Sustainable fuels: what alternatives are currently being considered?
Sustainable fuels, produced from renewable sources, are emerging as the key solution to reduce emissions and move towards a cleaner energy model.
Traditional fossil fuels - such as oil, natural gas and coal – are the primary causes of global warming and climate change. When burned to generate energy, they release carbon dioxide and other greenhouse gases that accumulate in the atmosphere, trapping heat and disrupting the balance of the planet's climate.
According to data from the European Parliament, economic activity in the European Union generated around 3.6 billion CO₂ equivalent tonnes in 2021. Against this background, the EU bloc has committed to reducing its greenhouse gas emissions by 55% by 2030, as a decisive step towards its goal of zero emissions by 2050. In this context, energy transition is no longer a matter of choice, but rather an urgent necessity to build a cleaner, more ethical and sustainable model.
What alternatives are being considered?
Sustainable fuels offer cleaner energy sources that contribute to a more resilient and ecofriendly energy system. They also support the circular economy by using organic waste or by-products and help to significantly reduce greenhouse gas emissions.
What are the main challenges?
As these are relatively recent alternatives, there is still no unified global regulatory framework to facilitate the implementation of these sustainable fuels. Furthermore, their production cost hinders their competitiveness unless economic incentives are provided, and there are doubts regarding their scalability, as their production depends on natural resources such as water and food crops, which are essential for human life.
Sustainable fuels offer a cleaner, more ethical and resilient energy model. Although they still face significant challenges, such as the lack of global regulation, production costs and doubts about their scalability, their potential to reduce emissions and use resources more efficiently makes them the main alternative in order to build a sustainable future.
Among the main options that are currently available, the following stand out:
Sustainable fuels: what alternatives are there?
Biofuels
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Also known as drop-in fuels, they are characterised by the fact that they can be used in internal combustion engines without the need for major modifications. They are produced from biomass by biological, chemical or thermal processes, and are currently the most widespread and widely used category among green fuels.
These fuels are made from organic waste such as spent vegetable oils, animal fat or by processing raw materials such as corn or sugar cane. This group includes bioethanol, biodiesel and biogas, among others.
In Spain, there are already policies and regulations that promote their use, for example, in the field of transportation. Spanish Royal Decree 1085/2015 for the Promotion of Biofuels mandates that fuels offered at service stations must contain at least 10% biofuels.
Renewable hydrogen
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Also known as green hydrogen, it is obtained sustainably through electrolysis, a process that separates hydrogen and oxygen molecules from water, releasing the latter back into the environment. One of its great advantages is that it can be stored and transported relatively easily, allowing it to be used in many fields: from transportation and energy generation to air conditioning and the production of synthetic fuels, as we will see below.
Synthetic fuels
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Also known as e-fuels, these are produced from renewable hydrogen combined with carbon dioxide captured from the atmosphere. Their composition makes them very similar to conventional fossil fuels, but with one key difference: they represent a much more sustainable alternative, as they contribute to a significant reduction in greenhouse gas emissions. The synergy between green hydrogen and atmospheric CO₂ produces synthetic fuels capable of powering heavy transportation vehicles such as aircraft, ships or industrial vehicles. Among the most prominent are e-methanol and green ammonia.
