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What are renewable fuels?

As set out by the Paris Agreement, 2050 is the year when society aspires to become net zero. Even though it seems a long way off, the effects of climate change are urging us to take measures to accelerate the energy transition.

These measures include the adoption of renewable fuels that can bring about great benefits for sectors where decarbonization is more complicated such as aviation, heavy-duty road freight, and maritime transportation. Given that electrification is not an alternative in these fields today, why not switch out the fuel that powers them for more sustainable options?

Renewable fuels or ecofuels are liquid fuels from non-fossil origin that are derived from circular raw materials such as non-food organic waste or renewable hydrogen and captured CO2.

One of their major strengths is that they can release up to 90% less CO2 than conventional fuels. This makes them one of the most effective solutions to cut emissions in transportation in the coming years. Their production is also environmentally friendly as they are derived from circular raw materials with a low-carbon footprint.

Renewable fuels are produced using organic raw materials such as used vegetable oil, animal fat, biomass, waste from the agri-food industry, like biogas, or forestry and farming waste, among others.

The main advantage is that these fuels can be used to power current vehicles and are compatible with the existng infrastructure, which means that we don't have to wait until new technologies are developed or a vehicle fleet is renewed before being able to start reducing emissions. In fact, the fuel we fill our tanks with at service stations today already contains more than 10% sustainable fuels. Similarly, they can be produced and distributed using industrial facilities that already exist with local raw materials, which drives the circular economy and makes it possible to diversify the energy matrix of the country in order to keep moving forward and achieve energy independence.

Illustration of a Repsol service station

Did you know that you're already getting more than 10% biofuel every time you fill up your tank with any of our fuels?

In Spain, all the fuels you'll find at our service stations already include more than 10% biofuel to comply with government standards for introducing a minimum percentage of biofuels in the total amount of road transportation fuel sales, as established in the law RD 1085/2015 for the Promotion of Biofuels. As it is a global calculation, the exact percentage of each product cannot be guaranteed.

We are working to increase this percentage.

Current renewable fuel projects

Repsol is currently developing several projects that drive our goal of producing 2 million tonnes of sustainable fuels by 2030. The use of these fuels will avoid more than 2 million tonnes of CO2 from being released into the atmosphere.

construction with a crane at the biofuels plant

First advanced biofuels plant in Spain

We've already begun construction, and it's expected to start up in 2023. The plant is located at the Cartagena industrial complex in Murcia and will use state-of-the-art technologies to manufacture advanced biofuels, such as bionaphtha, biopropane, and hydrotreated vegetable oil.

Biojet fuel will also be manufactured at this plant. This fuel, which is already being produced at the Puertollano (Ciudad Real), Tarragona, and Bilbao industrial complexes, significantly reduces CO2 emissions in the aviation sector.

Moreover, this plant will contribute to the Fit for 55 target set in the European Commission's legislative package in July 2021, which includes the RefuelEU Aviation initiative that sets the target of 63% sustainable fuel use in aviation by 2050.  

a beaker with red liquid being tested in a laboratory

Ecoplanta Molecular Recycling Solution

Furthermore, Repsol has joined Enerkem, a pioneer in technology, and Agbar, a global water and waste management specialist, in the joint venture Ecoplanta Molecular Recycling Solution (or Ecoplanta, for short). The plant in El Morell, Tarragona will transform municipal solid waste into renewable methanol to be used to manufacture new materials and avanced biofuels.

This plant, which is expected to be in operation by 2026, will process around 400,000 metric tons of non-recyclable municipal solid waste from what are called "ecoparques" — waste recovery and treatment plants — in surrounding regions. This waste will be used to produce 240,000 metric tons of renewable methane (biomethanol).

a Repsol scientist performing tests using a tablet at the Repsol Technology Lab

Rewofuel project

The Repsol Technology Lab also participates in the Rewofuel project, which consists of a conceptual design for a bio-refinery for converting plant waste into biofuels through hydrolysis.

Repsol's mission focuses on evaluating and guaranteeing that the final gasoline and aviation fuel formulas meet all requirements for marketing and use.

This project, a firm commitment to using renewable energy to drive sustainable mobility, could reduce CO2 emissions by 510,000 metric tons per year.

Types of renewable fuel

We can differ between two main types: advanced biofuels and synthetic fuels or e-fuels.

sustainable fuel barrels


Advanced biofuels are produced using organic waste (mostly vegetable oil and animal fat), and currently, they are mainly used to substitue fossil fuels in different means of transportation such as cargo trucks, ships, and planes. Some prime examples of these biofuels are hydrotreated vegetable oil (HVO) and biojet.

The use of biofuels makes it possible to reduce carbon dioxide emissions. This is given that the CO2 released while in use is equal to the amount of CO2 previously removed from the atmosphere by the raw material employed in their production. This makes them a carbon-neutral fuel.

a chemist holding a beaker with a green liquid

Synthetic fuels

Synthetic fuels, or e-fuels, are produced from basic raw materials: water and CO2. Given that the amount of CO2 released to the atmosphere during their use is offset by the amount captured for their production, they are considered zero-emission fuels. They are processed in three steps:

  1. Through electrolysis (using renewable energy sources), the oxygen and hydrogen particles of water are separated. 
  2. The oxygen is returned to the atmosphere, and the hydrogen is used in the next step. 
  3. CO2 is captured, either from the atmosphere or  industrial processes. The captured CO2 and the hydrogen previously obtained through the electrolysis phase (and called "renewable hydrogen") are used to create the fuel that can later be used in vehicles. 

These fuels have numerous benefits:

  • They're sustainable and efficient as they generate net zero emissions.
  • Existing infrastructure can be used for their transportation and storage.
  • They can be used in internal combustion vehicles.