Your choices so far:
1 Fuel: gaseous; 2 Biomass (digestible sludge)
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| 2 Biomass (digestible sludge) | District cooling | 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) |
The best raw material for the production of gaseous fuel is digestible biomass and the best route to do it is by anaerobic digestion.
Anaerobic digestion can be performed in small scales, single-farm scale, based on agricultural residues mixed with manure and droppings, it can be done in intermediate scale at for example a butchery or a brewery making use of their own residues and it can be done in large scale as an integrated treatment of sewage sludge and organic waste fractions collected from a major city area.
In the small-scale case, the gas is often used locally via combustion in a modified IC-engine to provide the farm itself with heat (from the cooling water) and electricity.
In the larger scales, the gas may either be used internally in the process industry to cover the needs for process heating, for co-generation of process heat and electricity via an IC-engine or the gas may be upgraded to substitute natural gas via injection into the gas distribution grid or to be sold as a car fuel.