Could Hot Rocks Help Solve the Climate Crisis?

An anonymous reader shared this report from CNN: "(The rocks) in the box right now are about 1,600 degrees Celsius," Andrew Ponec said, standing next to a thermal battery the size of a small building. That is nearly 3,000 degrees Fahrenheit, "Hotter than the melting point of steel," he explained. But what makes his box of white-hot rocks so significant is they were not heated by burning tons of coal or gas, but by catching sunlight with the thousands of photovoltaic solar panels that surround his prototype west of Fresno. If successful, Ponec and his start-up Antora Energy could be part of a new, multi-trillion-dollar energy storage sector that simply uses sun or wind to make boxes of rocks hot enough to run the world's biggest factories. "People sometimes feel like they're insulting us by saying, 'Hey, that sounds really simple," Ponec laughed. "And we say, 'No, that's exactly the point'... The problem is you can't shut down your factory when the sun goes behind a cloud or the wind stops blowing, and that's exactly the problem that we focused on." While the word "battery" most likely evokes the chemical kind found in cars and electronics in 2023, hot rocks currently store ten times as much energy as lithium ion around the world, thanks to an invention from the 1800s known as Cowper stoves. Often found in smelting plants, these massive towers of stacked bricks absorb the wasted heat of a blast furnace until it heats to nearly 3,000 degrees Fahrenheit, and then provides over 100 megawatts of heat energy for about 20 minutes. The process can be repeated 24 times a day for 30 years, and Antora is among the startups experimenting with different kinds of rocks in insulated boxes or molten salt in cylinders to find the most efficient combination... Antora has managed to raise $80 million in seed money from investors that include Bill Gates, but their main competitor is another Bay Area startup called Rondo that uses abundant refractory brick, which is cheaper than carbon by weight but not as energy dense. Rondo has attracted even more funding than Antora and its first battery is producing commercial power for an ethanol plant in California... Tesla recently predicted a carbon-free world will need an astonishing 240 terawatt-hours of energy storage - more than 340 times the amount of storage built with lithium-ion batteries in 2022. Rondo CEO John O'Donnell predicts more than half of all that new capacity will come in the form of heat batteries, simply because the raw ingredients are so readily available. By plugging their factories into as many thermal batteries as they need, manufacturers won't have to wait in a years-long line for grid connections and upgrades. Ponec tells CNN that when it comes to de-carbonizing today, "we have the tools we need. We just need to deploy them. "The transition is inevitable. It's going to happen. And if you talk behind closed doors to most of the people in the fossil fuel industry, they'll say the same thing."

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