A biofuel is a liquid or gaseous fuel created from the processing of non-fossil organic materials derived from biomass, eg vegetable materials produced by agriculture (beet, wheat, maize, rapeseed, sunflower, potato, etc.). .).
Although the English language has only one biofuel name, several names coexist in the French language: biofuel (term chosen by the European Parliament), agrofuel or vegetable fuel.
Biofuels are assimilated to a renewable energy source. Their combustion produces only CO2 and water vapor and little or no nitrogen and sulfur oxides (NOx, SOx).
There are three generations of biofuels:
They are mainly two types:
Bioethanol: it is produced from sugar cane, cereals and sugar beet. It is used in gasoline engines;
Biodiesel: it is derived from different sources of fatty acids, including soybean, rapeseed, palm and other vegetable oils. It is used in diesel engines.
First generation biofuels compete directly with the food chain. They are produced from raw materials that can be used in an animal or human food chain. Today, only this generation is produced on an industrial scale.
Second Generation Biofuels
Technologies are being developed to exploit cellulosic materials such as wood, leaves and stems of plants, or waste.
These materials are referred to as lignocellulosic biomass because they come from woody or carbon-based components that are not directly used in food production. These characteristics have a higher availability and non-competitive advantage compared to the first generation of biofuels.
This technology allows the production of second-generation bioethanol, biodiesel, bio-hydrogen or biogas.
It is not yet deployed at the industrial stage but prospects for implementation in the medium term are emerging. Their large-scale production is planned for 2020-2030.
Third Generation Biofuels
The processes still under study rely mainly on the use of microorganisms such as microalgae.
These can accumulate fatty acids that allow for per hectare yields that are higher by a factor of 30 than terrestrial oilseeds. From these fatty acids, it is possible to generate biodiesel. Some species of microalgae can contain sugars and thus be fermented in bioethanol. Finally, microalgae can be methanated to produce biogas. Some of them can also produce biohydrogen.
The main production techniques for first generation fuels are as follows:
Bioethanol: the manufacturing process transforms the sugar of the vegetable matter into alcohol (ethanol) by fermentation. It is mixed with gasoline either directly or in a different chemical form;
Biodiesel: it is made from the reaction between a semi-refined vegetable oil, obtained mainly from vegetable oils (rapeseed, sunflower) with an alcohol. The process is called “transesterification”: vegetable oils are cold mixed with an alcohol in the presence of a catalyst (sodium or potassium hydroxide). Biodiesel is mixed only with diesel fuel.
Second generation Biofuel
Third generation biofuels are still only at the research stage and pilot projects. One of the main lines of reflection is based on the fact that some microorganisms can provide hydrogen or lipids (fatty acids) under the effect of light and other chemical substances.
Challenges to energy
Biofuels represent an additional source of fuel and a new agro-industrial activity. They enable the countries that produce them to reduce their energy dependence on fossil fuels. However, the use of first-generation biofuels may lead to increased demand and higher prices for agricultural products. This can create social instability in poor countries. Indeed, it should be noted that in Haiti and other African countries like Senegal have already erupted riots of hunger.
The combustion of fossil fuels contributes to greenhouse gas (GHG) emissions. For biofuels, the carbon emitted during their combustion in the atmosphere was previously fixed by the plants during the photosynthesis. Thus, the carbon balance seems a priori neutral. However, the ideal situation has not yet been reached in practice because the production of these biofuels requires human, agricultural, transport, industrial process work and therefore consumption of fuels and possibly other substances whose use produces Also GHGs.
On the other hand, the sustainability of agrofuel production can be undermined if it is carried out in an unsustainable way: soil depletion, water pollution and the destruction of natural environments for this production.
Evolution of European legislation
The European Directive 2009/28 / EC (1) sets a target for the integration of renewable sources in the transport sector by at least 10% for each Member State by 2020.
The Directive also establishes sustainability criteria for biofuels (in Articles 17 to 19), in keeping with the objective of reducing greenhouse gases, to preserve biodiversity-rich land.
Among the criteria set, biofuels must emit at least 35% less greenhouse gases than traditional fuels to be considered “sustainable”. In January 2017, this reduction in greenhouse gases resulting from the use of biofuels will have to reach at least 50% and 60% by January 2018.
On 11 September 2013, the European Parliament also decided to limit the share of 1st generation biofuels to 6% of the final energy consumed in the transport sector. This ceiling aims to reduce the impact of the development of this category of biofuels on food production. A target of 2.5% is also set for 2nd and 3rd generation biofuels.