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8.3 | Small-Scale Hydropower |
CHARACTERISTICS
Small-scale hydro-electric systems (under 20 MW) capture the energy in flowing water and convert it to electricity.3 Systems can be either "run-of-the-river" or "pumped storage"4 and are suitable for stand-alone (isolated) or grid-connected applications.
If they are well-designed, small hydro-electric systems blend with their surroundings and have minimal negative environmental impacts. As with larger hydro-electric systems, small hydro produces no GHG emissions.
The potential for small hydro-electric systems depends on the availability of suitable water flow. Where the resource exists, the development can provide cheap, clean, reliable electricity. Locations are numerous around the world, and are often accessible to load centers and to the grid.
SIZE:
1-20 MW
FEATURES:
Operating Efficiency: 85-88%. Capacity factors vary from 20-90% depending on the variability in streamflow.
To produce 200 watts, water sources must have, at a minimum, a change in elevation (or head) of 20 feet @ 100 gallons/minute (or 100 feet of head @ 20 gallons/minute). Areas with a low head will need long runs of large-diameter pipe. Also, distances of over a few hundred feet may require construction of expensive cabling
COST:
$1,000-3,000/kW. Costs vary widely based on site-specific factors such as streamflow, geological characteristics, and extent of existing civil structures at the site. Major costs are associated with site preparation and equipment purchase.
CURRENT USAGE:
As of 1993, 20% of global electricity was generated by hydro; small-scale hydro plants of 10 MW or less account for 4% of total hydro generation.
POTENTIAL USAGE:
The continents of Africa, Asia and South America have the potential for 1.4 million MW–four times as much capacity as is currently built in North America. Less than 10% of the world's (total–large and small) technical usable hydropower potential is being used today.
ISSUES ASSOCIATED WITH IMPLEMENTING ACTION
- Availability of resources is site specific and may not be located close to demand centers.
CLIMATE CHANGE IMPACT
EMISSION EFFECT:
CONDITIONS FOR EMISSIONS MITIGATION:
- Hydropower produces no GHG emissions. Environmental impact may occur due to land-use or siting issues.
EMISSION ESTIMATE:
Produces no greenhouse gas emissions.
COST-EFFECTIVENESS:
$25-38/ton of net CO2 avoided
SECONDARY EFFECTS:
Produces no air pollutants.
RESOURCES
CONTACTS
U.S. Hydropower Council for International Development
Debby Stone
Director, Trade Promotion
Washington, DC
Tel: (202) 383-2550
Fax: (202) 383-2555
National Hydropower Association
Washington, DC
Tel: (202) 682-1700
Fax: (202) 682-9478
hydroinfo@hydro.org
http://www.hydro.org
U.S. Department of Energy
John Flynn
Hydropower Programs
Washington, DC
Tel: (202) 586-8171
Fax: (202) 586-8185
john.flynn@ee.doe.gov
http://www.inel.gov/national/hydropower
3Even smaller, or microhydro (2-300 watt) systems are appropriate for residential applications.
4
Run-of-the-river hydroelectric plants use the power in river water as it passes through the plant without causing an appreciable change in the river flow. Normally such systems are built on small dams that impound little water, or may be built without any reservoir or dam.
Pumped storage projects provide a means of storing energy. Excess off-peak energy is used to pump water to an upper reservoir where it is stored as potential energy. The water is then released to produce peak-load power when necessary.
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