Biofuel is a fuel produced with non-fossil organic material made from biomass (the term “biomass” covers all organic matter). Most biofuels come from agriculture so they are also referred to as “agrofuel”.
Types of biofuel
Biofuel can be made from several plant species:
Oil-producing species produce vegetable oils such as colza, sunflower, palm oil and soya. Pressed grains produce oil which is ready-to-use. However, vegetable oils are usually refined and mixed with methanol so that their properties, such as viscosity and stability, are similar to those of gas-oil. The mixture of 90 % oil and 10 % methanol which forms 10 % glycerine and 90 % vegetable oil methyl ester (VOME), is more commonly known as biodiesel.
Petrol on the other hand can be replaced by ethanol. In order to produce ethanol, plants such as sugar cane, sugar beet, corn and wheat are cultivated to extract sugar. The ethanol obtained through this process is often then transformed into ETBE (ethyl tert-butyl ether).
Fermentation of organic matter (biomethane), use of food waste (used oils, animal fats) or wood transformation can also be used to produce biofuel.
Biofuel Development
Biofuel has not been developed to replace fossil fuels entirely, but instead forms part of the search for fuel alternatives. In 1974, the United States and Brazil started to produce bioethanol to be used as fuel. Today in Brazil millions of vehicles run on pure ethanol, others run on a mixture made of 25% ethanol and 75 % traditional petrol. Biofuel arrived in Europe a little later.
The European Union has set a target for biofuel achieving a 10 % market share by 2020. In 2008, biofuel accounted for 3.3 % of fuel used for road transport in the European Union.
Why opt for biofuel?
Biofuel combustion usually pollutes less than that of fossil fuels. It generates little or no nitrogen oxides and sulphur oxides (NOx and SOx). The biggest environmental gain is the reduction of carbon dioxide (CO2) emissions, which contribute to the Greenhouse Effect and global warming. One tonne of biodiesel saves 2.1 tonnes of CO2 and one tonne of ethanol saves 1.4 tonne of CO2. A 1 % use of biofuels avoids 1 million tonnes of CO2 emission into the atmosphere.
Mixed views
The energy efficiency of biofuel is currently being debated. Energy efficiency of a given type of fuel takes into consideration the energy needed to produce the fuel, as well as the energy the fuel itself produces. An energy efficiency ratio above 1 means that the energy the fuel provides is higher than the energy required to produce it. The energy efficiency of bioethanol and biodiesel is almost 2, and almost 4 for pure vegetable oil. However, it is closer to 1 for ETBEs.
Risks
This said, biofuel use is controversial. Biofuel industrial development is currently being blamed for generating competition in land use. This competition could contribute to increasing prices for agricultural raw materials, or else cause local imbalances where countries decide to significantly shift their agriculture towards agrofuel production. Agrofuel is also normally cultivated using intensive methods which increases water and soil pollutants, such as nitrates and plant protection products.
Moreover, the energy efficiency and low GHG emission levels for biofuel are being debated. Land use change has a significant impact on this, since converting forest into farmland has a hugely negative effect on greenhouse gas concentration in the atmosphere.
Legal framework needed
The environmental impact of agriculture can be reduced by applying various criteria, such as those proposed by the European Directive.
Industry and researchers are now working on fuels known as “second-generation biofuels”, which will be more efficient and more environmentally-friendly. They are produced in part or entirely with biomass components such as lignin, cellulose and hemicellulose, rather than just plant energy reserves such as starch and oil. The advantages of second-generation biofuels include more resources (wood, straw, dedicated crops, vegetable waste), low-cost raw materials and no competition with the food industry.
Today, even third-generation biofuels from microalgae are being considered.
