Another Kind of Battery Is Charging Up

Oakland-based Rondo Energy, which stores heat in bricks at temperatures it says can be high enough for steelmaking, just raised $60 million. Rondo and its partner, Siam Cement Group, are expanding a factory in Thailand to make more of its batteries, which are in use at a biofuels plant in California.

Heat batteries work by passing current through a resistor, like a toaster element, to heat some material that can stay hot for days in a container. Companies use bricks, rocks or molten salt. Air or liquid is later passed through the container to release heat, in some cases above 2,500 degrees Fahrenheit, that can be used in a factory.

Continue reading this article by Ed Ballard here by WSJ.