China Proposes Turning Abandoned Coal Mines Into Underground Farming Laboratories

China has more than 12,000 abandoned coal mines, offering vast underground tunnel and cavern space that a team of Chinese researchers now wants to repurpose as experimental farming laboratories. The proposal, from a team at the Shanxi Province Coal-based Resources Green and High-efficiency Development Engineering Center, is described in a paper published in China Mining Magazine.

Underground sites obviously lack sunlight and rainfall, normally essential for farming, but the researchers argue that subterranean environments can be carefully controlled and are protected from weather fluctuations, climate change and natural disasters. "Exploring experimental agricultural models in coal mine underground spaces carries important scientific significance and engineering value," they wrote, citing intensifying climate change and growing agricultural demand in extreme, enclosed environments.

The team assessed mine suitability using criteria including structural safety, the feasibility of converting tunnels into agricultural units, and the practicality of managing light, heat, water, air and carbon dioxide, along with ventilation and drainage. They concluded that at least some mines could provide environments stable enough for testing new farming approaches, given adequate rock stability and complete ventilation, drainage and safety-monitoring systems. Artificial light sources and environmental control systems, they said, could allow underground spaces to precisely regulate light, heat, water, air and carbon for highly controllable agricultural experiments.

The researchers pointed to added benefits: geothermal energy in the mines could serve as a sustainable, lower-emission heat source for crops, and contaminated groundwater that seeps into mines could be treated underground and reused for irrigation. The idea is not to grow full fields of crops, they said, but to build "an agricultural scientific experimental platform for extreme and enclosed environments," rather than traditional agricultural production.

China's closed mines are expected to number around 15,000 by the end of the decade, representing roughly 7.2 billion cubic metres of unused space, according to the South China Morning Post. No field testing has been done yet, and the researchers cite Finland's Callio project, a mine conversion effort, as an example of what is possible. They say lessons from underground farming could eventually inform how crops are grown in other extreme environments, including in space.