Types of Hydropower

icon box image


The most common type of hydropower plant is an impoundment facility that uses a dam to store water in a reservoir. Water from the reservoir flows through a turbine and activates a generator to produce electricity

icon box image


Run-of-river facilities channel part of a stream through a powerhouse before the water rejoins the main river. Generation depends on natural incoming flows.

icon box image


Conduit/canal hydropower projects divert water from a reservoir, lake or river through a pipe. The water flows through hydraulic turbines on its way to its ultimate destination, which may be to irrigate crops. By fitting these existing pipes with turbines, a new, efficient, innovative power source is born out of generation that’s otherwise uncaptured.

Hydropower has generated clean, affordable electricity for more than 100 years. According to EIA, in 2016 hydropower was still the largest source of renewable electricity with 103GW of installed capacity (79,948MW conventional and 22,670MW of pumped storage). Today the U.S. hydropower fleet contains 2,198 active power plants. Forty-eight states have hydropower facilities, and ten of these states generated more than 10% of their electricity from hydropower.

Hydropower’s Growth Potential

Today, clean and renewable hydropower provides energy to over 30 million American homes. As impressive as that sounds, its growth potential is immense. New analysis from the U.S. Department of Energy’s Hydropower Vision Report found that hydropower can sustainably grow its current 101 gigawatts (GW) of capacity by nearly 50 GW by 2050.

To be sure, each megawatt of power we add would have a positive impact on the communities we serve – leading to a healthier America.  For example, 50 by 2050 means nearly 5 million fewer cases of acute respiratory symptoms and 750,000 fewer cases of childhood asthma.

Learn more about unlocking hydropower’s potential here

Hydropower Enables More Renewables on the Grid

Hydropower enables greater integration of renewables (wind/solar) into the grid by utilizing excess generation, and being ready to produce power during low wind and solar generation periods. PSH also has the ability to quickly ramp electricity generation up in response to periods of peak demand.

Learn more here


Who owns hydropower facilities? Well, there are three main classifications of hydropower facility ownership: federal, public, and private. There are also ownerships through public-private and public-federal partnerships.

The three main federal agencies authorized by Congress to own and operate hydropower: U.S. Army Corps of Engineers (Corps), Reclamation, and the TVA. These agencies operate about 49% of the total installed hydropower capacity through ownership and operation of about 10% of the total number of hydropower facilities.

Public ownership includes public utility districts, irrigation districts, states, and rural cooperatives, whose hydropower resources consist of about 24% of total installed U.S. capacity and 27% of the total number of hydropower facilities.

Private owners, including investor-owned utilities, independent power producers, and industrial companies, control about 25% of total installed capacity and 63% of the total number of plants.

The Unique Value of Hydropower

It’s widely known that hydropower is clean and renewable. But its value to the grid too often goes unnoticed. Here are a few ways hydropower benefits America’s electrical grid:

  • Load-following and flexibility reserve: The ability of the power system to balance variability existing in the load over longer timeframes than regulation and frequency response, from multiple minutes to several hours. Most U.S. hydropower units are able to and do effectively provide load following to an hourly schedule, as well as following ramps that occur within the hour time scale.
  • Energy imbalance service: The transmission operator provides energy to cover any mismatch in hourly energy between the transmission customer’s energy supply and the demand that is served in the balancing authority area.
  • Spinning reserve: Online generation that is reserved to quickly respond to system events (such as the loss of a generator) by increasing or decreasing output. Except when already running at full load, hydropower offers an excellent source of reserve because it has high ramping capability throughout its range.
  • Supplemental (non-spinning) reserve: Offline generation that is capable of being connected within a specified period (usually 10 minutes) in response to an event in the system. Offline hydropower generation is capable of synchronizing quickly, and can provide non-spinning reserve to the extent that sufficient water supply is available to the unit for generation.
  • Reactive power and voltage support: The portion of electricity that establishes and sustains the electric and magnetic fields of AC equipment. Insufficient provision of reactive power can lead to voltage collapses and system instability. All hydropower facilities are operated to follow a voltage schedule to ensure sufficient voltage support. Reactive power is typically a local issue. Because hydropower facilities are often located in remote areas, their ability to provide reactive power in such locations can be essential.
  • Black start (restoration) service: The capability to start up in the absence of support from the transmission grid. This capability is of value to restart sections of the grid after a blackout and can typically be provided by hydropower.