Whether for lack of infrastructure, strict regulationsocial perception, or by many other factors, electrification is a process that is advancingbut very slowly. Meanwhile, more than 20 million diesel and gasoline vehicles continue to circulate in Spain, many of them more than a decade old (or two). However, there are solutions that try to make this energy transition more bearable, and one of them involves the use of renewable fuels.
What exactly are these fuels?. They don’t have a single drop of oil. They are produced from organic waste such as used cooking oils, animal fats, forest waste or crop remains. The catalytic hydrogen generation process transforms these wastes into fuels with properties similar to those derived from petroleum, but with a key difference: the CO₂ they emit when burned is the same as that which plants have previously absorbed from the atmosphere.
Here we would therefore speak of a closed cycle, unlike fossil fuels, which release carbon stored underground for millions of years.
Emissions. Repsol states that its Nexa diesel can reduce net CO₂ emissions by up to 90% compared to conventional diesel, while your Efitec Nexa gasoline discount more than 70%. In this case, although the engine continues to emit CO₂, it was already in the atmosphere before being converted into fuel.
However, there is a nuance: nitrogen oxides (NOₓ) continue to be generated during combustion, because they come from nitrogen in the air when exposed to high temperatures. And for now, studies show conflicting results, with some indicating slight increases in NOₓ with certain biofuels, while others like the US National Renewable Energy Laboratory they conclude that renewable diesel reduces both CO₂ and NOₓ. What is consistent is the reduction of particles and soot.
Full compatibility with current cars. This is probably its biggest practical advantage. Any diesel or gasoline vehicle can use these fuels without technical modifications. There is no need to change the engine, adapt the tank, or install new pumps at gas stations.
In the case of Repsol, its Nexa diesel also complies with the European standard EN 15940 for paraffinic fuels, and Efitec Nexa gasoline with EN-228. In addition, the company ensures that, thanks to its high cetane number, it improves combustion, reduces engine noise and has a cleaning effect on the injection system.
Where to find them in Spain. Repsol clearly leads the deployment, with more than 1,000 stations that offer Nexa diesel and with the goal of reaching 30 stations with Efitec Nexa gasoline by the end of the year. BP too offers HVO (hydrotreated vegetable oil) in strategic locations such as Tafalla, Getafe, Villacastín Norte or Olaberria, although its network is more limited and is oriented towards professional transport.
To locate them, the most practical thing is use web search engines of each company, since they include filters to find gas stations that offer renewable fuels.
It is worth remembering that the conventional diesel sold at practically all gas stations in Spain already contains up to 7% biodiesel (B7 label), but it is not comparable to a 100% renewable fuel if we stick to emissions.
Cost and availability. Price is one of the main obstacles. Nexa diesel costs approx. 10 cents more per liter than conventional diesel, placing it in the range of premium fuels. Renewable gasoline follows a similar trend. Furthermore, although Repsol has expanded its network, coverage remains limited outside large urban centers and main corridors, especially in terms of renewable gasoline.
Industrial production. Repsol produces renewable diesel in its Cartagena refinery and 100% renewable gasoline at the Tarragona plant. The company assures that it has been researching these processes for more than twenty years in collaboration with Honeywell. In 2026, the opening of a new facility in Puertollano with capacity for more than 200,000 tons per year is planned.
Who is using them already?. In addition to the fact that anyone can now go to a Repsol gas station to try these fuels, their use has transcended commercial vehicles. And they have been tested in competitions like the Dakar Rallyand even sustainable fuels are used on commercial flights. Also transport companies such as Scania, Alsa or Grupo Sesé have signed agreements for adoption.
An intermediate solution. The current European regulations The CO2 emissions test for new vehicles measures emissions from the tailpipe. With this approach, the result is zero for an electric car, but not for one that uses renewable fuel, even if it is carbon neutral in its entire life cycle (from production to consumption). It is for this reason that the industry and defenders of these fuels are asking for a change in the methodology so that the complete life cycle of the fuel is considered.
Repsol and other players in the sector They ask for adapted taxation and long-term objectives that provide stability to investments. The Spanish mobile fleet has an average age of 14.5 years and it has more than eight million vehicles that are more than two decades old, according to data from ANFAC (Spanish Association of Automobile and Truck Manufacturers). Therefore, renewable fuels could be an intermediate alternative in this stage of energy transition, especially since they do not leave millions of drivers behind.
Cover image | engin akyurt
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