Researchers believe they can turn millions of homes in Europe off gas in the near future, after inventing a “heat battery” based on salt and water.
The Eindhoven University of Technology team say their compact and inexpensive battery system is ready for real-world testing and will be “revolutionary for the energy transition.”
The heat battery is based on an old thermochemical principle, which is that when water is added to salt, heat is produced. The reverse is also possible, whereby heat can be used to evaporate the water, thus storing the thermal energy within the salt.
The storage of heat within the dry salt makes the battery completely loss-free, offering an incredibly efficient way to store energy for future use. This is particularly useful when the energy supply comes from renewable sources, such as wind and solar, which tend to fluctuate significantly and therefore require gas or other sources to supplement them.
It took 12 years to develop and create a battery design that could actually work at scale, and the researchers say it comes at a critical time as European countries look to free themselves of Russian gas following the invasion of Ukraine.
The source of heat to store in the salt can be taken from industrial by-products, such as residual “waste heat” in factories or surplus heat from data centers.
“If industrial waste heat could be used to heat homes, we would have a win-win situation: homes could become independent of gas – an even more urgent need given the dependence on Russian gas – and CO emissions2 would be reduced,” the Eindhoven University of Technology said in a statement.
The system is composed of a heat exchanger, a fan, an evaporator/condenser and a boiler with salt particles. Despite its simplicity, the proof of concept was able to provide heating for an average family of four for two days.
Engineers have since upgraded this to a fully functional prototype, about the size of a large cabinet, that could be used in the real world. With almost 30 times the storage capacity, the system could heat a house for up to two months.
“It’s not a product yet, but now everything is ready to be tested for the first time in a real-world situation,” said Olaf Adan, a professor at Eindhoven University of Technology.
“While the potential is great, we have also seen many technologies with great potential that have not achieved it. So let’s keep our feet on the ground and take it one step at a time.”
A pilot is already being set up to test the technology later this year in homes in France, Poland and the Netherlands.
If successful, Professor Adan claims it could be used to phase out gas use in millions of homes in the near future.
“In the Netherlands we have around 150 Petajoules [un número con 15 ceros] of waste heat from industry per year,” he said.
“That would allow almost 3.5 million households to be cut off from gas, which is more than double the Dutch government’s target of 1.5 million households without gas by 2030.”