In Finland large number of homes are heated by district heating. This means there is heat plant or combined heat and power (CHP) plant, which heats water to around 70C - 110C (158F - 230F) and that is distributed to homes.
In this system heat batteries are useful, and near all CHP plants in Finland have done heat battery in last few years. These heat batteries are just 7-store high insulated water storage. Usefulness to store just water is that system is relatively simple. Water in - water out. This makes it that the turbine in CHP can be run more freely towards electricity price, not the network heat demand.
Plain heat plants generally don’t yet have these, because the buffer created by heat battery is not that much needed. But if these sand batteries can store heat longer, and because they might be cheaper to build, it can make sense.
Source: I work in company that owns 19 district heating networks.
Adding little bit extra context here.
In Finland large number of homes are heated by district heating. This means there is heat plant or combined heat and power (CHP) plant, which heats water to around 70C - 110C (158F - 230F) and that is distributed to homes.
In this system heat batteries are useful, and near all CHP plants in Finland have done heat battery in last few years. These heat batteries are just 7-store high insulated water storage. Usefulness to store just water is that system is relatively simple. Water in - water out. This makes it that the turbine in CHP can be run more freely towards electricity price, not the network heat demand.
Plain heat plants generally don’t yet have these, because the buffer created by heat battery is not that much needed. But if these sand batteries can store heat longer, and because they might be cheaper to build, it can make sense.
Source: I work in company that owns 19 district heating networks.