Many industrial processes run 24 hours a day, so they’ll need constant heating. By carefully controlling the heat transfer, Rondo’s system can charge quickly, taking advantage of short periods when electricity is cheap because renewable sources are available. The startup’s heat batteries will probably require about four hours of charging to be able to provide heat constantly, day and night.
A “monstrous” amount of heat
One of the major challenges for heat storage technologies will be building enough systems to meet heavy industry’s huge energy demand. The sector uses a “monstrous” amount of heat, says Rebecca Dell, senior director of industry at ClimateWorks. Of all the energy used each year in industry, about three-quarters is in the form of heat, while only one-quarter today is electricity. Industrial heat makes up about 20% of total global energy demand.
Fossil fuels have been the obvious, most economical way to power these massive industrial processes, but the prices of wind and solar power have fallen by over 90% over the past several decades. Dell says that’s opened the door for electricity to play a bigger role across industry.
“We’re at this magnificent moment where we can stop burning stuff for our heat and have it be cheaper,” O’Donnell says.
There are a few other potential options for using cheap renewable energy in industry. Some facilities could be adjusted to use electricity directly, instead of high heat. Companies are working on electrochemical processes to make cement and steel, for example, though replacing all the infrastructure in existing plants could take decades. Using electricity to generate hydrogen, which can later be burned for electricity, is another potential route, though in many cases it’s still cost-prohibitive and inefficient.
Any effort to fulfill industry’s massive heat demand will require dramatic expansions in electricity generation. A standard cement plant uses about 250 megawatts of energy, mostly in the form of heat, all the time, Dell says. That’s about 250,000 residents’ worth of power, so electrifying a large industrial facility will mean adding electricity demand equivalent to that of a small city.
One brick at a time
Rondo isn’t alone in its quest to deploy heat batteries in industry. Antora Energy, based in California, is also building heat storage systems, using carbon. “It’s super simple—it’s literally just solid blocks,” says cofounder and COO Justin Briggs.
Instead of using a separate heating element (like Rondo’s “toaster coil”) to turn electricity into heat, Antora’s system will use carbon blocks as a resistive heater, so they’ll both generate and store heat. This could cut down on costs and complexity, Briggs explains. But the choice will also mean the system needs to be carefully enclosed, since graphite and other forms of carbon can degrade at high temperatures in the air.