Long-duration thermal battery developed to move remote mine sites away from diesel

Virginia-based 247Solar Inc, a spinoff of MIT that has received funding support from the US Department of Energy, developed a long-duration thermal battery with the objective of pushing for the addition of more renewables to remote mining operations than is feasible with conventional batteries.

Dubbed HeatStorE, the solution operates almost like an electrochemical battery. In this case, an inexpensive thermal storage medium — silica sand — is kept in a factory-made, shipping-size container and is heated by electric resistance coils using low-cost excess electricity, for example, from intermittent solar and wind power sources. 

Once the heating occurs, energy is stored as ultra-high temperature heat, which can reach up to 1000℃. Whenever needed, a specialized turbine reconverts the heat to electricity.  This device operates without combustion, as atmospheric-pressure air is passed through the “thermal storage” and drives the turbine to generate electricity.

By adding a combustor, the battery can also produce more dispatchable backup power, ideally using an emission-free fuel such as green hydrogen in the combustion process. This is also how the battery can provide spinning reserves. 

According to 247Solar, the approach is designed to replace traditional diesel gensets at remote mines, as it provides all-day reliable operation with higher renewables penetration and lower lifetime operating costs.

The typical storage duration is in the range of 4-20 hours, which allows for grid support and load shifting.

“HeatStorE combines two inventions that are part of 247Solar’s Ultra-High Temperature Technology Platform, the 247Solar Heat Power Turbine and the 247Solar Thermal Storage System,” Bruce Anderson, the firm’s CEO, said in a media statement. “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.” 

According to Anderson, the new thermal battery can also be used in industrial applications, as it can convert otherwise wasted hot process exhaust to electricity.