Stored electrical energy will eventually be a regular part of every electrical contractor's conversation. The subject is driven by the push to find sustainable sources of electrical energy—from the sun, wind and other sources—and capture that energy for later use.

Available energy, when you need it

Batteries are the traditional way to store energy. There’s an all-out race to make batteries better, charge faster and hold a charge longer, and have the electrical charge available when you need it. All these characteristics are affected by conditions such as temperature, altitude, capacity, cycles and more.

But what if environmental conditions could be tweaked so electrical energy could be saved by freezing it, and then using it later when it is unfrozen?

That’s precisely what scientists at the Department of Energy’s Pacific Northwest National Laboratory propose in a study published in April 2022. They have introduced the concept of a “freeze-thaw battery.” It’s a battery that literally freezes its energy for later use. It’s significant because it enables consumers of electricity to have energy available later than the energy is created.

Molten salt

The batteries use a dielectric of molten salt from an aluminum-nickel (Al-Ni) compound that is ideal for the freeze-thaw process. The research states their concept aptly that “grid-level storage of seasonal excess can be an important asset to renewable electricity. By applying the freeze-thaw thermal cycling strategy, here, we report Al-Ni molten salt batteries with effective capacity recovery over 90% after a period of 1–8 weeks as a proof-of-concept.”

If the use-case of such energy storage works, it serves to greatly change how sustainable energy is made available for the grid, with a supply that's available for the sometimes-difficult demand fluctuations posed.

Seasonal storage?

This makes it ideal for seasonal storage, where energy may be saved in one season, and consuming that energy in another season when the environmental conditions may not be producing as much electrical energy. For example, excess energy produced by solar panels in the summer when there is plenty of strong sunshine could be stored for later use in the fall when there is less sun.

We’re always seeking energy that’s sustainable. The sun’s rays offer energy again and again. The flow of rivers and waterways provide energy from hydroelectric power generation. Wind power is generated by wind turbines. The supply of these and other sources may be infinite, but their availability is restricted by nature.

As the DOE scientists note in their research, the Pacific Northwest in the spring is ideal for power generation, as rivers heavy with runoff power hydroelectric dams to capacity by strong winds from the nearby Columbia Gorge. But such power must be harnessed and captured. Until now, its duration was limited. With freeze-thaw batteries it may be captured, frozen and thawed for use later.