Researchers in Finland may have found a way to ensure that sustainably-generated green energy can be made available year-round – and it’s a solution that involves sand.
Polar Night Energy, a team of Finnish engineers in the town of Kankaanpää, recently completed the first-ever commercial installation of a sand battery that promises to store energy generated from either solar or wind-powered facilities for months.
Currently installed in the Vatajankoski Power Plant, the battery uses a resistive heating process similar to the one used for electric fireplaces. Here, energy cheaply generated from either solar or wind sources warms the sand up to 500 C. This generates hot air and circulates through the sand using a heat exchanger.
As a material, sand has long been known to be effective when it comes to storing heat and, over time, heat loss is quite minimal. For this reason, the developers claim that the device can keep sand at a constant 500 C for several months.
Whenever energy prices go up, the battery is made to discharge hot air to warm water for the local district-wide heating system. The water is then pumped to homes, businesses, and community centers.
So when energy prices are higher, the battery discharges the hot air that warms water for the district heating system, which is pumped around homes, offices, and even the local swimming pool.
What Happens Next?
However, while the idea has been proven effective as a heat-generating solution on a village-sized scale, critics wonder if the creators can scale it up for more widespread use and if it could be adapted to generate electricity.
According to the system’s developers, the efficiency decreases whenever the sand is used to simply return power to the local electrical grid. Still, they are optimistic about making significant breakthroughs.
Likewise, some experts see the new technology as a potential opportunity for the industrial sector to finally reduce its dependence on fossil fuels.
Cost is a Concern
Another key point critics point to is that sand batteries could prove expensive in the colder months.
This was a point made by Elina Seppänen, an energy and climate specialist for the city of Tampere, where Polar Night Energy first tried its idea out.
Seppänen opines that if sand batteries are installed at a few power stations but used only for a couple of hours or son during the coldest winter months, these could be a bit too expensive to maintain.
But she added that if flexibility comes into the equation regarding usage and storage of heat, it will help drive down operational costs.