Many energy and power innovators around the world plan to harvest more power from abandoned coal mines, but not by digging up dirty deposits.
Instead, this concept utilizes gravity and renewable energy to transform the defunct locations into next-generation power sites, according to reports from "Reasons to be Cheerful" and "Popular Mechanics".
The method is fairly simple. Excess renewable energy powers winches that lift weights, which, in this case, are located in old mine shafts.
The suspended bulk represents stored energy, crucial to utilizing sun or wind power at night and when the breeze is slow. It's a process similar to so-called water batteries, where renewable-powered pumps send water to a reservoir as stored power. In both cases, the weight or water is dropped or released into a lower reservoir, generating electricity, according to the reports and a description from the World Economic Forum.
"This approach not only gives these disused mines a second life, but also offers economic and environmental benefits to communities once reliant on coal," RTBC wrote.
As the world transitions to cleaner energy sources — now accounting for 29 percent of generation worldwide, per the United Nations — storage is becoming a bigger hurdle.
Lithium-ion batteries like Tesla's Megapacks or a giant sodium-ion unit storing energy in China are among other options. But those units require expensive and hard-to-gather materials to build or, at this stage of development, come with other logistical challenges."
Sustainability by Numbers" estimated that tens of millions of tons of deposits will need to be harvested to sustain the energy transformation by 2040, much of it for batteries. But that's far short of the 16.5 billion tons of heat-trapping dirty fuels pulled from Earth annually, per the report.
Gravity batteries could be a cleaner bridge from our dirtier energy past to a sustainable future, key to avoiding worst-case scenarios triggered by our warming world. Increased risks for severe weather and wildfires are among the changes already being felt, per NASA.
In the U.S., there are 550,000 abandoned mines, representing lost jobs and causing environmental hazards, according to RTBC and other reports. The abandoned shafts and more idle industrial sites can become clean-energy hubs, with solar installation potential sufficient to power 200 million U.S homes annually, per the story.