Your choices so far:
1 Fuel: liquid; 2 Biomass (fermentable sludge)
| 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 |
| 2 Biomass (fermentable sludge) | District heating | Electricity |
| Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| Sunshine | 1 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) |
The product from fermentation is a dilute alcohol that needs be concentrated through distillation to attain fuel quality. While fermentation of sugars may yield alcohol (ethanol) concentrations about 15%, at the very least 45% is required to make the ethanol a combustible fuel. And only at even higher concentrations can it be combusted without preheat. To be viable as a commercial fuel, the alcohol concentration should exceed 80% but usually there is no reason to stop the distillation until 95% is reached.
The main hindrances for an increase in the use of ethanol today are:
- The price for ethanol. The price reflects mainly the cost for distillation and is not likely to drop within a foreseeable future.
- The raw material for ethanol. A large fraction of today's ethanol production is based on dedicated crops (maize) grown on fertile land. An increasing worldwide awareness of the scarcity of such land has triggered a reaction to the use of ethanol as a fuel.
Due to the competition about fertile land, ethanol production should only be based on fermentable residuals or at least on non-edible biomass.