A new thermal battery from 247Solar Inc, a business with origins at the Massachusetts Institute of Technology (MIT), is set to help miners incorporate more renewable energy sources into the power mix at their remote operations.

The HeatStorE™ long duration thermal battery operates almost like an electrochemical battery but has significant advantages at longer durations, according to 247Solar.

“The basic principle of the thermal battery is rather simple,” the company explained. “Electric resistance coils heat an inexpensive thermal storage medium (silica sand) using low-cost excess electricity, eg from intermittent solar and wind power sources. Energy is stored as ultra-high temperature heat (up to 1,000°C) – at a fraction of the cost of batteries.”

Whenever needed, a specialised turbine reconverts the heat to electricity in this process, according to 247Solar. This turbine can generate electricity without combustion, as atmospheric-pressure air is passed through the ‘thermal storage’ and drives the ‘turbine’ to generate it.

By adding a combustor, the battery can also produce even more dispatchable back-up power, ideally using an emission-free fuel such as green hydrogen in the combustion process, 247Solar says.

“This is also how the battery can provide spinning reserves,” it said. “The innovative approach is designed to replace traditional diesel gensets at remote mines, as it provides 24/7 highly reliable operation with higher renewables penetration, significant fuel savings, and dramatically lower lifetime operating costs.”

Bruce Anderson, 247Solar’s CEO, said: “HeatStorE combines two inventions that are part of 247Solar’s Ultra-High Temperature Technology Platform, the 247Solar Heat2Power™ Turbine and the 247Solar Thermal Storage System. Combining these two proven technologies ensures that HeatStorE is also extremely reliable.

“We expect more than 20-year operations with little or no performance degradation.”

This new approach consists of a factory-made, shipping-size container filled with sand that is heated by resistance coils. It also comes with low operating and maintenance costs, according to the company.

“The combination of robustness and life-cycle cost advantages will enable mining companies to implement new power plant concepts with fewer diesel engines – ultimately without any at all,” 247Solar said.

The typical storage duration of HeatStorE is in the range of 4-20 hours, which also allows for substantial grid-support and load shifting. The cost per kWh drops rapidly with duration, it claims. Behind the meter in industrial applications, the battery can also convert otherwise-wasted hot process exhaust to electricity.