The biggest problems you hear about with batteries are cost, and availability. Starting with the recent popularity of electric vehicles and continuing with the growing popularity of grid storage, the price and availability of metals like lithium have become prohibitive for some applications. But sometimes there are cheaper alternatives.
In Pornainen, Finland, residents are using a 2,000 metric ton silo of crushed soapstone (essentially sand) as a heat battery. Heat is stored in the sand, and then released when its needed. The battery can hold enough heat to supply the 5,000 residents of the town for a month in the summer, and for a week in the winter. Like other batteries being employed, the sand battery gets its energy from solar and wind power and stores it for later. Sam Meredith explains at CNBC:
Essentially, the sand battery technology operates as something akin to a giant thermos with heat-storing material.
The first step is to get electricity off the grid when there is plenty of wind or solar power, before then heating up the sand to very high temperatures. The heavily insulated silo keeps that heat trapped for days or weeks before being discharged via heat exchangers to warm water for the local district heating network.
“Three steps — and the key to the whole thing is the sand enables you to have a delay between the time you use electricity, and you use the steam,” Polar Night Energy’s Chief Commercial Officer Annette Höglund-Dönnes told CNBC by video call.
“That delay is your business advantage because you can heat up the sand when the electricity is cheap, and you use the steam when normally it would be very expensive to produce steam off the grid, which is the daytime when everybody else is using it,” she added.
The builder of the sand battery, Polar Night Energy, explains its operations in the videos below:
It seems fairly simple. Heat up sand, use that heat later to heat your home. Many people are doing some do-it-yourself versions of the sand batteries at home. Scott from Everyday Solar explains the basics in the video below:
Action Line: Should you build your own sand battery at home? That depends on your technical skill, and don’t do anything you’re not fully prepared for. But you should consider putting power away in the pantry with professional help if necessary. Click here to subscribe to my free monthly Survive & Thrive letter.
Read the entire series here.
