I don't know if it's just depth issues, I think I saw a story about some sample projects in Alberta where they were looking for the right types of rock for the

I don't know if it's just depth issues, I think I saw a story about some sample projects in Alberta where they were looking for the right types of rock for the heat exchange to occur. It definitely sounded significantly more complex than just drilling holes, but finding areas with the correct properties to get worthwhile ROI. One nice advantage is it draws on skills common to the oil and gas industries.