Your choices so far:
1 Biomass (fermentable sludge); 2 Transport
| 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 |
| 1 Biomass (fermentable sludge) | District heating | Electricity |
| 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 | Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | 2 Transport |
| Residual oils/fats etc | Local heating (ind. house) |
Today, this is the main route to make use of fermentable biomass within the energy sector.
For a fuel to be suitable in internal combustion engines (IC-engines) it must meet a number of criteria. For practical reasons (not having to fill the car too often) it will have to have reasonable energy content per volume unit. To maintain the angular momentum of the engine it must not burn too fast nor too slow. Not to cause engine knock it must have a minimum octane value (for spark-ignited Otto engines, i.e. gasoline engines). For the use in diesel engines, the cetane number must not be too low etc.
Ethanol mixes readily with gasoline and mix-in ratios of 5-10% are already used as standard in many countries. Such a low in-mix will not influence the engine performance but once the amount of ethanol exceeds some 40% the engine will need optimisation to perform at its best.
Because of the relatively low energy content per volume (21.2 MJ/l) as compared to gasoline (33.0 MJ/l) any in-mix to higher ratios, such as E85 with 85% ethanol in gasoline, will significantly increase the total volume of fuel that has to be filled. The octane number is hardly affected by in-mix of ethanol since the pure ethanol in itself has an octane number about the same as common, commercial gasoline.
The lowered volumetric heat content of the fuel is, however, not a major problem since it is only a question about the number of filling stations. The main hindrances for the use of ethanol as a gasoline in-mix are instead:
- 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.