After 12 years of research and development, a team of scientists from the Eindhoven University of Technology in the Netherlands believes that their “heat battery” can soon get millions of homes in Europe off of their gas dependency—and considering the conflict between Russia and Ukraine, this news couldn’t have come at a better time.

The team’s heat battery is based on two simple elements: salt and water. It utilizes an old thermochemical principle, which is that when water is added to salt, it produces heat. Heat can also be used to evaporate the water and store heat energy inside the salt.

Using this method of storing heat within dry salt makes the battery completely loss-free, resulting in an incredibly efficient method of energy storage. This will prove even more useful when the energy is sourced from renewables like wind and solar as they tend to fluctuate significantly and require gas or other energy sources to supplement them.

On top of that, the heat that is to be stored in the salt can be sourced from industrial by-products such as residual “heat waste” in factories or surplus heat from data centers, making it all the more sustainable and efficient.

“If industrial residual heat could be used to heat homes, you have a win-win situation: homes could be made independent of gas—an even more urgent need given the dependence on Russian gas—and CO2 emissions would be reduced,” reads a statement published by the Eindhoven University of Technology.

The first prototype was capable of providing heating for an average family of four for two days. It has since been upgraded to a fully working prototype that could be used in the real world. The system, which is about the size of a large cabinet, could heat a home for up to two months.

Later this year, a pilot will take place in homes across France, Poland, and the Netherlands to test out the technology.