Amid the hum and heat of a Berlin thermal power station stands a shining, modern contraption. Its pipes and vats contain a common yet unique substance. Researchers are testing a type of salt—though not the common table variety—to store heat and quite possibly change the future of power generation.
Energy company Vattenfall operates the Reuter plant, which supplies 600,000 Berlin households with heat. Vattenfall and Swedish start-up SaltX are experimenting with a simple chemical reaction. It occurs when plentiful, God-created calcium oxide, or “quicklime,” gets wet. When that happens, quicklime’s salt-like grains soak up the water and release large amounts of heat.
The SaltX process basically mirrors how batteries work. But instead of storing electricity, the system stores heat. Later, removing the water—through a practice rather like baking—turns the substance back into calcium oxide. Calcium oxide can be safely recycled. This gives it an edge over some battery technologies that use rare or extremely toxic materials.
Hendrik Roeglin oversees the salt storage project for Vattenfall. The company can currently store enough energy to heat about 100 large homes. The facility could be expanded. It could potentially heat all the homes and offices already connected to Berlin’s district heating system.
“It makes total sense to try this because, storing energy is a hugely important step in the future,” says energy economist Kai Hufendiek.
The salt energy system could help solve the renewable energy problems of wind and solar. These sources are unreliable. Sometimes they generate too much power . . . but mostly too little.
Of course, quicklime will not solve all of Germany’s energy woes. Most experts agree that a range of solutions will be necessary for the country to replace fossil fuels.
Germany’s plan is known as the Energiewende, or “energy transition.” It seeks to be environmentally sound, reliable, and affordable.
Phasing out nuclear, coal, and gas is ambitious for an industrial country like Germany. Yet its government has set a deadline to close the country’s nuclear plants by 2022 and stop burning coal for electricity by 2038. Replacing gas will take longer. Scientists hope to rely completely on renewable technology sometime around the middle of the century.
Roeglin, the engineer, is waiting until the end of the year to see how quicklime performs. “It may,” he says, “be one part of the puzzle.”
In the days before electricity, theaters heated calcium oxide to create “limelight,” an intense glow, to illuminate their productions.