Hydropower Vision: Hydropower and The Grid

It’s widely known that hydropower is clean and renewable. But it’s 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

Source Material: U.S. Department of Energy, Hydropower Vision: A New Chapter for America’s 1st Renewable Electricity Source