Liquid biofuels for Bio-Turbines

Today liquid biofuels can be used for heating (substituting conventional fuels), for cogeneration (simultaneous production of electric energy and heating) or for mobility (transport).

As far as concerns the commercial technologies available today for the conversion of biomass resources into solid, liquid or gaseous biofuels and for the production of heat, power or for transport, these can be subdivided into two main categories:

•    Small scale technologies for decentralised bioenergy production (activity relevant for rural development);
•    Medium to large scale technologies and schemes for centralised bioenergy production (industrial activity).

Liquid biofuels, as said before, are produced from biomass. Biomass denotes plant materials that are part of the short carbon cycle. This means that the CO₂ that these crops take up from the air during their life for their growth by means of photosynthesis returns to the atmosphere when they are converted into energy. In order to be able to speak of a “renewable” energy source, the stock of biomass must at least be kept constant. Because no net CO₂ emissions are released to the air (apart from the emissions due to production and transport of the biomass and biofuels) biofuels can be considered “climate-neutral”.

There are two kinds of conversion process: biochemical and thermochemical. In the first process, involving anaerobic digestion or alcohol fermentation, fuel is obtained by means of chemical reactions caused by the presence of enzymes, fungus and microorganisms.

With the second process, involving carbonisation, gasification or pyrolysis technology, either solid, gaseous or liquid biofuels are obtained by the action of heating and of a catalyst.

Among the promising alternative liquid biofuels, the most interesting are indicated here below and analysed in this report:

• Vegetable oil
• Biodiesel
• Bioethanol
• Biomethanol
• Dimethylether
• Fischer-Tropsch diesel
• Pyrolysis oil
• HTU oil