Finnish researchers have created a heat battery – which can store heat for months at a time. A huge pile of low-grade sand (about 100 tonnes) is heated up to around 500°C, using green energy in the summer months, when energy demand is low. This power is used (through resistive heating) to generate heat, this heat is then circulated into the sand, through a heat exchanger.
Months later, the sand can then be used to heat water in pipes, which can be used to warm buildings.
Now, one downside is that thus far, this heat cannot be turned into electricity in an efficient way.
However, this could be a game changer. Imagine each housing estate having one of these buried in the middle of the estate. During the summer months, excess electricity can be used to heat up the sand – cheapest going, or indeed using sand with negative prices when there is too much electricity available. Through careful management, this heating can be done cheaply (or even free if many of the houses have solar panels). This huge heat battery, can then be used to heat the whole estates water – year round, and heat the homes through the cold winter months. Given that estates tend to range from a few dozen houses, up to thousands, each battery could cut carbon emissions by several hundred, to tens of thousands of tonnes of carbon.
Importantly, this may be the missing link for going carbon neutral – and eliminating gas from space heating without dramatically increasing peoples heating bills. Whatever happens, we need the Finnish team to commercialize their design quickly, so that we can use it worldwide within a few short years.