For thousands of years, people have used special heat-resistant bricks to line kilns, furnaces and other hot enclosures. In a new study published in the journal PNAS Nexus, researchers from Stanford University say that these same firebricks could be an inexpensive way to store electricity generated by wind turbines and solar panels.
The researchers propose using excess renewable electricity to produce heat for storage in firebricks. The bricks could then continuously provide heat for industrial processes at low cost. Computer simulations for 149 countries show that using firebricks could significantly cut the cost of transitioning to clean energy.
Batteries are the most common technology for storing renewable electricity for later use when the sun isn’t shining or wind isn’t blowing. But about 17% of global carbon emissions come from burning fossil fuels to produce heat for industrial processes such as making cement and steel.
Producing heat from renewable electricity could almost eliminate these heat-related emissions. So storing renewable electricity as heat in various materials such as salts, oils, bricks and rocks is gaining traction. Some companies are starting to commercialize thermal storage technologies.
Firebricks can store electricity for one-tenth the cost of batteries, according to Mark Jacobson, a professor of civil and environmental engineering at Stanford and lead author of the study. “The materials are much simpler too,” he said in a press release. “They are basically just the components of dirt.”
The idea is to have stacks of firebricks in an insulated container to store heat. The heat is released when needed by passing air over the firebricks.
The Stanford team set out to analyze the impact of firebrick heat storage in 149 countries that are responsible for 99.75% of global carbon dioxide emissions from fossil fuels. In their computer simulations, they imagined a hypothetical future where each country has transitioned fully to wind, geothermal, hydropower, and solar.
With the computer models, the researchers compared costs, emissions, health impacts, and land needs for two scenarios. In one, firebricks provide 90% of industrial process heat, and in the other there is no form of thermal energy storage. Instead, heat would come from electric furnaces, boilers, and heat pumps, with batteries storing electricity for those machines.
The use of firebricks reduced battery capacity by about 14%, annual hydrogen production for grid electricity by about 30%, and underground heat storage capacity by about 27%. It also reduced onshore wind capacity, land needs, and overall annual energy cost. Overall, the scenario with firebricks cut capital costs of the energy transition by $1.27 trillion.
“Every bit of combustion fuels we replace with electricity reduces air pollution,” Jacobson said. “And because there is a limited amount of money to transition at a high speed, the lower the cost to the overall system, the faster we can implement it.”
Source: Mark Z Jacobson et al. Effects of firebricks for industrial process heat on the cost of matching all-sector energy demand with 100% wind–water–solar supply in 149 countries. PNAS Nexus, 2024.
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