Your choices so far:
1 Fuel: liquid; 2 Residual oil/fats
| 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 |
| 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 |
| 2 Residual oils/fats etc | Local heating (ind. house) |
Today, there are commercial, bio-based diesel substitutes available on the commercial market, one of the more well-known being RME or Rape-Methyl-Ester though the more general name is FAME or Fatty Acid Methyl Esters. The popular name is biodiesel.
These fuels are produced using a low-temperature chemical conversion based on fatty acids. The raw material can be excess vegetable oil from agricultural production, rapeseed oil, soybean oil and alike but also residual cooking oils from – for example – restaurants or from food processing.
The advantages with the upgrading process are mainly three:
- First it serves to homogenise the properties of the fuel so that the very inhomogeneous feedstock becomes a standardised fuel within narrow quality limits.
- Second it serves to make the fuel storable. The raw oil qualities will slowly oxidise and solidify unless contaminants and unsaturated fatty acids are removed or neutralised and this is achieved by the upgrading.
- Third the fuel produced attains sufficient quality for the immediate use in the transport sector.
Not only is transesterification one of the few routes that can yield a diesel oil substitute from waste fractions but the transport sector is also one where the willingness to pay is the highest, so this is a sector where the upgrading process may be paid for by the added value.
The final fuel quality, as measured by the cetane number, is strongly depending on the combination of feedstock and alcohol but some combinations – like coconut oil and ethanol – will typically yield cetane numbers > 70. Such quality fuel, provided it is not contaminated, can serve as a diesel substitute without any need for modifications of the engine while other fuels, such as RME produced from rapeseed oil and methanol (cetane number ≈ 50) may call for engine modifications.
As a fossil oil replacement fuel in process industry, however, the cetane number is of no importance and these fuel qualities may readily replace light fuel oil in basically any application.