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Hydropower is one of the oldest and largest sources for generating clean, renewable, and affordable electricity.
Discover the science behind hydropower and why it will continue to power your today and tomorrow.
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The science behind hydropower and why it will continue to power your today and tomorrow.For more than a hundred years, we have been capturing energy from moving water. Hydropower, or hydroelectric power, is one of the oldest and largest sources for generating clean, renewable, and affordable electricity. According to the Energy Information Administration, today, it generates a little more than 6% of the nation’s electricity and plays a significant role in maintaining the reliability and resiliency of our power grid.
The Neal Shoals Facility in Carlisle, South Carolina is the oldest hydropower station in our resource portfolio and began operating in 1905. Our other 8 conventional hydropower facilities are spread across 4 states and generate enough energy to power about 284,000 homes.
Traditional hydroelectric plants use a dam on a river to store water in a reservoir. When water is released from the reservoir, the rush of water sets turbines in motion, which activates a generator that converts force into electricity.
For example, at our Roanoke Rapids Hydro Power Station, when water flows from the lake through the powerhouse, the station's four generators can produce up to 95 megawatts. In one hour, the station can produce as much electric energy as 8 typical homes use in one year.
Pumped storage plants such as our Bath County Pumped Storage Station store energy – think of it as a giant battery. Unlike a traditional hydropower facility, pumped storage stations have two reservoirs, allowing them to “recharge.”
When energy demand is low (such as when we are not using home appliances in the late evening), these facilities will pump water uphill from the lower to upper reservoir, against the force of gravity — thereby “charging” the battery. When demand is high, water in the upper reservoir is allowed to flow to the lower reservoir, passing through a turbine to generate electricity as it travels.
Energy storage is important in ensuring a consistent flow of electricity due to the natural fluctuations in wind and solar power throughout the day. Pumped storage hydropower (PSH) has a greater storage capacity and longer duration than battery storage technologies currently being deployed at commercial scale. In 2018, the International Energy Association estimated that the volume of PSH plants is estimated at 9,000 gigawatt hours (GWh), whereas batteries amount to just 7 GWh.
Our Bath County Pumped Storage Station represents close to 13% of the pump storage capacity in the United States. The station’s total output capability is over 3000 megawatts – which is enough energy to power over 750,000 homes.
Hydropower stations are an important part of our resource portfolio because of their ability to generate power for the grid immediately. This attribute makes hydropower an ideal complement to renewables like wind and solar, which are more variable in their electricity output. Hydropower can meet demand when these intermittent sources are unavailable – when the wind is not blowing and the sun is not shining, which has a stabilizing effect on the power grid.
Hydro plants play a crucial role in providing essential backup electricity. Their generators can quickly be started or stopped, making them more responsive than many other energy sources in meeting peak demand. As a result, hydro plants are particularly valuable in restoring power during widespread outages or system disruptions.
How we generate energy is constantly changing – but hydropower is here to stay. Hydropower will continue to play a critical role in serving as backup power to various renewables and maintaining a reliable grid for years to come.
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