‘Freeze-thaw’ battery can store energy for months in huge boost for renewables

Breakthrough marks major step towards ‘seasonal battery solution’

A ‘freeze-thaw molten salt’ battery could provide seasonal energy storage (Getty Images)

Scientists have created a new type of molten “freeze-thaw” battery that can hold energy for several months without losing charge.

The breakthrough could have major implications for the renewable energy sector, where electricity generation can fluctuate massively depending on the season.

A team from the US Department of Energy’s Pacific Northwest National Laboratory (PNNL) described the long-duration grid battery in a paper published in the journal Cell Reports Physical Science.

The study, titled ‘A freeze-thaw molten salt battery for seasonal storage’, explained how wind and solar power could be captured and stored for up to 12 weeks with minimal loss to storage capacity.

Implementing the battery technology on large-scale renewable setups would mean that electricity grids would not require fossil fuels to cover shortfalls during months when energy production is low.

“If any of seasonal excess can be efficiently stored, then it can be redistributed in times of need, thus further cementing the possibility of a reliable and sustainable grid based on 100 per cent renewables,” the paper stated.

The inability to store energy for a considerable length of time remains a fundamental issue with current battery technologies.

Much like a car or laptop that sits idle for several weeks, the battery steadily self-discharges until it no longer holds enough charge to perform its function.

“Longer-duration energy storage technologies are important for increasing the resilience of the grid when incorporating a large amount of renewable energy,” said Imre Gyuk, director of energy storage at the Department of Energy’s Office of Electricity.

“This research marks an important step toward a seasonal battery solution that overcomes the self-discharge limitations of today’s battery technologies.”

It works by heating up the battery to 180 degrees Celsius to charge it and then cooling it down to room temperature in order to essentially lock in the energy. When the energy is needed, the battery is then reheated to allow the energy to flow out.

Researchers said large-scale adoption of freeze-thaw molten salt batteries would also improve utilities’ ability to navigate power outages during severe weather events.

“It’s a lot like growing food in your garden in the spring, putting the extra in a container in your freezer, and then thawing it out for dinner in the winter,” said Minyuan Li, an inorganic chemist at PNNL and first author of the research paper.

The prototype of the battery is currently about the size of a hockey puck but a patent of the technology has been filed in order to further develop it at larger scales.

Read More: Solar batteries