Your choices:
1 Biomass (solid); 2 Fuel: gaseous; 3 Process heat
| 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 |
| 1 Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | 2 Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| Sunshine | Fuel: Liquid | 3 Process heat (150 - 1000 °C) |
| Water | Fuel: Solid | 3 Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | Local heating (ind. house) |
As pointed out, thermal gasification is a complicated process and the use of it should be restricted only to such cases when the added value at the end-user is high enough to pay the price in terms of costs and energy lost through the conversion from solid fuel to gaseous. In the case of low-temperature applications where district heat or steam may be used as energy carriers, the added value is usually not enough to pay for the complexity introduced by gasification.
Temperatures ranging from 150 to some 1000 °C are common in many types of industries like asphalt works, metal manufacturing and heat treatment, metal casting, glazing of ceramics end numerous others.
With increasing temperature demands the share of exergy increases but in case fuel-firing is used for the production, then any fuel that is combustible will also be able to deliver any of the temperatures desired in this interval. To put it simple: In case something can burn it will already produce temperatures exceeding 1000-1100 °C. If such temperature is not reached, then the fuel will not burn.
For temperatures exceeding 1000 °C, such as glass melting, steel reheating for rolling, the burning of ceramics like building brick or cement, fossil fuel firing and electricity are today the major sources of energy supply.
As mentioned, the product gas from a thermal gasifier will already have a high temperature (6-800 °C) when it leaves the gasifier and there will be no real problems to use that gas directly in a flame furnace, thus replacing fossil fuel. However, it must be remembered that a significant amount of the ash originally in the solid fuel will still be present in the gas, and so will the water originally held in the solid fuel. This means that the interior atmosphere in the furnace may be altered as (e.g.) oil is replaced by gasified biomass and this may in turn affect the product. Therefore, caution must be taken to avoid a negative impact on the product, while there are basically no thermodynamical constraints to the possibility to replace fossil fuel such as LPG, natural gas or fuel oil in a lot of high-temperature applications.