Firebrick heat storage for industrial processes would substitute for about 14% of battery capacity worldwide by 2050 in a 100% renewable energy system, compared to a base case without firebricks, projects a study by Stanford professor Mark Jacobson and three Stanford colleagues.
Firebricks are made from common materials, and the cost of a firebrick storage system is less than one-tenth the cost of an equal-capacity battery system, the study says. Firebricks may be heated to high temperatures with external resistance heaters, while a type of firebricks that are electrically conductive may be heated with an electric current that dissipates to heat.
The U.S. Department of Energy may provide up to $75 million to support two firebrick heat storage projects, saying the technology is “highly replicable.”
Firebrick systems powered by renewable energy could be used for up to 90% of industrial process heat applications, the Stanford study says. Meeting that demand in the U.S. would require firebrick system capacity of 2.6 TWh, with a peak discharge rate of 170 GW.
Producing industrial heat with renewables would reduce industrial combustion emissions, which are currently 9.6% of U.S. all-sector emissions.
Globally, firebrick systems for industrial process heat could reach 2,100 GW of maximum power discharge capacity under a 100% renewable energy system, the study projects.
At that scale, firebrick systems would not only substitute for 14% of battery capacity but would also reduce annual hydrogen production for grid electricity by about 31% and underground heat storage capacity by about 27%.
Cost comparison
The present value cost of firebrick heat storage capacity will be $6/kWh of equivalent electricity over the 2020 to 2050 period, the study says.
That cost projection begins with a projected 2035 cost for a battery system. An installed battery pack will cost about $60/kWh, or $240/kW for 4-hour batteries, by 2035, the study projects, and uses that value for the time period from 2020 to 2050. The study notes that prices in 2035 may actually be lower than $60/kWh, citing a report that lithium-iron-phosphate battery pack prices from Chinese producers CATL and BYD were about $56/kWh last January.
The study next uses an estimate from firebrick system developer Rondo Energy that the cost per kWh-thermal of a firebrick system will be about one-tenth the cost per kWh-electricity of a battery system.
Because one-tenth of $60 is $6, the study uses in its analysis a $6/kWh cost for firebrick systems.
The study also cites a 2019 study saying that preliminary cost estimates at that time indicated a firebrick system cost near $10/kWh.
The open-access article, published in PNAS Nexus, is titled “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.”
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If you want solar industrial process heat why collect it with expensive 20% efficient solar cells when it is much cheaper and more efficient to collect solar heat directly. If you want solar electricity than storing heat and converting the heat back into electricity loses half of more of the captured solar electricity due to conversion inefficiencies. This would more than double the cost per kWh of solar electricity. Direct storage in batteries is cheaper. Making solar electricity and storing it as heat is unlikely to be useful even if the storage medium is free.
I assume those dollars per kilowatt hour are $ per kilowatt hour of installed capacity, not dollars per kilowatt hour provided, which would be outrageously expensive. It might be good to make that clarification in the article to avoid casual readers using this as an argument (incorrectly) the renewables are ridiculously expensive.