Storage in Sand: A New Frontier in Green Energy

As the world races to cut carbon emissions and move toward renewable energy, one of the toughest challenges has been finding reliable ways to store surplus energy. While lithium-ion and hydrogen storage are the talk of the town, a surprising contender has begun to make waves in the field: sand-based energy storage.

How do they work?

Instead of storing electricity, sand batteries store heat. The process of doing so is simple, yet remarkably effective:

• Surplus energy from renewable sources (such as wind and/or solar) is converted into heat

• This heat is used to warm a silo filled with sand and/or crushed soapstone to temperatures around 500-600 °C

• The heated sand holds energy for months with minimal losses

• The stored heat is transferred to water pipes, which then supply district heating systems (These are the networks that provide hot water and heating for homes and businesses)

By storing the excess energy as heat instead of electricity, sand batteries create a practical solution for heating, particular in places with colder climates.

What are the benefits of this?

• De-carbonizing heating: Heating accounts for a significant portion of global carbon emissions, especially in colder countries. Sand batteries offer a way to replace coal, oil, and gas boilers, cutting emissions dramatically

• Cheap and scalable: Sand/crushed soapstone is inexpensive, abundant, and free from the supply bottlenecks associated with lithium. This makes the technology both scalable and affordable

• Long term storage: Unlike their chemical counterparts, sand batteries can hold heat for months at a time, bridging seasonal gaps between renewable energy supply and demand

• Durability: Since the sand does not degrade significantly over time while withing the silos, these systems could operate for decades with little maintenance

Real World Impacts

The first large-scale commercial sand battery was installed in Kankaanpää, Finland, in 2022. Early results have been impressive, with reports of around a 70% reduction in heating emissions for the local district heating network. Expansion plans are already underway in the Netherlands and Germany as well, signaling growing interest in the technology and it’s potential.

The Limitations

• Not for Electricity: While their energy storage efficacy is high, converting from the stored heat back to electricity is highly inefficient, making sand batteries unsuitable for general power storage

• Infrastructure Requirements: The technology relies on district heating systems to transfer and make use of this energy, so regions without them will not benefit directly

• Slow to roll out: Large infrastructure projects like implementing sand batteries take time, funding and approval from political leaders in order to be successful and securing these can take significant amounts of time.

A Game Changer for the Environment

While sand batteries won’t replace lithium-ion or hydrogen for electricity storage, they are a game changer for heating and storing energy as heat. By leveraging a cheap, durable, and scalable resource, they provide a powerful tool in the fight against climate change and a glimpse of how unconventional solutions can reshape the energy storage landscape.