Your choices so far:
1 Process heat/steam (50 - 150 °C); 2 District cooling
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| Biomass (digestible sludge) | 2 District cooling | Comfortable indoor climate |
| Biomass (fermentable sludge) | District heating | Electricity |
| Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | 1 Process heat/steam (50 - 150 °C) |
| Sunshine | Fuel: Liquid | Process heat (150 - 1000 °C) |
| Water | Fuel: Solid | Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | Local heating (ind. house) |
The concept of district cooling is to distribute, through under-ground pipes, cold water to the individual customers. The cold water is then used in a heat exchanger in the building or process, providing a cooling and thus replacing the electricity demanding compressor cooling machines by a plate heat exchanger. As the cold water passes one customer after another is will successively be warmed from its starting temperature (say 5 °C) to a level when it no longer useful for efficient cooling (say 15 °C) and it is then returned to the central cooling unit, cooled to 5 °C and then circulated again.
District cooling is best produced by integrating the production of cold water with the production of hot water and electricity and thus to use the cooling need as a basis for new electricity production. This can all be achieved by the use of absorption heat pumps in a tri-generation plant. Biomass-fired tri-generation is already successfully installed in a number of Swedish cities and can be seen in full, commercial operation.
To be feasible, the district heating plant must not be too small.
For process cooling to be viable it is obvious that the industrial site must be located within reach for the district cooling network.