SMALL HYDRO SYSTEMS

The world's developing nations hold vast potential for hydropower development. Small hydropower, with its multiple advantages as a decentralized, low-cost and reliable form of energy, is in the forefront of many countries' programs to achieve energy self-efficiency. Small hydro allows for rural electrication, petroleum substitution, rural development of isolated.

PUMP STORAGE

PUMPED STORAGE projects are 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.

Pumped storage projects are net consumers of energy because power is lost in the pumping/generating cycle. It takes about 1.5 kilowatt-hours of electricity to pump the amount of water into storage that can later be used to generate 1 kilowatt-hour of electricity. The system can therefore be considered to operate at about two-thirds efficiency. Because the excess power used to pump water into storage would otherwise be wasted, however, the losses in the system are not really a concern. Pumped storage is also beneficial in emergency situations such as the breakdown of other power plants.

RUN-OF-THE-RIVER HYDRO PLANTS

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. Many times a reservoir and a dam are not even required, so a run-of-river project may not cause the water quality changes such as higher temperature, low oxygen decrease food production, increased phosphorus and nitrogen, or decomposition products associated with other hydroelectric systems.

Run-of-the-river hydroelectric plants do not normally affect downstream habitat or terrestrial habitat. Effects such as oxygen depletion, temperature elevation, inadequate minimum flows and ladder rejection by fish are not problems.