As you pointed out, I've been working for a few decades now on groundwater systems in bedrock aquifers, which Canada is very familiar with. Many of our groundwater basins and watersheds are bedrock-relevant, and this has brought us to understand not just how contaminants move through the system, but how heat is transported through the bedrock system. I think what comes to light is the importance of groundwater in many ways or facets, and the multiple uses of groundwater.
In our community here in Guelph, we're actively extracting aggregate and building stone from quarries. That's an example of how we use our aquifers or our subsurface system not just for the water and the conveyance of water or purification of water but also for the materials that we extract from the subsurface.
However, linking to energy or sources of heating and cooling, I think that low-temperature geothermal is possibly capable of providing.... Up to 67% or 70% of our energy needs are for heating and cooling our buildings, so the concept of being able to essentially use the groundwater, which is, more or less, at a constant temperature in the subsurface, to support heating in the winter and cooling in the summer is something that can be managed, perhaps, within a known volume of the subsurface. We would be able to share that groundwater use not just for drinking water but also for offsetting some of our carbon footprint, something that we so desperately want to do. It's a viable technology, and it's being used in many places around the globe.
I guess what we might need to do is invest in infrastructure to know how we can optimize the use of our subsurface system for multiple purposes.