“The refrigeration system makes one end cold and and one end warm.”
Dave Pearson, Star Refrigeration
This Youtube interview reveals some innovative thinking going into more renewable heating options for Scottish homes.
The air conditioning systems we are familiar with in North America typically pump heat out of the building into the ambient air, so as to cool in the summer. In Scotland, the goal is to heat houses using heat pumps, which operate in the opposite manner, pumping from outside inside. Principle 13 – The Other Way
Star Refrigeration is taking this a step further, extracting heat from river water. Running in this manner, a heat pump can produce four times the heat than if the electricity had been used to produce resistive heating, thanks to the relatively mild temperature of the water, its high density and constant flow.
The water winds up colder as a result and can be deployed to cool data centres and the like. Principle 6 – Universality
For slightly lower efficiency, the heat pump can be made to raise the water temperature to near boiling so that it works in existing home radiators. Principle 35 – Parameter Change
To make the installation economical and consolidate maintenance, these water circuits are built on a large scale, encompassing neighbourhoods rather than single homes. The same circuit of hot water can be used to de-ice bridges. Principle 6 – Universality
In some jurisdictions where these systems are being used, the majority of electricity comes from renewables like wind farms. A useful coincidence: a brisk wind will increase the amount of electricity produced at a time when the same cold wind is increasing the demand for home heating. Principle 22 – Blessing in Disguise
The river water does get cooled in the process, but because of urbanization the rivers have actually been getting water, so this effect is restorative, not polluting.
Something else I hadn’t thought of – if a municipality isn’t close to a river, it is certainly close to a sewage treatment plant, which can also be used as a source of heat.
Water is a great store of heat, so when electricity is inexpensive the heat pump can raise the temperature on the hot side of the loop for use later. Principle 10 – Prior Action and Principle 16 – Partial or Excessive Action