I’m working in Heerlen the Netherlands, for Mijnwater BV, a company that is building a new type of district heating grid. It makes use of the disused coal mines under the town, partly as geothermal source of heating en cooling, and partly for storage of heat and cold (because the geothermal source has limited capacity).
This is a new type of thermal grid that is set up so it can simultaneously deliver heat and cold to customers. If a customer needs heating, it returns cooling. If a customer needs cooling, it returns heat. This way, energy is exchanged between e.g. a shopping centre that needs cooling, and homes nearby that need heating.
The reservoir of mine water is used to balance the system, e.g. by storing heat in the summer, and by getting it back out of the mine in the winter. The geothermal source is enough to correct for the limited longer term imbalances.
Heat pumps at the side of the customer are used to drive the system, run electrically. But 1 kWh of electricity can currently deliver 5.5 kWh of heating or cooling power out of the system. When the system grows, we hope that this efficiency factor will grow further.
Now my question: the system is hardwired to exchange heating and cooling power. Some people have described this system as one with ‘prosumers’, and it has been suggested that we should set up some kind of market to buy or sell heat or cooling power with the customers. My feeling is that the exchange is hardwired, so there is no real choice involved, and selling or buying seems unnatural. So I am wondering if this should be organised as a ‘commons’, without any selling and buying.
… but how would one organise such a commons? And would customers for heating and cooling even be interested in thinking about it in that way?
Another alternative (what we’re doing now) is that the company owns the grid, operates as a monopoly utility, that facilitates the heating and cooling in the way that best optimised the system as a whole, while keeping everybody happy. Customers pay a fixed rate for that safety and comfort, and another part that is proportional to the energy use. Because it is driven with electrical heat pumps, and we have huge storage of thermal energy, we can also manage our electricity use in a way to provide some flexibility to the electricity grid (needed for variable wind/sun).
So: we’ve got an energy system that is regenerative, and is set up to reuse cooling for heating, or store it for later times. The current heating/cooling district is rather efficient (a COP of 5.5), and operates purely on electricity. We are making use of waste heat from shops and a computer centre, and we’re busy with industry … which is more complicated.
This type of heating/cooling district can in the future go to zero CO2 by making use of renewable electricity, and feeding the system with some additional waste heat and renewable heat. In places without a disused coal mine, it is possible to set up other types of thermal storage (tank with water, bore into an aquifer, etc). So this 5th generation district heating & cooling (5GDHC) could be a real revolution. In warm countries, you can imagine that such systems would balance more towards cooling, and replace the usual air conditioning systems, using much less energy.
I’m interested in your suggestions if this should be governed as a commons. And how that could then work. Current thinking in EU projects that we are in, is more towards the market option.