As more countries reduce coal production to meet zero emissions targets, more and more mines are closing. For the owners of these mines, however, this is far from the end of the story.
Sustainable Energy Solutions (SENS) CEO Henrik Boman says: “Miners face a number of challenges when mines close. "It's still early. Owners, mine operators and workers have no cushion. The question is how to give a second life to an abandoned mine."
The costs of decommissioning and rehabilitating mines mean that owners often do nothing, putting local communities at risk, especially in poor countries where regulations are lax.
From 2014-2021, 176 children died in Indonesia's open-pit mines. Accidents also happen in richer countries. According to the MHSA, about 200 people have died since 1999, when there were about 150,000 abandoned mines in the United States.
Abandoned mines also release methane and can degrade or contaminate groundwater over decades. Even when land is restored, it rarely returns to its desert state, despite best environmental practices.
Many abandoned mines tend to overflow, which is where Boman's company comes into play. SENS has developed several technologies using Underground Pumped Storage (UPHS) technology, which allows mine owners to convert water from these empty mines into useful energy storage.
SENS uses a unique UPHS technology where the turbine is on a closed shaft. The energy is generated by the height difference between the two reservoirs and the mine's water turbine. "When you have a higher reservoir, there's energy," Boman explained. "When water is released from the upper reservoir, electricity is generated."
After some of the mine water is pumped from the ground, another Swedish company, Clearwell, treats the water with a system of treatment tanks before it is safely discharged into nearby lakes, rivers or wetlands. Part of this water is stored in an above-ground dam and can flow into a shaft where the turbine is located.
Pumped hydraulic accumulators are used throughout Europe and beyond, often from rivers to underwater reservoirs, lakes and even the sea. However, the difference of SENS technology is that it is completely based on renewable energy sources.
It comes from a nearby solar or wind farm that produces compressed air and green electricity to run the pumps, using giant batteries that store energy on rainy or cloudy days when solar power is unavailable.
This generates enough electricity to power pumps that pump waste water from more than 400 meters deep in the mine reservoir to the dam ground, where water from the Clearwell tank is continuously recycled. Crucially, the entire system is energy self-sufficient, and can sell excess electricity to suppliers to help balance the grid.
SENS recently tested pumped storage pumps at the Lilla Båtskär subsea iron mine in Finland. "The EU provides financial support for the development of the concept, so there is a guarantee of its commercial viability," says Boman.
In addition to batteries and solar panels, the company is also involved in pumping projects, such as the Rozna uranium mine in the Czech Republic, which will complete a feasibility study by the end of 2023, and Spieonkop in South Africa through a joint venture. . Kracht Alpha
Two years after listing on NASDAQ in Stockholm, SENS is talking to utilities, landowners and local governments in Sweden, Africa and Australia.
"We also provide opportunities for mine owners to generate income and re-employ miners," Boman said.
In May this year, SENS announced that Axpo, Switzerland's largest renewable energy producer, would acquire and finance SENS' solar and battery projects in Filipstad, Sweden. According to Boman, Filipstad will become one of Sweden's largest energy storage facilities with UPHS, solar park and battery systems.
"We had a small breakthrough, and now bigger companies are coming to us," says Boman. “There are different types of companies that need not only battery storage solutions, but also larger mine energy storage. We can provide energy on a much larger scale than they do, which allows us to store energy in water, produce clean water and sell energy back into the grid.'
