In countries with harsh winters, such as European countries, water heating and heating systems are a necessity and represent a large energy consumption and a source of greenhouse gas emissions, especially during using gas to generate heat.
The fight against climate change and the war in Ukraine, which threatens Russia’s gas supply to Europe, have made solutions for heating with renewable energy sources even more urgent. And two Finnish companies have contributed technology that can help in this regard.
Polar Night Energy and Vatajankoski have built the world’s first functional sand battery, capable of storing heat generated by solar and wind sources, at low cost and generating low greenhouse gas emissions.
The battery operates at a power plant in the city of Kankaanpää, Finland, and is connected to the local heating network, serving around 10,000 people.
According to Polar Night Energy, the company that developed the battery, the technology solves one of the obstacles to the use of renewable energies: the need to store the energy generated by clean sources, during periods without sunlight. or no wind. This need is especially great in winter, when people in cold countries depend on heating.
According to Markku Ylönen, co-founder and CTO of Polar Night Energy, lithium batteries used in vehicles are not viable solutions for the high demand for heating systems. “If we are talking about gigawatt hours or terawatt hours of excess electricity, it is technically not possible to try to cover that with lithium batteries which would have huge costs,” he explains.
“Even if we mined all the lithium in the world, we wouldn’t be able to build batteries big enough to handle all the fluctuations in renewable energy production,” Ylönen added.
The sand battery, on the other hand, is capable of storing heat for weeks or even months, according to the company. The team converts electricity generated from renewable sources into heat that is captured from the sand-heated air, using an industrial version of a resistance heater.
The sand can reach temperatures of 500°C and maintain this temperature for months, inside a steel tank. To take advantage of this heat, the reverse process is performed, heating sand, air or water in homes or commercial establishments.
Besides the use of clean energy and the low emission of greenhouse gases, another advantage is the reduced cost of the technology, since sand is a relatively cheap and accessible material. According to Ylönen, the biggest expense of the system is the equipment and the construction of the storage tank.
As the sand does not need to be the same sand used in the production of concrete and glass, finer and of higher quality, there is always the possibility of reusing the discarded sand in civil construction or even “sand-like materials”, according to Polar Nuit. Energy.
The battery used at Kankaanpää is four meters in diameter, seven meters high and contains 100 tonnes of sand, but the company is already planning to build larger batteries, up to 20 meters in diameter and 10 meters high.
This would give the new battery a storage capacity of one gigawatt hour, or the equivalent of one million kilowatt hours (kWh). To give you an idea, it is estimated that a UK household uses an average of 1,000 kWh of gas and 240 kWh of electricity per month. Another possibility for the future is to use several sand batteries of standardized size to serve the population of larger cities.
It is important to note that with this technology, the sand battery is only used to provide heat and not electricity, which would require a more complex conversion process.
But Ylönen stresses that meeting global warming needs is a big step towards tackling climate change. “The heating sector accounts for something like a quarter or a third of global emissions,” Ylönen said.
Considering that with the ability to store around 500°C for long periods of time, the sand battery can also be used in industrial processes in the future.