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Firebrick heat storage technology, not batteries, will be used to store energy for industrial process heat in a 100% renewable energy system, says a study out of Stanford University.
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, according to 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 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 a 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 period from 2020 to 2050. The study notes that prices in 2035 may 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 nearly $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.” |
