Could Cumberland's Coal Mines Have a Second Life?

For nearly 80 years, coal mining shaped Cumberland and much of the Comox Valley. The industry finally came to an end in 1966, when the Tsable River Mine closed.

Today, many of those abandoned underground workings are flooded with water, and researchers are investigating whether they could serve an entirely new purpose: heating and cooling buildings.

The idea is called mine-water geo-exchange, and it's one of the initiatives included in the Village of Cumberland's Community Priorities Survey.

Mayor Vickey Brown has been advocating for the opportunity, working with researchers from the University of Victoria to explore whether Cumberland's mining infrastructure could support future economic development.

It might sound experimental, but Vancouver Island University has been using a similar system in Nanaimo since 2018.

So what exactly is Cumberland exploring, and could it make sense here?

Concept illustration showing how water from Cumberland's flooded coal mines could be used to heat and cool industrial buildings. The project remains in the research stage, and no construction has been approved. Illustration: Cumberland Matters. For illustrative purposes only, not an engineering design.

In places such as Iceland, naturally hot geothermal water is commonly used for district heating, supplying warmth directly to buildings through networks of pipes.

Cumberland's proposal is a little different. It would take advantage of the relatively stable temperatures of water in its abandoned coal mines.

University of Victoria researchers estimate that water in the flooded mines remains between approximately 10°C and 20°C throughout the year.

That's not warm enough to heat a building directly, but it can be a useful starting point for a heat pump.

In winter, heat pumps could extract energy from the mine water and raise it to a temperature suitable for heating buildings. In summer, the process could be reversed, transferring excess heat underground.

The relatively stable underground temperatures could allow heat pumps to operate more efficiently than systems exposed to changing outdoor temperatures.

The technology could serve a single building or support a larger district energy network connecting multiple buildings.

This wouldn't generate electricity or provide free heating. The system would still need electricity to operate its heat pumps and circulation equipment. The potential savings would come from using that electricity more efficiently.

The Bevan Industrial Lands, nearby Comox Valley Waste Management Centre and approximate locations of three historic Cumberland mines. Current geo-exchange research focuses on the No. 4 Mine, while the original proposal examined the No. 6 Mine near downtown. Locations are approximate and do not show the full extent of underground mine workings. (Illustration: Cumberland Matters)

Although mine-water geo-exchange is an established technology, every abandoned mine system presents different engineering challenges.

Water chemistry is one consideration.

Depending on local conditions, mine water can contain dissolved iron, minerals and other substances that may cause corrosion, scaling or deposits inside pumps and heat exchangers. These problems could increase maintenance costs or reduce system efficiency.

That doesn't mean Cumberland's mine water is necessarily contaminated or unsuitable. Its characteristics would need to be established through testing.

Another consideration is protecting surrounding groundwater.

Drilling into abandoned mine workings may involve passing through different underground water-bearing formations, or aquifers. Wells need to be properly constructed, cased and sealed to prevent unintended connections between those groundwater sources.

The design would also need to account for how extracting and returning mine water could affect groundwater levels and movement.

These are engineering and environmental considerations that can be addressed through appropriate design and safeguards. They do, however, need to be understood before deciding whether the resource can be developed safely and economically.

Even if researchers demonstrate that Cumberland's mine water can provide reliable heating and cooling, there's another important question.

Would the additional capital investment be justified by lower operating costs, environmental benefits and potential economic development?

Modern commercial air-source heat pumps are already effective in relatively mild climates such as the Comox Valley.

A business constructing a building at Bevan could install its own heat pumps without requiring underground mine access, centralized pumping facilities or a network of pipes connecting multiple properties.

A mine-water system might consume less electricity, but that advantage needs to be weighed against its additional infrastructure costs.

Those could include drilling wells, installing pumps and heat exchangers, distribution piping, monitoring, maintenance and eventual equipment replacement.

The financial comparison must also account for conventional equipment that a shared system could replace, along with the potential benefits of reduced emissions and attracting businesses.

Greater energy efficiency doesn't automatically mean a lower overall cost.

Interestingly, this isn't the first time Cumberland has explored using local energy resources to attract industrial development. In 2018, the Village proposed working with FortisBC and Comox Strathcona Waste Management to make renewable natural gas from the nearby landfill available to businesses at Bevan. A 2024 agreement between the regional waste service and FortisBC has since advanced that concept, although its final implementation status remains unconfirmed. There may eventually be opportunities to coordinate the two energy initiatives, particularly if waste heat from a gas-processing facility could be recovered. That possibility would require additional engineering and economic assessment.

The original downtown proposal may still deserve consideration if the Village eventually proceeds with a significant redevelopment of its municipal properties.

A larger development combining municipal offices, recreation facilities, commercial space or housing could potentially create concentrated energy demand suitable for a shared system.

VIU's experience illustrates the advantage of connecting substantial buildings with predictable heating and cooling requirements.

New construction could also be designed around geo-exchange from the beginning, avoiding some of the costs associated with retrofitting existing buildings.

The downtown option shouldn't necessarily be ruled out, but it would require its own engineering assessment and business case.

When I first heard about this proposal, I was skeptical. It sounded like an interesting idea on paper, but potentially an expensive one with an uncertain payoff.

After spending some time researching the technology, learning about the working system in Nanaimo and looking at the possibilities for Cumberland, I've come to appreciate why it's worth exploring.

For $10,000 from the Comox Valley Waste Management Host Amenity funds, the Village is supporting research that gets us thinking about our coal-mining history, the future of the Bevan Industrial Lands and different ways of meeting our energy needs.

Even if the research ultimately concludes that a mine-water system isn't economically viable, I think that's money well spent. We're learning more about a resource beneath our community, bringing university and engineering expertise to Cumberland, and encouraging conversations about opportunities we might otherwise overlook.

Mayor Brown deserves credit for pursuing the idea and helping bring that research to Cumberland.

Of course, investigating an opportunity is very different from committing to build it. Before considering a substantial investment, we'd need to understand the construction and operating costs, potential customers, environmental benefits and who would carry the financial risk.

The Community Priorities Survey asks residents about exploring industrial geo-exchange, not approving a construction project. I think that's an important distinction.

I'm supportive of completing the research and making the findings publicly available. Whether a system should eventually be built will depend on the engineering results and a sound business case.

Cumberland's coal mines helped build the Village's first economy. They might have a role in supporting its next one.

And even if they don't, spending $10,000 to find out seems like a reasonable investment in understanding what's possible.