Hydropower is used primarily to generate electricity. Broad categories include:
Conventional hydroelectric, referring to hydroelectric dams.
Run-of-the-river hydroelectricity, which captures the kinetic energy in rivers or streams, without a large reservoir and sometimes without the use of dams.
Small hydro projects are 10 megawatts or less and often have no artificial reservoirs.
Micro hydro projects provide a few kilowatts to a few hundred kilowatts to isolated homes, villages, or small industries.
Conduit hydroelectricity projects utilize water which has already been diverted for use elsewhere; in a municipal water system, for example.
Pumped-storage hydroelectricity stores water pumped uphill into reservoirs during periods of low demand to be released for generation when demand is high or system generation is low.