Your choices:
1 Fuel: gaseous; 2 Comfortable indoor climate; 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 | 2 Comfortable indoor climate |
| Biomass (fermentable sludge) | District heating | Electricity |
| Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | 1 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 | Local heating (ind. house) |
With individual houses, gas from the gas grid is a suitable alternative for heating and tap-water production and individual AC-units are suitable for cooling, but in densely populated areas these systems should be replaced by tri-generation systems providing district heating and district cooling.
With farm-scale anaerobic digesters the local/individual needs for heating as well as at least part of the electricity demand for cooling are met in a sustainable way.
For large-scale units providing district heating and cooling for a city area the digester will have to be large and gas upgrading will become feasible. In case the gas is then injected into the gas grid and the central production plant is gas-fired, a balance may be calculated to show the extent of biogas used or the production of district heating and cooling. A similar balance can be done in case the central production unit has contracted biogas deliveries.