Abandoned coal mines are often held up as symbols of the changing state of climate or the economy. But academics at the University of Nottingham see in them the potential future of food. They’ve patented a new system revolving around what they call “deep farming”—turning old coal mines into fully functioning farms.
Deep farms would have advantages that current land-based farms lack, including a controlled climate uninfluenced by weather and no need for expensive farming equipment. They wouldn’t need to be built in coal mines, but the scientists see them as a perfect starting point.
“Tunnels and shafts would need less energy with heating, so are very attractive for food production. They’re almost perfect,” says Saffa Riffat of Nottingham, speaking to the BBC. “You’re looking at about £30,000 [~$38,240] to set up one shaft and the running costs are very low—less than the energy consumed by three houses each year. With natural sunlight, the costs are even less.”
In a press statement, Riffat estimates that “a small Deep Farm can produce 80 tonnes of food per annum,” or around 176,370 pounds of food per year. These farms would allow for year-round food production and “up to 10 crop cycles per year could be achieved compared to 1-2 cycles for conventional agriculture…1 indoor acre is equivalent to 4-6 outdoor acres or more, depending on the crop.”
Potential crops include lettuces and leafy greens like spinach and kale, herbs like basil and mint, strawberries, mushrooms, carrots, eggplants, and a wide variety of others.
Deep farming would incorporate many existing technologies—hydroponic planters with nutrient-rich water, aeroponic plants growing with a mist, and LED units to create photosynthesis. And if they can use groundwater and be located close to the communities they serve, deep farms could reduce the CO2 emissions of farming and cut down on transportation costs at the same time.
The British researchers see the UK, with over 150,000 abandoned coal mine shafts, as a perfect place to start.
“We have a major issue with food production and supply with the world’s population expected to reach nine billion by 2050,” Riffat says. “We need to do this for our future. We have a growing demand for food, especially in the cities, but less space to grow it.”