The photo is sourced from rplushydro.com
The PSPP will be built 56 kilometres northeast of the town of Rawlins, the county seat of Carbon County in Wyoming, one of the so-called Mountain States in the west of the country. The lower reservoir for the project will be the existing Seminoe Reservoir of the dam of the same name, with an upper reservoir to be established within 3 kilometres to the east in the Bennett Mountains. The difference in elevation between the reservoirs, which will be connected by underground tunnels, will be a little over 300 metres.
The PSPP will be connected by a 48-kilometre transmission line to the Aeolus substation located near the town of Medicine Bow in Carbon County. The excess of electricity produced by the neighbouring wind generators will be fed via the substation to the PSPP to start up the pump systems, which will pump water from the lower reservoir to the upper one during hours of low energy demand. When demand goes up, the PSPP will pump water from the upper reservoir to the lower one, supplying electricity to the households across Carbon County via the transmission line and the substation.
The $2.5 bln project will make it possible to smooth the peaks in power consumption in a state increasingly dependent on renewable energy sources (RES). While coal accounted for 97% of Wyoming’s power output in 2003, this indicator was at just 72% in the first eleven months of 2022, according to the U.S. Energy Information Administration (EIA) of the U.S. Department of Energy. The share of gas in the energy mix from January through November 2022 stood at 4%, with renewable energy sources (RES) totaling 22%, including wind generators accounting for 20%. The rates, at which wind power plants are being commissioned are rising: in 2020–2021, their installed capacity had almost doubled, exceeding 3 gigawatts (GW).
According to rPlus Hydro, there are a total of 43 PSPPs operating in the United States. Their key advantage is the possibility of multi-hour energy storage for a period exceeding a quarter of a 24-hour cycle. While the service life of a lithium-ion battery lasts 10–15 years, the lifespan of a PSPP can exceed 75 years, and PSPP efficiency is hardly affected by the number of charge/discharge cycles. However, PSPP construction requires special conditions, such as an elevation difference and natural water sources for filling reservoirs.