How Dirt Batteries Could Power the Energy Transition
The Trump administration is attempting to breathe new life into the nation’s declining coal industry, but greater market forces indicate that the dirtiest fossil fuel will likely continue its terminal decline. Though the sitting president has signed an executive order aimed at “Reinvigorating America’s Beautiful Clean Coal Industry,“ there are zero new coal plants under construction as utilities “continue to prioritize adding renewables, batteries, gas and nuclear power ahead of new coal-fired capacity based on the cost and efficiency.”
It’s undeniable that the domestic coal industry is aging out. “There’s been six times more coal power plants retired than constructed in the U.S. this century, which underscores the scope of the challenge facing even the most ardent coal bulls as they try to engineer an industry revival,” Reuters reports. Experts agree that the United States coal industry peaked about two decades ago, as lowering prices for natural gas and solar rendered the industry obsolete.
But energy industry insiders think that there may be new life coming down the pike for decommissioned coal plants. However, that new life will not contribute to the United States’ fossil fuel renaissance, but instead to the stymied but ongoing clean energy transition. A team of researchers at Stanford University is working on turning retired coal plants into energy storage facilities by taking advantage of the plants’ turbine blades and connected generators.
The plan involves storing thermal energy – heat – in giant piles of dirt alongside this leftover, formerly coal-fired infrastructure. “Most dirt includes naturally heat-resistant materials, such as silicon dioxide and aluminium oxide,” reports New Scientist. Industrial heaters within the insulated dirt pile can maintain temperatures of about 600° Celsius (1,112° Fahrenheit). When renewable energy sources create a surplus of energy, that extra energy can be stored as heat until it is needed on the grid, at which point it would be piped out via steam, which would then turn a turbine to create electricity.
While it may sound too low-brow (a pile of dirt?) to be a real energy solution of the future, the plan has real-world precedent. In Finland, two similar batteries – stored in heaps of sand rather than dirt – are already up and running, and providing energy and heat to whole towns in the dead of Nordic winters. “With high specific heat, low thermal conductivity, and no risk of fire, sand-based energy storage systems are gaining traction in grid-scale and industrial heating applications,” Interesting Engineering reported earlier this month. This assessment would certainly extend to dirt batteries.
One of the critical benefits of these battery types is that they are ridiculously cost-effective. As New Scientist reports, perhaps unnecessarily, “dirt is cheaper, more abundant and more widely available than other types of long-term energy storage, such as lithium batteries or hydrogen fuel.”
Another key benefit is that repurposing shuttered coal plants as energy storage centers could bring much-needed jobs and tax revenue to coal country and contribute to a just transition in which fossil-fuel-dependent local economies are not left behind.
If developed intentionally and with a just transition in mind, energy storage projects would not merely function as a bandaid over much bigger economic issues in coal country – they could serve as a real lifeline. As of 2022, the energy storage market was valued at $198.8 billion. Allied Market Research estimates that this will climb to $329.1 billion by 2032, with a compound annual growth rate of 5.2% from 2023 to 2032.
By helping to align energy supply and demand as variable energy sources become more dominant in local and national energy mixes, energy storage is critical to energy security as well as the industry bottom line. Due to its central role in decarbonizing energy grids, energy storage is heating up to be “clean energy’s next trillion-dollar business.” All of this means that storage on unused coal plants while taking advantage of existing infrastructure is a no-brainer, especially when the required materials come dirt cheap – literally.
