The world's first commercial "sand battery" heating system is officially put into use

Since the Industrial Revolution, fossil energy has always been the fuel that drives human civilization forward. Even now, when renewable energy is being vigorously developed, fossil energy still accounts for more than 80% of the world's total energy consumption. Almost all machines are based on oil, natural gas and coal.

After decades of efforts, although we have found new energy sources such as nuclear power, hydropower, and wind power, it is still difficult to replace fossil energy. This is because although various non-fossil power generation methods are pollution-free, their stability is basically severely restricted by natural phenomena.

Photovoltaic power is affected by the sun, wind power is affected by the weather, and hydropower is afraid of the dry season, which results in the inability to generate electricity when needed, and also generates a lot of waste electricity. Therefore, it is extremely important to store the surplus green energy and save it for use when needed.

Speaking of storing electricity, I guess you must have thought of batteries! As one of the most common chemical energy storage methods, batteries have long been deeply integrated into every aspect of our lives. Whether it is from traditional lithium-based "big battery" devices, to flow batteries, silicon phase change batteries, molten salt batteries, iron-air batteries, gravity batteries, and carbon dioxide expansion batteries, they all have their own advantages and disadvantages in terms of efficiency, size, location, installation cost, operating cost, input and output power ratings, life, and the time that energy can be stored.

According to the British Daily Mail, a startup in western Finland has built the world's first fully functional commercial sand energy storage heating system, which is said to be able to store renewable energy for up to months at a time. If you have ever walked barefoot on a beach exposed to the scorching sun in the summer, you will definitely be impressed by the scorching sand. The solar heat stored in the sand provides inspiration for the development of a new type of battery. In Finland, a startup called Polar Night Energy has developed a new technology and built the world's first fully functional "sand battery" heating system.

The thermal energy storage system consists of a huge insulated steel cylinder that holds about 100 tons of construction sand. Energy from solar panels and wind turbines heats the sand to 500 degrees Celsius and creates hot air that circulates inside the silo. This "green" energy can be provided to the surrounding area heating system when needed, such as when there is a lack of sunlight, the temperature drops, or in winter when energy prices are too high.

Researchers at Polar Night Energy say the sand battery could provide a solution to the problem of using renewable energy to heat buildings all year round, and eventually to generate electricity. "The transition to green energy leads to huge fluctuations in available electricity, which in turn leads to a mismatch between production and consumption," Markku Ylönen, co-founder of the company, said in an interview. "This mismatch can sometimes be quite substantial, with tens of gigawatts (GW) of unavailable electricity possible."

"Our thermal storage batteries can provide a low-cost 'sink' for large amounts of energy, storing it as heat at high temperatures and using it in a usable form for industry and district heating, and even for power generation in the future," Markku Ylönen added. "The key is the scale of storage we can provide. We can store tens of gigawatt-hours of energy at a reasonable cost, and the system will not degrade significantly over time." The intensification of climate change and the rise in the price of fossil fuels have led to a surge in investment in renewable energy in recent years. However, for many green energy solutions, how to store energy obtained from environmental resources (such as wind and solar energy) for future use is a huge challenge.

Electricity generated by wind and solar power can be fed into the national grid, but the demand for electricity is constant and the supply of renewable energy is intermittent. This means that the lack of energy supply during periods of lack of sunshine and low winds must still be made up by fossil fuels. In Finland, the issue of energy self-sufficiency has become more pressing as Russia, the country's main source of electricity, has stopped supplying gas and electricity due to its recent move to join NATO. In Finland, winter generally lasts 200 days from November to April, with temperatures dropping to minus 45 degrees Celsius, and residential heating is the main energy consumption category. Tommi Eronen and Markku Ylönen, the two founders of Polar Night Energy, claim that their sand battery can store excess renewable energy generated when the grid capacity is full. Not long ago, the company installed the sand battery at the Vatajankoski power plant in Kankaanpää in southwestern Finland and connected it to the district heating network.

Ordinary batteries mostly use lithium or lithium alloys as anode materials, but the mining cost of metallic lithium resources is expensive, and the excess electricity they can hold is limited. Polar Night Energy's sand battery thermal storage system was installed at the beginning of this year and put into operation in May 2022. The battery uses the working principle of "resistance heating", that is, the electricity generated by renewable energy is heated by the resistor element, vibrating the particles inside the element to make it warmer. These resistor elements can heat the sand to more than 500 degrees Celsius, which in turn heats the air and circulates it through a series of pipes in the sand-filled thermal storage container, allowing renewable energy to be stored for months at a time.

When electricity demand is high and supply is low, the sand battery system can exhaust the hot air into a heat exchanger, where it heats water. The hot water is then pumped around the area to heat buildings for 35,000 residents. "We can provide about 200 kilowatts of electricity for heating the water pipes that run to Kancamp," says Markku Ylönen.

Hot water from the sand battery thermal storage system is mixed into the heating system, providing part of the heat energy for the entire neighborhood through the water circulation. This ratio varies with the seasons, because the load of the district heating network is highly dependent on the ambient temperature. Polar Night Energy's pilot power plant can store electricity from the existing grid, as well as electricity generated by solar panels and wind turbines. The reliable thermal storage system allows Can Compe to generate or purchase electricity at the lowest cost and then distribute heat when it is most needed.

According to the BBC website on July 4, Finnish researchers have installed the world's first functioning "sand battery" that can store green electricity for months at a time.

Developers say this could solve the problem of year-round supply, a major issue facing green energy.

The devices use low-grade sand, charged with heat generated by cheap electricity from the sun or wind. The sand stores heat at around 500 degrees Celsius, which can then be used to heat homes in the winter when energy prices are higher.

Finland gets most of its natural gas from Russia, so the war in Ukraine has put a spotlight on green energy.

The question of where to get heat and electricity is a matter of concern to politicians and citizens alike, especially with the long, cold Finnish winter ahead. However, tucked away in a corner of a small power plant in western Finland is a new technology that could ease some of the fears.

The key component of the device? About 100 tons of construction sand piled in a dull gray silo. The coarse sand may represent a simple and cost-effective way to store electricity for use when it is needed most.

Because of climate change and now rapidly rising fossil fuel prices, there has been a surge in investment in new renewable energy production. While new solar panels and wind turbines can be quickly added to national grids, these additional sources of energy also present huge challenges. The most vexing problem is their intermittent nature – how do you keep the lights on when the sun isn’t shining and the wind isn’t blowing?

Adding more renewable energy to the grid also means adding other energy sources to keep the network balanced, as too much or too little power can cause it to collapse.

The most obvious answer to these questions is large batteries that can store energy and balance energy demand as the grid becomes greener.

Currently, most batteries are made from lithium, which is expensive and can only store a limited amount of excess electricity.

But in the town of Kancamp, a team of young Finnish engineers has completed the first commercial installation of a sand battery that they believe could solve the storage problem in a low-cost, low-impact way.

"Whenever there is this much green electricity available, we want to be able to store it very quickly," said Marku Julenin, who developed the product.

The device is installed at the Vatajankoski power plant, which operates a district heating system.

Low-cost electricity heats the sand to 500 degrees Celsius through electrical resistance heating. This creates hot air that circulates through the sand via a heat exchanger.

Sand is an effective medium for storing heat, with little loss during long-term storage. The researchers say their device can keep sand at 500 degrees Celsius for months.

So when energy prices rise, the battery releases hot air to heat water for the district heating system, which is then distributed to homes, offices and even the local swimming pool.