07-06 sand battery

[Image above] The first commercial installation of a sand-based heat storage system by Finnish startup Polar Night Energy. Credit: BBC News, YouTube

Aging infrastructure is an urgent yet often hidden concern until it affects you directly. That was my case a couple weeks ago when storms damaged several transmission lines outside of Columbus, Ohio, leading American Electric Power Ohio to forcefully remove nearly 250,000 customers in Columbus and some adjacent cities from the power grid for days with no warning.

Though AEP Ohio says locations for shut off were dictated by where lines were overloaded, groups were quick to point out that the neighborhoods with older infrastructure typically correlate to low-income and minority communities—meaning, intentionally or not, the forced blackouts affected those less able to rebound from the resulting massive loss of food.

While the Public Utilities Commission of Ohio reviews the situation and AEP Ohio promises better communication in future events, without a massive update to grid infrastructure, Central Ohio residents worry outages will become a common occurrence this summer as storms and high temperatures place strain on the fragile electrical system.

This personal experience is just one example of how unprepared we are to handle increasing demands on our energy infrastructure in response to a changing climate. Adapting to this new normal not only requires updating our existing systems but also designing new ways of storing and transmitting energy that can better withstand extreme environments.

Fortunately, researchers around the world are hard at work advancing novel solutions. And this week, a Finnish startup announced the first commercial-scale launch of their new heat storage system.

Tampere-based Polar Night Energy is the brainchild of engineers Tommi Eronen and Markku Ylönen. Their company grew from the knowledge that relying on power stations during cold Finland winters can be extremely expensive and emission intensive.

Their solution for providing stable and affordable thermal energy is a “sand battery.” In this system, electricity generated from solar and wind power is passed through an array of electric resistive heating elements, heating the air around it. This hot air is circulated through a network of pipes inside an insulated sand-filled steel tank, which warms the sand up to about 500°C (932°F). The air then flows back out of the tank into a heat exchanger, where it heats water that is then circulated through building heating systems.

When the sun sets, the sand’s stored heat is gradually released back into the circulating airflow, keeping the air hot enough to maintain the water at a steady temperature. In this way, sand enables renewable energy to keep people warm, even during the darkest and coldest Finnish nights.

Eronen and Ylönen chose to use sand as the heat storage medium due to its superior heat storage capacity compared to existing water-based heat storage systems. “There is only so much heat you can add to water before it becomes steam. Steam can efficiently distribute heat, but it is not really cost-effective for large-scale storage,” Eronen says in an interview.

In contrast, the sand in their system can hold on to the heat for several months, which is perfect for when the sun does not rise above the horizon in Lapland, Finland’s northernmost region.

Yesterday, BBC reported that Eronen and Ylönen completed the first commercial installation of their sand battery in the town of Kankaanpää. It was installed at the Vatajankoski power plant, which runs the district heating system for the area.

“It’s really simple, but we liked the idea of trying something new, to be the first in the world to do something like this,” says Pekka Passi, managing director of the Vatajankoski power plant, in the BBC article.

Learn more about the new installation in the video below.

Credit: BBC News, YouTube