The future of transportation will see biofuels play a much larger role than they have at any other point in history, as the world weans itself off of fossil fuels in order to try and reach net zero.
The Belem 4X pledge to quadruple the production and use of biofuels will consequently magnify both the benefits and the potential issues with certain types of biofuel production.
Biofuels vary considerably not only in terms of raw materials but in terms of production, refinement, secure storage with relief valve equipment, transportation, distribution and integration into existing fuel infrastructure.
All of these have considerable implications for the widespread use of biofuels, and this is beginning to shape the development of long-term sustainable biofuel policy.
To understand why, it is essential to explore why some biofuels are more sustainable than others in the first place and why there is so much difference in how they are produced to make them as similar as possible when entering a fuel tank.
What Makes Biofuels Sustainable?
The key reason for even using biofuels is sustainability, but what that actually means and what makes biofuels sustainable is at once relatively simple and extremely complex, and our understanding of what it means to be sustainable has become far more sophisticated.
Greenpeace describes sustainability as anything that can be continued without:
- A key resource needed to produce it running out.
- It causing harm to people, animals or the natural world.
These principles of sustainability, renewability and environmental friendliness, respectively, must be understood in combination, as many renewable resources can cause long-term environmental harm (such as firewood), whilst some highly promising alternative fuels are limited in quantity.
It is also important to look at sustainability throughout the lifecycle of biofuel, from the land used to grow or cultivate the biomass used to make fuel, transportation, the energy used for the refining processes, any greenhouse gases produced as a side effect and the exhaust fumes that come out at the end.
Much like the concept of embodied carbon in construction, whole-life sustainability in biofuel often changes the benefits of certain types of biofuel, including some widely-used types that could, in certain situations, be more harmful than fossil fuels.
Are Different Generations Of Biofuels More Sustainable?
Biofuels are typically sorted by generations, with each successive generation being more complex but also using raw materials that are better for the planet in the long run.
Whilst sorting the various biofuels is sometimes complex, here is a brief summary of each different type:
- First Generation – These are biofuels made from edible food crops, most notably sugarcane, soybean, maize, corn and palm oil.
- Second Generation – These biofuels are made with alternative plant-based sources of biomass, such as leftovers from agricultural processes, organic waste (most commonly food or oil waste) and by breaking down plants such as wood or bamboo.
- Third Generation – These biofuels typically use light-sensitive microorganisms such as algae or bacteria to generate alcohols and fats that can be transformed into fuel.
- Fourth Generation – These are biofuels made from genetically engineered microorganisms to produce higher yields of biofuel from carbon, allowing for more direct carbon capture than other types.
The general idea of each generation of biofuel is that it is more complex, expensive and initially more energy intensive until the methods are developed at scale. Early generations are cheaper but often come at the expense of sustainability, whilst later generations often require expensive research and development.
There is currently a transition from first-generation to second-generation biofuels in many countries, with used cooking oils and agricultural waste being the most popular methods as of 2026.
However, as the pushes for biofuels in Brazil and India have shown, first-generation biofuels are still very popular, and they have continued to cause debate about just how environmentally conscious and sustainable they truly are.
Are Any Biofuels Considered To Be Unsustainable?
Typically, unsustainable biofuels tend to consist less of non-renewable alternative fuels but more of fuels which have several health and policy implications when implemented at scale.
The EU describes the use of palm oil and soybean biofuels as linked to indirect land-use change, but the concept is often known as “food vs fuel” due to the perverse set of incentives that cause farmers to prioritise the use of fertile fields for fuel crops rather than food, often causing or intensifying the risk of famine and increasing food prices.
However, because the processes of producing biofuel at scale using food crops are well-known, it will remain a major part of the scaling-up process until more sustainable alternatives are developed and the costs are lowered significantly.
