Your choices so far:
1 Process heat (> 1000 °C); 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 | Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| Sunshine | Fuel: Liquid | Process heat (150 - 1000 °C) |
| Water | Fuel: Solid | 1 Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | Local heating (ind. house) |
If the first choice by the process owner is to use solid biomass as the prime resource, there will be a choice of energy carrier:
- Either can the energy be contracted from biomass-fired CHP or tri-generation plants and be delivered in the form of electricity.
- Or may solid biomass be brought to the site, gasified and the gas used for the process needs.
- Or may the solid biomass be used in direct firing – depending on how the final product may be affected.
Liquefaction of solid biomass prior to firing it in a process furnace at high temperature will not be viable from a process economy point of view.
In case the only thing desired by the process is a sufficiently high temperature, such as for the burning of building brick in tunnel furnaces of the production of cement in kilns, then direct firing of the solid biomass would be preferred.
In some cases, such as the melting of glass in pot furnaces, it may be crucial that the hot gas brought in direct contact with the products does not contain too much solid ash particles and in such cases it may be advantageous first to gasify the solid biomass. For process control reasons, such as in a large glass tank with multiple burners, gasification on-site may also be an attractive alternative.
In some cases, such as the heat treatment of some high-alloy steels or the hardening of tools, there may be a need for a protected gas atmosphere or for very local heating, and in such cases electricity would be the preferred choice.