This sponsored article is dropped at you by COMSOL.
As we attempt to objectively research nature, we are sometimes reminded of how pure forces have an effect on us personally. We can sit at a desk and contemplate warmth in its varied varieties, however we could be distracted if our toes are chilly! When we flip up the warmth in our properties and workplaces, we should steadiness our private want for heat with the worldwide impression of burning fossil fuels like oil, fuel, coal, and biomass. Anthropogenic local weather change confronts humanity with a problem: How can we preserve heat now as we attempt to stop our world from overheating sooner or later?
It is a frightening query {that a} startup referred to as Polar Night Energy, within the small and chilly nation of Finland (Figure 1), is making an attempt to reply. In a area identified for lengthy, darkish winter nights, Polar Night Energy is constructing a system within the metropolis of Tampere that may warmth buildings with saved photo voltaic vitality — all day, all evening, and all winter lengthy. The obvious contradictions don’t finish there. In an period of complicated cleantech options, usually constituted of uncommon and costly supplies, Polar Night Energy’s warmth storage and distribution system consists of straightforward ducts, pumps, valves, and sand. The novel system exhibits potential for tackling world issues in a affected person, considerate, and human-scaled means.
A Small Country with Large Heating Needs
Big issues demand huge options, and there may be maybe no greater Twenty first-century downside than local weather change. To meet this problem, many governments and organizations are investing in new expertise to assist reduce the usage of fossil fuels. These initiatives have largely targeted on renewable electrical energy technology, distribution, and storage.
“When you ask people about cleaner energy, they think of electricity,” says Tommi Eronen, CEO of Polar Night Energy. “But we also have to cut emissions from heating.” Out of Finland’s energy-related emissions, 82 % come from heating home buildings (Ref. 1). “We want to replace all of that if we are to have any hope of meeting our global climate goals,” Eronen says.
Think Globally, Heat Locally
The spirit of “Think Globally, Act Locally”, a mantra related to the Nineteen Sixties, lives on with Polar Night Energy’s crew of innovators. Their journey started with a query posed by its founders, Tommi Eronen and Markku Ylönen, once they have been college classmates: “Is it possible to build an energy-self-sufficient and cost-effective hippie commune for engineers using only solar power?” After commencement, the undertaking they codenamed “Hippie Commune” grew to become Polar Night Energy, with Eronen as CEO and Ylönen as CTO.
What started as a lighthearted (however critical) scholar undertaking led to a 3 MWh/100 kW pilot plant within the Finnish metropolis of Tampere, which started operation through the winter of 2020–2021. The system makes use of electrical energy to warmth air, which is then circulated by an exchanger that heats water and distributes it to a number of buildings within the metropolis’s Hiedanranta district (Figure 2).
Inside the system, electrically powered resistive heating parts warmth air to greater than 600°C. The scorching air is circulated by a community of pipes inside a sand-filled warmth storage vessel. The scorching air then flows again out of the vessel right into a warmth exchanger, the place it heats water that’s then circulated by constructing heating methods. The sand’s warmth storage capability ensures that even when the resistive parts are cool, the circulating air remains to be scorching sufficient to maintain the water (and buildings) heat.
“We only have pipes, valves, a fan, and an electric heating element. There is nothing special here!” Eronen says, laughing.
A Battery for Heat Made from Sand
Noted chemical engineer Donald Sadoway is quoted as saying: “If you want to make a dirt-cheap battery, you have to make it out of dirt.” Polar Night Energy’s system faces the identical core challenges as some other vitality infrastructure. It should ship energy to individuals once they want it, the place they want it, and at a manageable worth. This implies that storing and distributing vitality is as essential as its technology. Existing infrastructure meets these challenges in acquainted methods. For combustion-based heating, fuels like oil and fuel are saved and moved to the place they are often burned. The electrical grid additionally helps the environment friendly distribution of energy and makes use of vitality generated by renewable means like wind and photo voltaic. The intermittent nature of daylight and robust winds, nonetheless, is a cussed downside. Energy storage is required to keep up regular energy output all through the peaks and valleys of renewable inputs. But even with latest advances in battery expertise, storing electrical energy stays comparatively costly, particularly on the scale required for heating buildings. What if, reasonably than storing electrical energy, a “battery” may retailer warmth as an alternative?
Figure 3. Markku Ylönen with a consultant pattern of Polar Night Energy’s dirt-cheap warmth storage medium.
Many standard heating methods already retailer and distribute warmth by retaining and circulating heat water. Eronen and Ylönen acknowledged the advantages of water-based warmth storage in addition to its limitations. “There is only so much heat you can add to water before it becomes steam,” says Eronen. “Steam can efficiently distribute heat, but it is not really cost-effective for large-scale storage.” To keep away from the drawbacks of storing warmth in water, they as an alternative turned to sand — 42 metric tons of it! (Figure 3) After the Sun goes down, the sand’s saved warmth is steadily launched again into the circulating airflow. This retains the air scorching sufficient to keep up regular temperatures within the water that flows by prospects’ radiators. In this manner, sand permits solar energy to maintain individuals heat, even through the darkest and coldest Finnish nights. “Sand provides four times the energy storage capacity of water,” Eronen says. “Sand is efficient, nontoxic, portable, and cheap!”
