Your choices:
1 Comfortable indoor climate; 2 District heating; 3 Biomass (digestible sludge)
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| 3 Biomass (digestible sludge) | District cooling | 1 Comfortable indoor climate |
| Biomass (fermentable sludge) | 2 District heating | Electricity |
| Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | 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 | ocal heating (ind. house) |
To be feasible, a district heating system must have a minimum size. This means that the digester must not only be large enough to supply at least a very significant portion of the total energy needed in the district heating network, it must also be situated in close conjunction to the city or the municipality. So this is first and foremost an alternative for such cases when the digester is located at the wastewater treatment plant or in case the contracted fuel is biogas. To increase the gas production, collection of organic waste from households and restaurants may well be feasible.