I'm really not an expert in regulation of new electricity, but I think one system that has worked in other jurisdictions is really the book and claim system where you can purchase your electricity because electrons are fungibles in systems across the country. You can purchase that electricity directly from that producer, paying him the right price for the use of a fungible electron on the grid. It's not the direct connect approach.
I think this is probably what is preventing the Calgary transport authority from using that green electricity.