Your choices:
1 Process heat (150 - 1000 °C); 2 Fuel: gaseous; 3 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 |
| 3 Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | 2 Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| Sunshine | Fuel: Liquid | 1 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) |
Some processes, such as the melting of aluminium scrap for the production of secondary aluminium for casting, will basically be more sensitive to temperature control than the components present in the melting furnace atmosphere.
For solid biomass to be an attractive fuel in such applications, it may be advantageous to first gasify the biomass using – in these cases – a simple, air-blown, fixed-bed gasifier in direct conjunction with the furnace. It will be important that the gasifier is cheap and easy to operate since the main business idea will not be the gasification but this will only be a means to adapt the fuel to the process.
What will become crucial in cases like this will be the gas seals in the gasifier and the pressure control with the open-flame furnace: It must be remembered that gasifier gas is highly toxic and when it leaves the gasifier it will be hot and flammable.
So the risks must be considered but there are no real technical problems with an installation like this.
The solid biomass should mainly be selected among low-chlorine and low-sulphur biomasses, so woody biomass in the form of chips, briquettes or pellets would be preferred.
However: If the first choice is to operate the process on gaseous fuel, then the second choice to use solid biomass as the resource will add complexity and expenses to the process and the added value as compared to using biogas should be carefully analysed.