With the energy transition away from fossil fuels and coal a top priority among many policymakers and voters, hydropower stands to play a much larger role in how we power this world in the coming years. Not only is it clean – CO2 is emission free – and renewable, but it can be used for water/waste management, water distribution and irrigation control. Perhaps the stronger argument for hydropower is that it provides ancillary services to the grid, which are vital to maintaining continuous power during a significant weather event. The 2021 “snow-pocalypse,” as it’s been dubbed by Texas residents, and the ensuing power outages, are proof that our grid needs all the help it can get.
Other renewables such as wind and solar are variable, and hydropower, particularly pumped storage hydropower (PSH), can pick up the slack when they are not producing power. PSH involves a dam with two reservoirs, an upper and a lower one, and a turbine. It can store energy by pumping water into the upper reservoir; when the energy is needed, the water will be released into the lower reservoir turning the reversible Frances turbines to create energy. The PSH cycle maintains an approximately 80 percent efficiency rate.
Additionally, PSH is the most massive battery technology out there and it provides system and balancing services to the grid. It is large-scale, cost efficient and the lowest cost for energy storage in existence. A dam has a lifespan of 100 years and hydro storage plants have more than 40, so the large cost that is required for initial investment is offset by the production lifespan. It is an incredibly efficient use of energy and resources as, by the end of its lifespan, it will have provided more than 150 times the amount of energy used to construct it – beating out all other solutions by far. Also, closed loop hydro plants do not need to be near a river and can be put wherever grid support is required.
A metaphor by Direct Energy Business that explains why it is so crucial to add reactive power to the grid suggests thinking of the energy transmission system like the municipal water system and voltage like water pressure. Water will not run through the pipe without pressure, but too much pressure will cause the pipes to explode. PSH can provide reactive power to the grid to keep voltage levels steady by absorbing power when it isn’t needed and generating it when it is. PSH can regulate frequency of voltage using synchronous inertia, or kinetic energy, by increasing and decreasing the speed of the rotating mass to balance supply and demand. PSH can employ virtual inertia by using the energy stored within it when there is a decrease of frequency in the network.
Grid stabilization is made possible so that low-inertia, variable renewables, such as wind and solar, can benefit from the high inertia of the revolving mass. The increasing number of intermittent sources decreases the grid’s inertia, leading to instability. PSH allows these variable renewables to enter the grid without causing problems and be transmitted large distances. Future technology is leading to a grid with far less rotating mass and will be relying more on hydropower for its power storage and inertial grid stability benefits. Ninety-three percent of the U.S. storage capacity, or 22.9 GW, is accounted for by water storage, which means that PSH takes the storage capacity of any other battery and multiplies it by 100 – blowing the competition out of the water, so to speak.
The western United States is home to some of the largest hydropower dams. Washington, California and Oregon are the sites with the highest concentration of hydroelectric generation capacity. The U.S. hydropower plant with the greatest generating capacity is the Grand Coulee Dam in Washington. Of all states East of the Mississippi river, New York can boast of having the most conventional hydroelectric generating capacity, the next being Alabama. A whopping 79,946 megawatts (80 million kilowatts) total generation capacity in the U.S. in 2020, and the breakdown is as follows: 27% from Washington, 13% from California, 10% from Oregon, 6% from New York, and 4% from Alabama.
In the U.S., we have plans for the Red Rock hydropower plant on the Des Moines River in Iowa, which will have a 36.4 megawatt generation capacity. Although there is quite a bit of generation capacity in the works, experts say that we will still need to double the amount of hydropower capacity worldwide to reach net-zero emissions by 2050 and, at this point, we are far from the mark!
Headline photo: The Grand Coulee Dam in Washington state.
Shannon West graduated with a Bachelor of Liberal Arts in Psychology from Texas State University, where she developed a knack for writing research papers and case study analyses. After years of helping friends edit their university papers and cover letters, she is now putting those skills to use by copy editing and writing here at OILWOMAN Magazine.