Your choices:
1 Fuel: gaseous; 2 Biomass (solid); 3 Electricity
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| Biomass (digestible sludge) | District cooling | Comfortable indoor climate |
| Biomass (fermentable sludge) | District heating | 3 Electricity |
| 2 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) |
In case the final aim with the process is to produce electricity, then thermal gasification immediately followed by combustion of the gas in a steam boiler for CHP or tri-generation will only make the process from fuel to energy carrier more complicated. In this case, the best route is to use direct combustion of the solid biomass in a modern steam boiler, thus reducing the process complexity to a minimum.
To increase the electricity efficiency, the use of a combined cycle (steam turbines and gas turbines integrated in a common process) may become advantageous. To do this, the solid biomass must first be gasified so as to be made suitable for the gas turbine, but the gas will also have to be cleaned prior to the gas turbine combustion chamber. This process – the cleaning of the gas – is the bottleneck for this type of process and until the problems with hot-gas cleaning have been resolved, this is not a feasible process.