By Nermina Harambasic P.Eng CDI.D, founder of O-MOD, and capital project oversight /advisory consultant
Food supply at remote mine sites is one of the significant operational issues. Some of these sites are fly-in, fly-out, which makes food deliveries even more challenging. Even mine sites accessible by year-round roads face significant cost of food deliveries due to their distance from major distribution centers.
To overcome some of these issues and strengthen supply chain resilience, adding food production to mine site facilities would benefit the overall operation.
Food production facilities in some cases might continue to operate after mine closure as part of the operation’s closure plan, where the transition from mining to food production would provide ongoing benefits for local communities.
Mines are, by their nature, a source of low-temperature geothermal energy. Geothermal energy has been utilised for food production and facility heating for a long time. There have even been recent attempts to convert underground mines to subterranean farms for the benefit of local communities.
Rather than placing food production completely underground where artificial grow lighting is required, we are proposing to use a sunken greenhouse design where the benefits of both natural light and geothermal energy are available. Soil is used, both as an insulator and the source of low-heat geothermal energy.
‘Citrus in the snow’ for mine sites
One variation on this concept, where air is used in the geothermal loop, has been successfully implemented since the early 90s.
The first installation, known as ‘Citrus in the Snow’, at a farm in Nebraska, USA, has successfully produced vegetables and citrus fruit in sub-zero temperatures for decades. This design has been replicated at hundreds of locations.
Mine sites with ventilation systems can be adapted to use ventilation streams as a source of geothermal heat for these food production facilities.
Sunken greenhouses can be adapted to open-pit mines as well, taking into consideration the pit configuration and safety constraints. Mines where permafrost is present will likely need additional assessments and design features.
Having this type of food production on site has multiple benefits:
- Lower cost of food supply
- Year-round access to some fresh food
- Food security/independence/resilience
- Green space for additional activities for remote mines/communities
- Improved mood/mental health of workforce
- Some mines limit the number of hours underground for their workforce, work at green houses might be used as leverage
- Improved business cycle, continuous economic benefits after mine closure
- Shared benefits with local communities
- Beneficial environmental impact
Building climate resilience
The cost to create these facilities is relatively low; the materials expense is in the range of tens of thousands of dollars, while the earthworks can be easily undertaken with machinery available at the mine site.
As climate-related uncertainties increase impacting food security, adding this type of food production to mine sites could significantly reduce operational risks while creating many additional social benefits.