As more and more countries reduce coal-mining activities in line with zero emission targets, more and more mines shut down. For the people who own those mines, however, it’s far from the end of the story.
“Mine owners are left with a series of problems when mines close,” says Henrik Boman, CEO of Sustainable Energy Solutions (SENS). “It tends to happen very rapidly. Owners, mine operators and staff don’t have any kind of pillow to cushion them. The issue is how to create a second life for a disused mine.”
The cost of decommissioning and reclaiming mines means that particularly in poorer countries, where regulations are inadequate, owners often do nothing, putting local society at risk.
In Indonesia, 176 children died after falling into empty mines between 2014 and 2021. Even in wealthier countries, there are still accidents. With some 150,000 abandoned mines in the U.S., nearly 200 people have died since 1999, according to the M.H.S.A..
Abandoned mines also emit methane and can collapse or contaminate groundwater for decades. And even when land is reclaimed, albeit using best environmental practices, it rarely returns to its natural state of wilderness.
Most abandoned mines usually fill up with water and it’s here that Boman’s company comes in. SENS has pioneered a series of technologies using Underground Pumped Hydro Storage (UPHS) technology which enables mine owners to turn the water in these empty mines into a useful storage of energy.
SENS employs its own UPHS technology in a closed mine shaft in which a turbine has been installed. Energy is created by using the difference in height between two reservoirs and a water turbine in the mine shaft. “Whenever you have a higher reservoir with water, there is energy,” Boman explains. “When the water is let out of the higher reservoir, it generates electricity.”
After the water from the mine is partially pumped out from the bottom, another Swedish company, Clearwell, cleans it with a containerised water purification system before it is safely released into the surrounding lakes, rivers or marshland. Some of this water is also stored above ground in a dam which can be released into the shaft where the turbine resides.
Pumped hydro storage has been used across Europe and elsewhere, often with a river as the lower reservoir, lakes or even the ocean. Where SENS’ technology is different, however, is that it runs entirely on renewable energy.
This comes from a nearby solar or wind park which generates green energy to run the pumps using compressed air and giant batteries which store up energy for rainy or cloudy days when solar power is unavailable.
These create enough energy to drive the pumps pushing the released water from over 400 meters down in the mine reservoir to ground level in the dam, where the water is again cleaned continuously in Clearwell’s container. The key thing is that the entire system is self-sufficient when it comes to energy, while excess energy can be sold back to electricity companies to help balance the grid.
SENS recently tested pumped hydro storage at the Lilla Båtskär iron ore mine below the sea at the Finnish island of Åland. “The EU is providing grants to develop the concept, so there is some kind of guarantee of its commercial viability,” notes Boman.
As well as battery and solar projects, the company is also collaborating on pumped projects such as the Rožná uranium mine in the Czech republic, with a pre-feasability study completed at the end of 2023, and Spieonkop in South Africa in a joint venture with Kracht Alpha.
Two years after its listing on NASDAQ Stockholm, SENS is in talks with electricity companies, landowners and local authorities across Sweden as well as further afield in Africa and Australia.
“We’re also providing mine owners with a possibility for an income stream, and opening up the possibility of re-employing mineworkers,” says Boman.
In May this year, SENS announced that that Axpo, Switzerland’s largest producer of renewable energy, would acquire and finance the SENS’ solar plant and battery storage projects in Filipstad in Sweden. Boman says this will make Filipstad one of the largest energy storage plants in Sweden, with UPHS, a solar park and battery systems.
“We have had a bit of a breakthrough with larger companies reaching out to us now,’ observes Boman. “There are several kinds of companies who realise they might not only need battery storage solutions, but also larger stores of energy from mines. We can provide energy on a much larger scale than they could alone to enable them to store energy in the water and produce clean water – and sell energy back to the grid as well.”
Source: Forbes
