Finland has launched the world’s first batter made out of sand. It could help solve one of renewable energy’s biggest challenges, which is how to ensure a steady supply of power all year round. The concept behind the battery is simple. Renewably-generated electricity is converted into heat, which is pumped into a silo filled with 100 tonnes of sand.
The sand is thus heated at temperatures of up to 1000 degrees Centigrad. It can hold this temperature for months at a time. In winter, the stored energy is used to heat local homes and businesses. This technology could also provide heat for industrial processes that today rely on fossil fuel energy.
Most large batteries today are made from lithium, but this is an expensive and scarce resource. Extracting this mineral carries a significant environmental cost. The batteries can be up to hundreds of cubic meters in size, and can even be built underground.
We embrace renewable energy by providing stable and affordable heat storage sytems for district heating and industrial applications.
Finland’s Polar Night Energy
The world, however, is facing a growing shortage of sand. The designers say the battery can use low-grade sand, or even sand-like materials. Finland’s Polar Night Energy (PNE) solution converts electricity to heat, and store it for later use. Sand is used as the storage medium, which leads to safe operation and a natural balance in the storage cycle.
Inside the sand, a heat transfer system is built that enables effective energy transportation to and from the storage. Proper insulation between the storage and environment ensures long storing period, up to months, with minimal heat losses. The size of PNE storage options vary from tens to thousands of cubic meters.
CO2 emissions of our heat storage are embedded emissions from construction materials and from the construction phase. As these embedded emissions of the PNE heat storage are minor, the emissions of produced heat result mostly from the source of electricity. It can be said that the heat taken from PNE’s storage is as clean as was the electricity fed into the storage.
The solution can provide stable, affordable, clean energy to New York as well as to the distant village.
Finland’s Polar Night Energy
Heat storage is always a part of an energy system, would it be either a heating network of a single building, a large district heating network or a self-contained electricity and heating system of an island.
Each of PNE heat storages are individually tailored according to the requirements and operation logic of the customer. PNE designs both individual heat storages and full energy systems, which are designed based on simulations using COMSOL Multiphysics software. The systems are created using 3-D transient heat transport models and with real-life input and output data.
PNE designed and built the first commercial sand-based heat storage to Vatajankoski, an energy utility based in Western Finland. It will provide heat for Vatajankoski’s district heating network in Kankaanpää, Finland. The storage has 100 kW heating power and 8 MWh capacity. The full-scale utilization of the storage will begin during the year 2022.
There’s also a 3 MWh running test pilot in Hiedanranta, Tampere. It is connected to a local district heating grid and it provides heat for a couple of buildings. The pilot enables testing, validation and optimization of the heat storage solution. The energy is partly from a 100 square meter solar panel array and partly from the electric grid.
Production of renewable energy sources such as wind and solar power is highly volatile, and only partly overlapping with the consumption in time. As these volatile electricity sources increase rapidly in societies, more and more energy storages are needed. PNE’s technology provides a way to refine cheap and clean surplus electricity to valuable heat in an affordable way to be used when most needed.
