Finnish Metropolis Inaugurates 1 MW/100 MWh Sand Battery

August 30, 2025

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There are extra methods to retailer power than simply utilizing batteries. Some are utilizing hearth bricks, notably for course of warmth for industries that depend on excessive warmth in manufacturing. Others suggest an association of huge concrete blocks that transfer up and down just like the weights of a large grandfather clock, changing kinetic power to potential power and again once more. In Finland, two intrepid engineers started experimenting with a sand battery a number of years in the past.

As we reported when the primary prototype was unveiled three years in the past, the thought of a sand battery started with two Finnish engineers, Markku Ylönen and Tommi Eronen. The idea is simplicity itself. Make a extremely large pile of sand. Warmth it with extra renewable electrical energy to round 500°C (932°F), then use that warmth later to warmth properties, factories, even swimming swimming pools. They are saying the sand can keep sizzling for 3 months or extra. The pair have based Polar Night time Vitality, which constructed a prototype consisting of 100 tons of sand inside what seems like a silo within the city of Kankaanpää.

Many Individuals are unfamiliar with the idea of district heating, however it’s broadly utilized in different counties, particularly in Scandinavia the place preserving faculties, municipal buildings, arenas, factories, and houses heat in winter is a problem.

Loviisan Lämpö is a Finnish district heating firm that provides district heating to prospects in Loviisa, Pukkila, Pornainen, and Pyhtää. It has collaborated with Polar Night time on a brand new sand battery — one that’s a lot bigger than the prototype — which started working within the metropolis of Pornainen in southern Finland this month, the place it’s anticipated to scale back carbon emissions from district heating by 70 p.c.

Beforehand, nearly all of warmth wanted for the system got here from burning oil, however that has now been utterly eradicated. The system will proceed to burn wooden chips to complement the sand battery. Wooden chips are a minimum of carbon impartial, though not a perfect answer because it takes years for bushes to develop however solely minutes for the chips to burn.

On the commissioning ceremony for the brand new battery, Mikko Paajanen, CEO of Loviisan Lämpö, mentioned, “A few years in the past, we began contemplating how one can take district heating in Pornainen to the subsequent degree. It could have been straightforward to easily change the outdated wooden chip energy plant with a brand new one of many identical type, however that didn’t align with our targets. We evaluated each potential various, and the Sand Battery proved to be the best choice.”

The battery is a 42 foot tall, 50 foot broad metal cylinder stuffed with 2,000 tons of crushed stone. In keeping with Quick Firm, when additional renewable electrical energy is on the market, the system makes use of it to warmth up the crushed stone, the place it’s saved till wanted. Then the warmth from the battery travels to different buildings via a system of pipes stuffed with sizzling water. Every constructing has its personal tools to distribute the warmth to radiators, flooring heaters, or different heating units.

“Now we have already learnt that our system has much more potential than we initially calculated. It’s been a constructive shock,” mentioned Ylönen after the prototype was positioned in service. “At any time when there’s a excessive surge of accessible inexperienced electrical energy, we wish to have the ability to get it into the storage actually shortly.” The necessity to use power extra properly was pushed house for Finns after Russia stopped offering electrical energy, methane, and oil to Finland when it voted to affix NATO. Finland and Russia share a standard border.

Sand Battery Is Easy & Environment friendly

The sand battery is simplicity itself. “We simply warmth air and [circulate it] via sand,” says Liisa Naskali, COO of Polar Night time Vitality. However supplies apart from sand can be utilized. The brand new battery truly makes use of crushed soapstone chips from an area fire producer. Sand, or different materials crushed into sand-size particles, has the flexibility to retailer warmth for weeks. In contrast to another batteries, the system doesn’t depend on chemical substances, doesn’t degrade, and gained’t catch on hearth. In operation, the sand battery has demonstrated a spherical journey effectivity of 90 p.c.

Contained in the metal tank, a warmth exchanger and a closed loop system are used to flow into the warmth. Software program runs heaters when electrical energy costs are low. Up to now this summer season, the district heating operator has paid solely about 10 p.c of the common value of electrical energy as a result of heating the system solely occurred at optimum instances. That helps make the expertise price aggressive, though the preliminary set up price is pretty excessive.

Polar Night time is now in talks with different district heating corporations and manufacturing facility homeowners with a necessity for prime temperature course of warmth. For the corporate, the venture in Pornainen is a essential proof level. “That is actually essential for us as a result of now we are able to present that this actually works,” a spokesperson for Polar Night time mentioned.

Funding Alternatives

Polar Night time and its companions see a brilliant monetary future for sand batteries as a result of they’ll take part in electrical energy reserve markets, cut back dependence on single power sources in warmth manufacturing, and function a superb instance of sector integration between electrical energy and warmth.

“For us, the sand battery is a superb industrial funding, however we additionally wished to boldly help an modern answer that advantages prospects, the municipality, and the whole electrical energy market. This can be a concrete instance of a value environment friendly and sustainable funding. If it really works right here, it’ll work wherever,” mentioned Sauli Antila, the funding director at CapMan Infra, the company proprietor of Loviisan Lämpö.

The profitability of the sand battery relies on charging it in accordance with electrical energy costs and Fingrid’s reserve markets. Its massive storage capability permits balancing the electrical energy grid and optimizing consumption over a number of days and even weeks. The reserve market operations and optimization of the Pornainen Sand Battery are managed by the software program unit division of Elisa Industriq.

“The Pornainen plant might be adjusted shortly and exactly, and it additionally has a remarkably lengthy power buffer, making it properly fitted to reserve market optimization. Our AI answer robotically identifies the perfect instances to cost and discharge the Sand Battery and allocates flexibility capability to the reserve merchandise that want it most. Steady optimization makes it a genuinely worthwhile funding,” defined Jukka-Pekka Salmenkaita, vice chairman of AI and particular initiatives at Elisa Industriq.

Polar Night time has a transparent imaginative and prescient for the longer term. Building of an electrical energy manufacturing pilot will start within the coming weeks in Valkeakoski, Finland, and the corporate is in energetic negotiations for a number of large-scale thermal storage initiatives in district heating, sizzling air, and course of steam manufacturing. “Industrial purposes are notably promising, particularly the place warmth above 100°C is required, one thing electrical boilers and warmth pumps can not present,” mentioned Polar Night time COO Liisa Naskali.

This expertise isn’t going to exchange grid-scale battery storage, however might be helpful in lots of conditions the place battery storage is just not. A touch upon the YouTube video beneath complained, “Not a phrase about return on funding within the presentation. Which means it’ll by no means repay. They simply wasted taxpayers’ cash to stroke their very own egos.” MAGAlomaniacs are all over the place today.