Your choices so far:
1 Fuel: gaseous; 2 Biomass (solid)
| 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 | 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) |
Only very scarcely does the added value gained by transforming solid biomass into gaseous form, still containing the water and part of the ashes, pay. The upgrading of gasifier gas to commercial and tradable fuel quality is a complicated process since the gas composition is complex and since the starting point is a hot gas still containing complex hydrocarbons and inorganic ash components. Once the problem with gas cleaning is solved there will be multiple options for a subsequent processing and upgrading of the gasifier gas for numerous purposes. This is known as the "biorefinery concept" but has so far not been realized on a commercial basis.
For biorefinery processes the gas will have to be of syngas quality. This will call not only for oxygen-and-steam blown gasifiers but also for gas reforming and water-gas shift reactors and they will require that the gas is cleaned. Finally, many synthesis processes will require elevated pressures so the gasifier should best be pressurised. Thus the process will become expensive and it becomes crucial that the added value with the end-product can pay for the costs.
One product group that may become feasible once these problems have been overcome is car fuels such as bio-DME (di-methyl-ether), methanol and others, but so far they are not feasible.
Gasifier gas should therefore, in the first instance, be used on-site and combusted either in an industrial process or in a boiler without first having been cleaned.