Biofuels

BIOFUELS

A liquid biofuel is a fuel produced from non-fossil organic materials originated from biomass.
It is also called agrofuel or vegetal fuel.

There are currently two main sectors: 

• Vegetal oil: In this field we can find straight vegetal oil (SVO), also commonly called pure plant oil (PPO) and Biodiesel. SVO can be used directly as fuel in all diesel engines, subject to minor modifications to preheat fuel or without modification, mixed with ordinary diesel (30% of all vehicles, and to 50% in some cases). Major drawback of the SVO use is deposits formation in engines. This disadvantage can be circumvented by a process, called transesterification, a chemical reaction between SVO and alcohol in presence of a catalyst (sodium or potassium hydroxide), which transforms the molecules responsible deposits into methyl esters (or Biodiesel). This biodiesel contains no sulfur, is not toxic  and is biodegradable.

• Alcohol such as bioethanol made from sugars, starch, cellulose or hydrolysed lignin.
  
  FIRST GENERATION OF BIOFUELS PRODUCTION:           ( click on image to enlarge )
  

  

  First generation biofuels (from IFP source)

   They are mainly of two types:
  

  • Bioethanol: The production process transforms the vegetal raw material sugar into alcohol (ethanol) by fermentation. It is mixed with gasoline either directly or in a different chemical form;
  • Biodiesel: The Vegetal Oil Methyl Ester (VOME) can be used directly in fuel B100 (100%) or admixed with petrodiesel (B20, B5...).

  Drawbacks:
  

  • The first generation of biofuels competes directly with the food chain. They are produced from raw materials that can be used in both human and animal food chain. Today, only this generation is produced on an industrial level.

  
  SECOND GENERATION OF BIOFUELS PRODUCTION:
  

  

  Second generation biofuels (from IFP source)
  

  
  

  
  Technologies are being developed to exploit cellulosic materials such as wood, leaves and stems of plants or those coming from waste.
  These materials are called lignocellulosic biomass because they come from wood waste and carbon-containing materials that are not directly used in food production.
  They are not yet deployed on an industrial scale but prospects for implemented over the medium term are emerging. Their large-scale production is expected in years 2020-2030.
  
  There are two main methods of production:
  

  • Thermochemical (gasification): The biomass is transformed into "syngas" (synthesis gas, mainly hydrogen and carbon monoxide). This requires conditions of very high pressure and temperature (of the order of 1000°C and 4 bars). The syngas is converted into synthetic hydrocarbon by catalysis, a so-called Fischer-Tropsch reaction. (Catalysts most common: Iron, cobalt or ruthenium).
  • Biochemical: This process converts the biomass into sugar by enzymes. This sugar is then converted into ethanol by a fermentation process. The obtained product is called “second generation" ethanol. This technology allows the production of bioethanol, biodiesel, biohydrogen or biogas.

  Benefits:
  

  • No food competition and higher availability compared to the first generation of biofuels

  
  THIRD GENERATION OF BIOFUELS PRODUCTION:
  
  

  

  Third generation biofuels (from IFP source)

  
  Some micro-organisms, such as microalgae, already used in the food, cosmetics and fertilizers are considered as an alternative way to traditional fuels
  The production processes are still at the research stage and pilot projects.
  Some species have the ability to produce compounds with high energetic potential as lipids (source of biodiesel) or starch (source of bioethanol).
  Microalgae can also be involved in the production of two other types of biofuels: hydrogen and biogas.
  
  Benefits:
  

  • Higher availability and no food competition
  • Algae biomass (or algal biomass) is very easy to produce by an excellent photosynthetic efficiency
  • Culture on soil is not needed.

  Drawbacks:
  

  • Still experimental.

  
   For more information, see "Microalgae"
  
  Return to "Biomass" or "Uses of biomass"