Jesse Remillard, ERS, for Zondits
A startup company, Quidnet Energy, founded by Aaron Mandell and Howard Schmidt, has the potential to drastically lower the cost of energy storage. The pilot project implemented in 2015 uses excess electricity to pump large volumes of water into an abandoned natural gas well in Texas at high pressures. When electricity generation is needed, the pressurized water is released through a turbine generator.
The concept is very similar to compressed air energy storage (CAES), which has been successfully demonstrated at grid scales for many years. CAES has not been widely commercialized, though, because when air is compressed, it generates large amounts of heat, which must be stored and transferred back to the air when it is released in order to achieve competitive efficiencies. Because water is not a gas and does not change in volume significantly when it is compressed, it does not present the same challenges of heat management that compressed air-based energy storage technologies do.
Quidnet believes it can install energy storage for $50 per kWh of energy, which would include the well, turbine generator, and permitting. Exploratory drilling is not included in this estimate, but Quidnet believes it will be able to utilize thousands of wells left over from the oil and gas industry to minimize these costs. Compared to average industry battery costs of approximately $350 per kWh, Quidnet is positioned to be a leader in energy storage if their technology is effective.
Quidnet plans to implement their next pilot project at an abandoned geothermal well in northern Nevada. The well is 14 inches in diameter, which is larger than a typical oil and gas well, making it possible to inject a higher volume of water for higher charging and discharging rates. It is believed that the new reservoir will take 14 hours to fully charge and will be capable of producing 10 hours of electricity, although it is not clear what the power output capacity will be. The new project will conveniently store energy from a nearby geothermal power plant owned by AltaRock Energy, whose CEO is also Aaron Mandell.