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ADVANCED BIOFUELS


A wide range of terms and approaches are used to refer to advanced biofuels. These different approaches arise partly because a great diversity of biofuels feedstocks and processes are currently being developed.

The EIBI (European Industrial Bioenergy Initiative) provides a good definition that fixes three main characteristics. Advanced Biofuels are those: (1) produced from lignocellulosic feedstocks (agricultural and forestry residues and wood-based biomass), non-food crops (grasses, miscanthus, algae,…), or industrial waste and residue streams, (2) having low CO2 emission or high GHG reduction, and (3) reaching zero or low ILUC (Indirect Land Use Change) impact. Many advanced biofuels can be blended with fossil fuels in existing vehicles and current infrastructure (“drop-in” fuels) and others need specific engines and new technologies for the transport and the storage.

Producing these advanced biofuels requires high-tech facilities: biorefineries using the last technologies and processes. The feasibility of such plants is one of the key points to release the whole potential of this new generation of biofuels. 

The following contains a general description of some of the main types of advanced biofuels being developed and links to posts with information about commercial biorefineries or pilot plants producing those biofuels. 

1. Cellulosic ethanol
Posts about CELLULOSIC ETHANOL.

Process: Enzymatic hydrolysis and fermentation.
Feedstock: Lignocellulosic agricultural and forestry wastes and purpose-grown non-food crops.
End product: It is the same as conventional bioethanol. It is typically blended with gasoline (10-25% blend with current vehicles and up to 95% blend in specialized engines).
2. Hydrotreated Vegetable Oils (HVO) or Hydroprocessed Esters and Fatty Acids (HEFA)
Posts about HVO.

Process: Hydrotreating.
Feedstock: animal fats and waste oils.
End product: Paraffinic biobased hydrocarbons, free of sulfur and aromatics and with a very high cetane number – renewable diesel used in diesel engines (drop-in biofuel). Jet biofuel, bionaphta and biopropane can be co-produced.
Examples of commercial biorefineries: Rotterdam Biorefinery / Venice Biorefinery.

3. Drop-in biohydrocarbons
Posts about BIOHYDROCARBONS.

3.1 Bio-oil


Process: Fast pyrolysis.

Feedstock: Lignocellulosic agricultural and forestry wastes and purpose-grown non-food crops.
End product: A complex mixture of oxygenated hydrocarbon fragments. For the production of drop-in transportation fuels (diesel, kerosene or gasoline), chemical treatment (upgrading processes) is needed. Finally co-refining in traditional crude oil refineries is possible.

Summary of the status of the pilot and demonstration plants at 2014 
(only in Spanish): BIO-OIL (3ª parte).
Example of demonstration plant: EMPYRO Project – New commercial scale fast pyrolysis plant.

3.2 Biomass to Liquid (BtL)

Process: Gasification followed by Fischer-Tropsch synthesis.

Feedstock: Lignocellulosic agricultural and forestry wastes and purpose-grown non-food crops.
End product: Biobased hydrocarbons – biogasoline, renewable diesel and jet biofuel.

Summary of the status of the pilot and demonstration plants at 2014 (only in Spanish): BIOMASS TO LIQUID (3ª Parte).


3.3 Alcohol-To-Fuel

Process: Alcohol dehydration, oligomerization and hydrogenation.
Feedstock: Bioalcohols.
End product: Biobased hydrocarbons – biogasoline and jet biofuel.

4. Cellulosic butanol

Process: Enzymatic hydrolysis and fermentation.
Feedstock: Lignocellulosic agricultural and forestry wastes or purpose-grown non-food crops.
End product:  It is an alcohol that can be used as a transport fuel. The molecule has an energy content similar to that of gasoline, it can be burned without modifications in an existing gasoline engine and it is said to be less corrosive than ethanol. Up to 85% blend with gasoline and up to 25% with diesel.

Commercial biorefineries and pilot plants through the world: Biobutanol biorefineries.
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