An Intro to Run-Of-River
This resource includes the following information:
Run-Of-River hydro projects can be any size. Generally though, small and micro-hydro projects are the primary type of Run-Of-River hydro system. Although the definitions vary, a micro-hydro system is considered by BC Hydro to be one less than 2 MW in capacity.
Small hydro refers to projects with installed capacities between 2 and 50 MW. Run off-river, micro hydro projects are similar to large-scale hydro except for the amount of power generated. Definitions vary, but generally, micro hydro systems generate less than 22.5 kW, and beyond the amount of electricity generated, micro hydro systems are primarily for a home owner’s use - although they are compatible with net-metering systems where applicable.
Diversion and intake collect the water
Penstock transports the water to the turbine
Turbine and generator convert the kinetic and potential energy in the water to electrical energy
Stand alone run of river hydro systems are used to provide power to homes, farms and small commercial businesses. If the system is capable of generating enough power to meet the peak demand, the system can generate AC just like a diesel generator. In a residence the peak demand can be managed to about 2 kW. An AC system is usually less expensive per kilowatt because there is no DC wiring or components and there are fewer components overall.
Before considering a micro hydro system, the site must have a sufficient volume of falling water, usually in the form of a creek. Within the West Kootenay region, there are many potential micro hydro sites.
From an environmental perspective, a general recommendation is that no more than 20 - 50 percent of a creek’s flow should be diverted for a micro hydro system. The vertical distance the water falls is called head and is measured in metres or units of pressure. The quantity of water is called flow and is measured in cubic metres per second (m3/s) or litres per second (l/s). More head is usually better because the system uses less water and the equipment can be smaller.
The turbine also runs at a higher speed. At very high heads, pipe pressure ratings and pipe joint integrity become problematic. Since power is the product of head times flow, more flow is required at lower head to generate the same power level. More flow than required is desirable since less water needs to be diverted from the creek. This means there will be fewer adverse environmental effects.
net head (m) x flow |
m³ |
x conversion factor = output (Watts) |
s |
Net head is the pressure available after subtracting losses from pipe friction. Most hydro systems are limited in output capacity by stream conditions. This means that the sizing procedure may be based on site conditions rather than power needs. System capacity may be dictated by specific circumstances (e.g. water dries up in the summer). If insufficient potential is available to generate the power necessary to operate the average load, you must use appliances that are more energy-efficient and/or add other forms of generation equipment to the system. Hybrid wind/solar photo-voltaic/hydro and utility systems are very successful and the energy sources complement each other. The systems described here are called "run off river"; i.e. water is not stored behind a dam. Only an impoundment of sufficient size to direct the water into the pipeline is required. Power is generated at a constant rate and if not used, it is stored in batteries or sent to a shunt load. Therefore, there is little environmental impact since minimal water is used. There is also much less regulatory complication
Q: A more recent application of wind power is to?
a. generate solar energy
b. generate electricity
Q: Wind power is used in remote locations for:
a. Water pumping
b. Residential electricity
c. Data acquisition
d. Telecommunications
Q: What is the cost of electricity from operating a generator?
a. From 25 cents/kWh for large community diesel generators to over $1/kWh for small gas generators. Fuel transportation costs are a significant factor in remote locations and can easily double these figures.
b. $1.00/kWH
