In traditional pumped hydro storage facilities, electric pumps move water uphill, into a natural or manmade body of water. Then, when electricity is needed, that water is released and flows downhill past a turbine, generating electricity. Quidnets approach instead pumps water down into impermeable rock formations and keeps it under pressure so it flows up when released. Its like pumped hydro, upside down, says CEO Joe Zhou.
Quidnet started a six-month test of its technology in late 2024, pressurizing the system. In June, the company was able to discharge 35 megawatt-hours of energy from the well. There was virtually no self-discharge, meaning no energy loss, Zhou says.
Inexpensive forms of energy storage that can store electricity for weeks or months could help inconsistent electricity sources like wind and solar go further for the grid. And Quidnets approach, which uses commercially available equipment, could be deployed quickly and qualify for federal tax credits to help make it even cheaper.
However, theres still a big milestone ahead: turning the pressurized water back into electricity. The company is currently building a facility with the turbines and support equipment to do thatall the components are available to purchase from established companies. We dont need to invent new things based on what weve already developed today, Zhou says. We can now start just deploying at very, very substantial scales.
That process will come with energy losses. Energy storage systems are typically measured by their round-trip efficiency: how much of the electricity thats put into the system is returned at the end as electricity. Modeling suggests that Quidnets technology could reach a maximum efficiency of about 65%, Zhou says, though some design choices made to optimize for economics will likely cause the system to land at roughly 50%.
