Cache Energy Heat Storage Pilot Project Launches in Anchorage

The chemistry of lime has been around since prehistoric times, yet the material couldn’t be used for energy storage until the process was cyclable, according to Cache Energy CEO Arpit Dwivedi. Normally, lime can be reacted once; Cache Energy patented a proprietary binding agent that can survive high temperatures.

Illinois-based Cache Energy began exploring market fit in Alaska by participating in Launch Alaska’s eight-month Tech Deployment Track accelerator program. After completing the program, Cache Energy joined the Launch Alaska portfolio in spring 2024.

“Cache Energy’s innovative new energy storage solution can play a key role in alleviating Southcentral Alaska’s impending energy crisis,” says Isaac Vanderburg, Launch Alaska CEO. “We need technologies like this to accelerate renewable energy integration, bring stability and sustainability, and protect consumers’ bottom line.”

The limestone-based technology does not rely on exotic minerals, and the system can be stored and operated under ambient conditions, even in extremely cold weather. Dwivedi says a winter’s stockpile for a town like Kotzebue, with almost 1,000 households, would fit inside a single shipping container. The water for the discharge phase is about a 55-gallon drum’s worth.

“Alaska needs unique storage technology due to seasonal variations in solar/wind availability. Cache’s technology allows Alaskans to tap into clean, affordable energy consistently throughout the year,” Dwivedi says.

For now, the pilot project at the Halliburton yard is powered by an onsite generator, for testing purposes. Dwivedi says the heat exchangers could draw electricity from any source, and the discharged hot air could be used directly for district heating or any type of waste heat generator.

Because of the chemical reaction, Cache Energy boasts of a higher capacity per unit mass than other heat storage methods, such as raising the temperature of a large mass of molten salt or ceramic. The company figures its pellets hold 500 watt-hours per kilogram, compared to the best-performing sand battery at 140 Wh/kg.

The pilot project involves a unit that could store energy for approximately fifty households, Dwivedi estimates. As the system scales up, the silo diameter grows. Stored quicklime could also be transported wherever the material is needed most.

Cache Energy has demonstrated the system over a year-long cycle. The pilot project is meant to test the reliability of the equipment under Alaska conditions. Dwivedi adds that it’s also testing the ease of use; the company deliberately hired arts majors, not engineers, to prove that the system could be deployed in communities without highly skilled operators.

Cache Energy is now working to install additional units with other Alaska partners.

Dwivedi says, “Partnering with Launch Alaska has been helpful in bringing this long duration energy storage solution to Alaska, and we look forward to demonstrating the ways in which it can benefit communities and businesses facing a variety of energy challenges.”

The long-duration energy storage startup has already won two awards from the US Department of Energy.