What if simply restoring a closed mine site isn’t the best option?
May 09, 2022
All it takes is a little creativity and there can be a good balance of restoration, reclamation, and asset transformation.
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A mine is only one chapter. The land had a life before the mine existed and the land can be reused again after the mine ceases operations. To prepare the land for reuse, a mine typically undergoes reclamation to restore the land and mimic its predevelopment state. Due to the extensive footprint of an average mine site, the process of reclaiming a closed operation can be long and expensive. When paired with the fact that the land will never fully return to its original state, it begs the question if there’s a better use for the disturbed ground.
Instead of strictly returning the land to its prior state, what if we looked at other uses for the site? Can we use the land for generating renewable energy?
What does reclamation entail?
It’s different depending on the type of mine and its associated facilities, but all modern mines must be restored to mimic the surrounding environment as best as possible. A simple list of activities mines undergo during reclamation would include the demolition of all surface buildings and infrastructure, regrading to a ‘natural’ topography, placement of growth material (topsoil), and reseeding. There are some exceptions like keeping buildings to house pumps for wells that supply the local area or bridges to maintain access for land users.
An open pit mine isn’t always filled back to a level surface. Instead, the finished reclamation site becomes hills with valleys and indents that are covered with native vegetation. But this process is expensive and can take years of moving dirt and rock around to try to make it look like there wasn’t a mine there.
An example of what reclaimed land looks like in a remote location.
Once reclamation is complete, sites can be used for recreation—hiking, hunting, and fishing—or agriculture, like First Nations harvesting native plants or grazing livestock. If you asked the average person what they thought about restoring the landscape to more of a natural state, they’d likely be in favor of that idea. However, we can expand the scope of post-mining land uses.
All it takes is a little creativity and there can be a good balance of restoration, reclamation, and asset transformation.
Environmental: Mines need hundreds, if not thousands of acres of land. This in turn means large areas of natural landscape are disturbed. Why not preserve the environment by recycling this footprint?
For example, solar fields require a certain landscape—free of tall trees and buildings. Once an open pit mine has reached the end of its mining lifecycle, it’s perfect for a solar farm. The "stadium-seating” topography of the mine is an ideal location for solar panel installation, acting like a 360-degree rooftop. Plus, roads and buildings that were already created can be used as service roads for constructing and maintaining the solar farm. The existing power grid that fed the mine could be converted to send electricity the other way with minor modifications.
By using land that has already been disturbed, you’re potentially saving a pristine place from industrial development.
Upgrading and repurposing existing infrastructure can be cost effective and environmentally friendly.
Economic: Mining operations are expensive to build. A site often takes years to develop and costs millions of dollars. The shaft and hoist systems used for underground mining don’t have a lot of recycling options. Old headframes and hoists are expensive to rebuild and transport to new sites. Instead of putting a lid on the shaft and walking away, there is potential to use the entire hoisting plant as a large gravity battery.
A winning solution
Pairing an open-pit solar farm with an underground shaft gravity battery can provide a robust 24-hour renewable energy system with a minimal ecological impact. Together, the two can provide a viable solution for decreasing our fossil fuel use.
The concept of gravity batteries isn’t new. Excess energy raises a ballast that is released during times of peak demand, turning gravity potential into energy. These batteries, when coupled with a renewable energy system, could store excess solar energy generated during the day to be released at night. Headframes and shaft hoists could be turned into a reliable gravity battery with their only key constraints being the weight of the suspended ballast and the depth of the mine. During the day, excess energy pulls a ballast up the shaft. During the night, gravity slowly pulls the ballast down the shaft. The electric hoist motor uses regenerative braking, like an electric car, becoming a generator that puts power back into the grid.
A shaft elevator hoisting system. Winding equipment like this can be re-fit with the ballast.
Reassessing how we view the mining lifecycle
People have been repurposing closed mine sites for decades. Reusing the land in an economically beneficial way is called asset transformation. Many sites have been reclaimed while providing secondary public benefits very successfully. There are mine sites that were largely reclaimed and then had renewable energy farms installed, utilizing the disturbed ground to preserve the local ecology. All it takes is a little creativity and there can be a good balance of restoration, reclamation, and asset transformation.
The technology and systems already exist. The big idea here is more of a cultural shift in how we view a mine’s life. What if asset transformation was considered the norm? What if all sites were required to provide energy or a social or economic benefit to the community once it stopped producing ore?
There are lots of options for every mine site and no mine closure plan is the same. There are great advantages to planning and thinking about how a mine’s closure impacts the local community long after the ore runs out. Who says that you must stop producing benefits when the mine is shut down? Planning far enough ahead can position the mining industry’s assets after closure into green powerplants for generations to come.