Abandoned Coal Mines Across China Could Become Underground Farming Labs

More than 12,000 coal mines have been abandoned across China, leaving behind enormous volumes of underground space and extensive infrastructure that may be suitable for a new purpose. Researchers believe these former mines could be converted into controlled farming laboratories.

The proposal comes from a team at the Shanxi Province Coal-based Resources Green and High-efficiency Development Engineering Center. Their concept is to use the mines’ networks of tunnels and caverns for "agricultural experiments".

Turning abandoned coal mines into agricultural laboratories

The drawbacks are immediately apparent: underground sites receive no natural sunlight or rainfall, both of which are normally essential to agriculture.

Yet, as the team explains in a paper published in China Mining Magazine, these conditions also bring potential advantages. Underground environments can be tightly managed and shielded from changing weather, the effects of ongoing climate change, and natural disasters.

"Against the backdrop of intensifying global climate change and growing agricultural demand in extreme and enclosed environments, exploring experimental agricultural models in coal mine underground spaces carries important scientific significance and engineering value," write the researchers in their published paper.

That does not mean the conversion would be straightforward, nor does it suggest that every one of the 12,000 mines could become an agricultural research site.

Assessing mine safety and environmental controls

The researchers performed an initial evaluation of structural safety, the practicality of transforming disused mines into agricultural units, and the ability to control light, heat, water, air, and carbon dioxide within them.

Ventilation and drainage were also included in their assessment.

Their findings indicate that at least some mines could offer conditions stable enough to trial alternative farming techniques, which could become more valuable as the climate changes.

"The results show that coal mine underground spaces possess the engineering foundation for constructing agricultural experimental units when the surrounding rock stability meets engineering specifications, and ventilation, drainage, and safety monitoring systems are complete," write the researchers.

"Through artificial light sources and environmental control systems, underground spaces can realize the independent supply and precise regulation of key production factors such as light, heat, water, air, and carbon, thereby supporting the implementation of highly controllable agricultural experiments."

Underground farming could also benefit from geothermal energy. The researchers propose that this resource could provide a sustainable source of warmth for crops while producing substantially lower greenhouse gas emissions.

In addition, groundwater that seeps back into the mines and becomes contaminated with sulfates, metals, and other particles could be treated below ground and then reused for irrigation.

Agricultural experiments rather than conventional crop fields

The researchers are not proposing vast underground fields of crops. Instead, the sites would support research projects examining ways to grow food under a range of different conditions.

"The introduction of agricultural systems into the underground space of coal mines aims not to achieve traditional agricultural production, but rather to construct an agricultural scientific experimental platform for extreme and enclosed environments," write the researchers (via Google Translate).

The South China Morning Post reports that the number of closed mines could reach about 15,000 by the end of the decade. This would leave roughly 7.2 billion cubic meters (254 billion cubic feet) of space unused.

Many difficulties still need to be addressed, and the team has not yet carried out field testing. Nevertheless, the feasibility assessment cites the Callio project in Finland, a successful mine-conversion scheme, as an illustration of what can be achieved.

In time, insights from underground farming could help shape methods for growing crops in harsh settings, including space and remote parts of the world where conventional agricultural systems are unsuitable.

"Overall, coal mine underground spaces can serve as an important carrier for highly controllable agricultural experiments, providing a new approach for agricultural mechanism research in extreme environments and the reuse of underground space resources," write the researchers.

The research has been published in China Mining Magazine.