Your choices:
1 Biomass (digestible sludge); 2 District heating; 3 Process heat (50 - 150 °C)
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| 1 Biomass (digestible sludge) | District cooling | Comfortable indoor climate |
| Biomass (fermentable sludge) | 2 District heating | Electricity |
| Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | 3 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) |
As mentioned, district heating may be provided in the form of hot water (most common) or steam. These media will set temperature limits so that hot water can usually not be supplied at temperatures exceeding 120 °C and steam is not commonly delivered at temperatures exceeding roughly 250 °C because of the losses inherent in the distribution system.
However, many industrial sectors such as the paper-and-pulp sector, food manufacturing industries, saw-mills, joineries and furniture manufacturers, greenhouses and many other will have a pronounced need for heat supply below the temperatures available with district heating systems.
The advantage for the individual company is that outsourcing the heat production to a specialised energy production company they may concentrate on their primary business idea and trust that the energy needed for the process is there at any instant. At the same time, the advantage for the energy utility is that industrial customers will provide for a stable base load, increasing the total energy turnover and scale of the system and maybe make electricity production feasible.
However: When digestible sludge is the source of energy, logistics will prevent the establishment of large plants. Rather, the plant size will be limited by the local availability of the biomass than from the potential market. So though the district heating network as such may benefit from the demand for process heat, the anaerobic digestion plant will most probably not be the major source for the energy distributed in the district heating system.