| I happened to get a tour of our geothermal district heating building last week, it was really interesting. The entire neighbourhood of about 2200 houses is heated and cooled by this installation. About 60% comes from the heat pumps that get their water from two well pairs, about 40 and 80 meters deep. It's not a closed system and the ground water flows about 50-100 meters to either pair. The remaining capacity comes from a gas turbine that generates electricity to sell back to the net, and the residual heat is captured and used to heat the district. If the demand isn't there, it's pumped back into the ground for future use. The third method is what amounts to basically a giant electric kettle, which has the worst COP factor, but there are times here in The Netherlands when energy prices are negative, and that's when they shut down the gas turbine and use the electric heater instead. There are three pipes going to every house in the district, one with hot water, about 70 degrees and used for both floor heating and hot water, one with cold water for cooling in the summer, and a return pipe. It removes a lot of infrastructure from your house, the hot water goes directly in your floors, so no boilers or furnaces. There's a small heat exchanger that warms the tapwater for showers, and you have zero maintenance. |