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Thermal batteries charge up

Heat batteries made from bricks from startup Rondo Energy

Heat batteries made from bricks from startup Rondo Energy. Photo: Courtesy of Rondo Energy

Thermal batteries, which store electricity as heat, are gaining traction as a competitive low carbon way to provide clean energy for industrial companies, Katie writes.

Why it matters: Industrial heat, much of it powered by natural gas, contributes to significant global greenhouse gas emissions today.

Driving the news: This week startup Antora Energy announced a $150 million funding round, led by Decarbonization Partners, a joint venture of BlackRock and Temasek.

  • Antora makes a type of battery that charges using clean energy–generated electricity to superheat coils that warm up carbon blocks in insulated containers.

State of play: Antora is one of a handful of companies emerging to use different low cost materials to store heat for potentially days.

  • Rondo Energy, which uses brick and iron wire to store energy, took in a $60 million round last year from investors including Breakthrough Energy Ventures, Microsoft's Climate Innovation Fund, and Rio Tinto.
  • Electrified Thermal Solutions, which developed firebricks at MIT to store energy, is working with industrial partners 3M and Amy's Kitchen on deployments and has funding from the Department of Energy's ARPA-E program.
  • Caldera is using recycled aluminum and rock to store energy and plans to build a factory to commercially produce thermal batteries.
  • Brenmiller Energy, which uses crushed rocks to store energy, built a thermal battery-based co-generation station at the State University of New York (SUNY) Purchase.
  • Fourth Power makes a thermal energy system using graphite and molten tin.
  • RedoxBlox makes a thermochemical battery out of metal oxide pellets made of low-cost earth-abundant materials.

Big picture: Thermal batteries are attracting industrial customers and investors because they have the potential to be both low cost and low carbon, replacing the use of natural gas for heat.

  • "Thermal batteries can be cost-competitive with natural gas in much of the US even today," according to a report in October from the Renewable Thermal Collaborative, working with the Center for Climate and Energy Solutions and The Brattle Group.
  • However, the cost to make the carbon-free heat is highly dependent on details of the region: the local electricity supply, regional access to wholesale power prices, and eligibility for state or city policy support.

What's next: These startups are mostly at the early stages of deploying pilot projects, and they'll need to grow production and cross the manufacturing valley of death.

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