The system, which can store excess energy on the grid, could cut construction costs by one-third and be built in half the time of conventional plants.
Developed by the Southwest Research Institute (SwRI) in the US, the dam has been designed as an energy storage facility that can help to balance loads on the grid.
The method, known as closed-loop pumped storage hydropower (PSH), uses off-peak, surplus power to pump water from a lower-elevation reservoir to a higher-elevation one. During periods of high demand, the stored water is returned to the lower reservoir, driving turbines to produce electricity.
Although the losses from the pumping process mean it consumes more energy than it generates, it can provide energy during times of peak demand and can be used to store intermittent renewables such as solar and wind power.
“PSH accounts for approximately 95 per cent of all energy storage in the US, and modern PSH plants have a round-trip efficiency approaching 80 per cent,” said SwRI hydrologist Dr Gordon Wittmeyer.
“However, only one moderate-sized 40MW PSH plant has been constructed in the past two decades in the US. Three factors stand in the way of rapidly deploying PSH: cost to construct, time to construct and potential environmental impacts. The SwRI-developed m-Presa system addresses all three of these issues.”
To date, developers have been discouraged from investing in PSH projects due to high costs amounting to as much as $5,000 per kW of installed capacity.
The modular design could reduce construction costs to $1,500 per kW-installed capacity, the researchers said, which makes it competitive with other long-term energy storage options.
Currently, it can take up to 10 years to design, construct and commission a conventional PSH plant, but the modular design could cut this construction time significantly.
“We propose closed-loop PSH units by storing water in upper and lower reservoirs, impounded by buttress dams constructed from prefabricated structural steel modules,” Wittmeyer said.
“These structural steel modules can be transported on standard-sized flatbed trailers to allow rapid modular construction of 10 to 40ft-high buttress dams that can enclose a wide range of surface areas and water volumes.”
The researchers said that the potential environmental impact of reservoir construction could be avoided by creating artificial reservoirs that are separate from natural streams or rivers.