“We need predictive modeling to answer as many questions as possible, before we commit to assembling all this equipment—and all this sand!”
—Tommi Eronen, CEO of Polar Night Energy
The Sophisticated Analysis Behind a Simple Solution
Cost effectivity is the muse of Polar Night Energy’s worth proposition. “As soon as we decided to pursue this idea, we were trying to figure out how the finances looked,” says Eronen. In their quest to do extra with much less, Polar Night Energy has lengthy trusted numerical simulation instruments. Eronen and Ylönen started utilizing the COMSOL Multiphysics software program as college students and it stays integral to their design course of. For instance, Eronen mentions the specs of an expanded warmth storage system that may serve extra buildings in Tampere. The crew calculated that supplying warmth to a district of 35,000 individuals would require a sand-filled storage cylinder that’s 25 meters tall and 40 meters in diameter. How did they arrive at these dimensions? “The rough quantity of material needed is actually easy to calculate, because we know how much heat we can store in a cubic meter of sand,” Eronen explains. “We also had to determine the space required for efficient heat transfer between the sand and our air circulating system (Figure 4). That is much more difficult to do! We used COMSOL to model and evaluate different design options.”
Figure 4. Tommi Eronen (foreground) and Ylönen inspecting the ductwork of a Polar Night Energy warmth storage vessel.
Multiphysics simulation software program helped form Polar Night Energy’s warmth exchanger design (Figures 5–6). Eronen says, “We built a particular model to explore a design idea: What if we created a super hot core of sand surrounded by heating ducts around the perimeter?” By modeling fluid circulate and warmth switch results within the COMSOL Multiphysics software program, the Polar Night Energy crew may quantify its design’s comparative benefits and downsides. “The simulation confirmed that the ‘hot core’ design was good at storing heat for very long periods of time,” says Eronen. “But for our intended operational cycle, it makes more sense to evenly distribute hot air ducts throughout the sand storage vessel,” he explains.
The sheer scale of Polar Night Energy’s sand-based warmth storage system makes simulation software program indispensable. “We cannot possibly build full-size prototypes to test all of our ideas. We need predictive modeling to answer as many questions as possible, before we commit to assembling all this equipment — and all this sand!” Eronen says. “It is essential for us to use these immensely powerful tools.”
Adapting New Ideas to Existing Infrastructure
By separating the duty of warmth storage from warmth technology and distribution, Polar Night Energy has made its system extra environment friendly and adaptable. There is nice potential for retrofitting their sand-filled warmth storage and switch methods into current infrastructure (Figure 7). Tampere, an inland Finnish industrial metropolis of almost 250,000 individuals, is a perfect testing floor for this new expertise. “Tampere, like many European cities, already has a district heating system that circulates water across entire neighborhoods,” says Eronen. “That enables us to switch many buildings to a renewable heat source quickly,” he says. Polar Night Energy’s pilot plant in Tampere also can faucet into energy from the present electrical grid, together with electrical energy generated by new photo voltaic panels. Reliable thermal storage permits town to generate or buy energy when it’s most inexpensive after which distribute warmth when it’s wanted most.
Figure 7. Part of the warmth switch system put in by Polar Night Energy in Tampere, Finland. The vertical pipes at left are a part of the warmth exchanger, whereas the resistive heater parts are wrapped in white insulation at proper. Between these parts is the air-circulating radial blower.
Today: Finland; Tomorrow: The World
Since the Tampere system started operation through the winter of 2020–2021, the Polar Night Energy crew has been gathering knowledge to match to their fashions. “Our simulations have proven to be very accurate, which is encouraging,” Eronen says. And because the Polar Night Energy crew continues to develop their concepts domestically, they’re aiming to behave globally as effectively. The similar expertise that warms Finland’s lengthy, chilly nights also can present higher vitality administration choices to the remainder of the world. Affordable thermal storage may assist industries and cities seize warmth that’s at present wasted, in addition to steadiness the inconsistencies in wind and solar energy output. But whereas Polar Night Energy is raring to work straight with potential prospects, they notice that the challenges forward are too huge for them to sort out alone.
Tommi Eronen, CEO of Polar Night Energy.
“We want to license this technology. If you operate a power plant, please contact us,” Eronen says with fun. On a extra critical be aware, he provides, “We have to get away from all kinds of combustion, even biomass. We need to protect and restore forests so they can keep removing carbon from the air. Because climate change is happening so fast, we want our ideas to spread as quickly as possible.”
Reference
Statistics Finland, “Over one-half of Finland’s electricity was produced with renewable energy sources in 2020”, November 2021.