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Are biofuels safe for the environment?
Did you know that the first internal combustion engine developed by Nikolaus Otto in 1876 ran on ethanol? And that the famous Ford T also ran on such alcohol? Produced from beet sugar or cereals, ethanol is one of the “biofuels” obtained from biomass. Incorporated into fossil fuels, they help reduce the environmental impact of the transport industry, which is responsible for 25% of CO2 emissions worldwide. But what is the reality? Are biofuels a viable alternative to fossil fuels? Do they have hidden environmental consequences?
An overview of biofuels
The prefix “bio” does not mean that biofuels are environmentally friendly, but that they are derived from organic plant material such as beet, rapeseed, sunflower, wheat, maize or agro-forestry waste. Two kinds of biofuels can be produced from these biomass sources:
- Bioethanol, an alcohol made from the fermentation of plant sugars or starch, which can be used in petrol engines
- Biodiesel, intended for diesel engines and produced from vegetable or used oil or animal fats.
In both cases, these biofuels are added to traditional fuels, such as unleaded 95 and 98, without requiring any changes to the distribution network or vehicles. The result is a reduction in greenhouse gas emissions of up to 60 % compared to the use of fossil fuels alone.
A contrasted environmental record
This growth is driven by the United States, followed closely by Asia and Europe. The development of bioenergy meets environmental objectives that are the subject of proactive policies, such as the legislative package on climate and energy set by the European Union.
However, these positive benefits are outweighed by the environmental impact of growing the agricultural feedstocks needed to produce biofuels. As Timothy D. Searchinger, a researcher at Princeton University's Centre for Energy and Environmental Policy Research, points out: “A quarter of CO2 emissions come from land-use change, deforestation and agriculture. When we produce biofuels, we are simply transferring the problem from fossil fuels to land use”.
The land used to grow crops for biofuels is land that is not used for food. Increasing demand for biofuels also means finding new land, which leads to increased deforestation and the depletion of natural ecosystems, with a direct impact on global warming. A study by Environmental Action Germany highlights the environmental costs of biofuels in Germany.
On the one hand, biofuels mixed with fossil fuels prevented the emission of 9.2 million tonnes of CO2 in 2020.
On the other hand, if the land where these monocultures are grown were covered with natural vegetation, it would be able to store 16.4 million tonnes of CO2 per year on average. As Joe Fargione, science director for the North American region of the environmental organization The Nature Conservancy, sums up: “If you imagine a prairie and a cornfield, there's a lot more carbon in the prairie soil. When you convert a grassland into a maize field, that carbon has to go somewhere. It goes into the air as carbon dioxide and contributes to climate change. Any biofuel that results in the clearing of natural ecosystems will cause a 'carbon debt' that will take years to pay off”.
What is the future for biofuels?
If the use of biofuels therefore has counterproductive effects, by capturing less CO2 than ecosystems left untouched would, how can we meet the challenge of sustainable mobility? One way is to focus on so-called second-generation biofuels that do not compete with food crops. They are produced from agricultural residues, forestry waste or used cooking oil and could represent up to 45% of the biofuels consumed in 2030 according to the IEA. Provided that new technologies are developed to increase efficiency and lower production costs. The use of these alternative fuels is of particular interest to the aviation sector: when mixed with paraffin, they could reduce greenhouse gas emissions from air traffic by 50 to 90%. There is also talk of third-generation biofuels, produced from micro-algae.
In order to assess the environmental impact of biofuels, each stage must be taken into account, from the cultivation of the raw plant materials to their final use, via the transformation processes. In addition, many researchers are reminding us of the need to rethink our travel habits and to rely on a range of solutions in order to make a real transition. A transition capable of meeting the challenge of sustainable mobility.