The energy transition does not depend on a single solution. In order to reduce emissions from industry, transport and power generation, it will be necessary to combine technologies that can store, transport and use energy more efficiently and sustainably. This is where energy carriers come into play.
An energy carrier is a medium that enables previously obtained energy to be stored, transported or supplied. In other words, the original source of energy is not necessarily important; what matters is how that energy reaches the point of consumption.
Examples of energy carriers include electricity, hydrogen and certain synthetic fuels. The development of energy carriers is closely linked to the growth of renewable energy, industrial decarbonisation, and the European target of achieving climate neutrality by 2050
Green hydrogen is produced through the electrolysis of water using electricity exclusively from renewable sources, such as solar or wind power. During this process, water is split into hydrogen and oxygen without producing any direct carbon dioxide emissions.
For this reason, green hydrogen is regarded as an energy carrier because the original energy comes from the sun or wind, is converted into electricity, and is then stored in the form of chemical energy in hydrogen. Hydrogen therefore makes it possible to store, transport and use this renewable energy in places or applications where using electricity directly is more difficult.
Hydrogen therefore makes it possible to store, transport and use this renewable energy in places or applications where using electricity directly is more difficult
In this respect, its strategic importance goes beyond simply replacing conventional fuels. According to the latest Global Hydrogen Compass 2026 report, projects with a capacity of 6.9 million tonnes of low-carbon hydrogen have already been approved, are operational, or are under construction.
Furthermore, green hydrogen is essential for producing alternative fuels, such as e-fuels for aviation and maritime transport. This expands its role in the future energy system.
Technological advances, increased electrolysis capacity and falling renewable energy costs could boost the competitiveness of renewable hydrogen in the coming years. Spanish projects in the latest European Hydrogen Bank auction have already secured an average price of €5.3/kg. The price is gradually reduced each year.
Biomethane is a renewable gas obtained by purifying the biogas produced by the decomposition of organic matter. Waste from agriculture, livestock, urban areas and sewage treatment plants can be converted into a fuel with a composition virtually equivalent to that of natural gas.
In this case, the energy is originally contained in the organic matter. Biological and treatment processes make it possible to convert this energy into biogas and subsequently into biomethane – a gas that can be stored, transported, and used as a fuel. Therefore, biomethane can be regarded as a renewable fuel and an energy carrier because it makes the energy contained in waste available for various uses.
One of its main advantages is that it can be injected directly into the existing gas network and used with existing equipment – including boilers, industrial facilities and gas-fuelled vehicles – without the need to develop new distribution networks.
It is particularly suitable for industrial processes requiring high-temperature heat, flexible electricity generation, and heavy-duty transport using compressed (bio-CNG) or liquefied (bio-LNG) biomethane.
The European Union’s REPowerEU plan aims to produce 35 billion cubic metres of biomethane per year by 2030. This initiative positions biomethane as a renewable alternative to reduce dependence on fossil gas, utilise local resources, and strengthen energy security.
Liquefied natural gas (LNG) is natural gas that has been cooled to approximately -162°C. At this temperature, it turns into a liquid, reducing its volume by a factor of around 600. This makes it easier to store and transport over long distances.
With LNG, the concept of an energy carrier differs in that no new energy is produced; the energy comes from natural gas, which is of fossil origin. Liquefaction enables this energy to be converted into a more manageable form so that it can be transported to where it is needed.
Compared with fuel oil or coal, LNG can reduce emissions of particulate matter, sulphur oxides and certain nitrogen oxides. However, its role in the energy transition should be understood as a transitional solution for specific applications, particularly in maritime transport, certain industries, and energy supply in remote areas – as other sustainable energy carriers become more widely available and competitive.
E-fuels, also known as synthetic fuels or electrofuels, are produced by combining renewable hydrogen with carbon dioxide captured from industrial processes or directly from the atmosphere, using various chemical synthesis processes.
Depending on the process used, the end product may be synthetic petrol, synthetic diesel, sustainable aviation kerosene, methanol or synthetic gas.
E-fuels are also energy carriers because they enable renewable electricity to be converted into chemical energy. Rather than using the electricity directly, it is used to produce hydrogen, which is then used to produce a synthetic fuel that can be stored, transported and used wherever and whenever it is needed.
Their main advantage is that they can be used with most existing engines and infrastructure, reducing the need to replace entire fleets of vehicles or storage systems.
E-fuels are considered relevant for sectors where electrification faces significant limitations, such as commercial aviation or international shipping
E-fuels are therefore considered particularly relevant for sectors that are difficult to electrify, such as commercial aviation, international maritime transport and certain heavy-duty road transport applications.
However, the main challenge for e-fuels remains the high level of renewable electricity required to produce them, which currently affects their cost and availability.
Spain is particularly well placed to lead the development of several of these energy carriers. The country’s abundant solar and wind resources facilitate the production of renewable hydrogen at competitive costs, while the substantial amount of agricultural, livestock and urban waste provides significant opportunities to increase biomethane production.
The energy transition will not depend on a single technology. Each energy carrier offers value in different applications: some enable the storage of renewable energy, some utilise organic waste and facilitate the transport of energy, while others help to reduce emissions in sectors where direct electrification is not always feasible.
In this context, green hydrogen is set to become a key ally for industry and the production of synthetic fuels, while biomethane will enable progress towards a circular economy by utilising local resources. Natural gas will continue to play a transitional role in certain applications, and e-fuels will offer a complementary route to decarbonising heavy-duty, maritime and air transport.
The key will be to combine these solutions efficiently in line with the needs of each sector in order to move towards a more sustainable, secure and competitive energy system.
