The energy transition is not just about generating more renewable electricity; it is about delivering it to the right place at the right time. Wherever viable, a direct electrical connection is usually the most efficient option because it avoids conversion losses. Power-to-fuel is not intended as an across-the-board replacement for cables: it complements them when moving electrons proves insufficient, unfeasible, or too costly.

For more than a century, tankers, pipelines, and gas grids have connected production centres with demand hubs thousands of kilometres apart. The challenge now is whether we can do something similar with renewable energy: convert electricity from wind or solar into a usable molecule, store it, and ship it wherever it is needed.

That is the core idea behind power-to-fuel. It starts from a familiar premise: fuels store chemical energy and can be moved in a tank, a pipeline, or a ship. An electrofuel retains that function, but relies on electricity as its primary energy source. This is why they are also called e-fuels—the ‘e-’ prefix pointing to their electric origin. Green hydrogen can be used directly or serve as the feedstock to produce green e-methanol, green ammonia, and other synthetic fuels.

What you will learn in this article:

• Why generating green energy is not enough
• When a cable is no longer the best option
• What power-to-fuel actually is
• Green hydrogen: the foundational molecule
• Pipelines, ships, and storage: the logistics of molecules
• Methanol and ammonia: fuels that double as carriers
• Why power-to-fuel matters
• Limitations: a targeted solution for specific cases
• A technological, economic, and logistical race

The prime areas for generating renewable energy do not always coincide with major industrial or urban centres. Many regions enjoy abundant sunshine, constant wind, or ample available land, yet sit far from the ports, factories, and transport corridors where demand is concentrated. Even offshore wind farms can produce green hydrogen through seawater electrolysis alongside electricity.

This poses a strategic choice: is it better to produce hydrogen close to the end user or import it from places where renewable electricity is cheaper? The answer depends on electricity costs, distance, volumes, available infrastructure, and the efficiency of each conversion step.

Importing green energy in the form of molecules makes sense when producing it remotely, converting it, transporting it, and using it at destination proves more competitive or viable than generating it locally or connecting it via a power line. The renewable resource and supply chain must offset the losses, capital expenditure, and complexity involved.

Before turning electrons into molecules, a direct electrical link must always be assessed. High-voltage lines, including high-voltage direct current (HVDC) cables for long distances, carry large amounts of bulk power at high efficiency. They are generally preferred whenever there is a viable route, steady demand, and a grid capable of receiving the power.

A direct cable connection can cease to be practical when distances and costs escalate; when routes cross deep waters, protected areas, or multiple jurisdictions; when the receiving grid lacks capacity; or when energy must be stored for weeks or months. Utilisation rates also matter: expensive infrastructure that only carries intermittent surpluses can struggle to pay for itself.

There is no universal distance beyond which cables stop working. The choice depends on power capacity, routing, operating hours, losses, permitting, and existing infrastructure. Power-to-fuel makes sense when storing energy, transporting it by ship, or using it as a fuel offsets the energetic and economic costs of conversion.

Power-to-fuel brings together technologies that convert electricity, preferably renewable, into hydrogen and derived synthetic fuels. The first step is typically water electrolysis: an electric current splits water into oxygen and hydrogen. If the electricity is renewable, the output is considered green hydrogen.

One of the most advanced examples of electrolysis in action is ACCIONA’s VALLE H2V NAVARRA project, which will produce 3,700 tonnes of renewable hydrogen per year for local industrial consumption.

For instance, ACCIONA Energía’s biomass plants in Spain produce nearly 900,000 tonnes of biogenic CO₂ each year—a valuable resource for producing synthetic fuels like methanol. The company is already assessing various initiatives to capture and condition this , combining it with renewable hydrogen to give it a productive new purpose.

The logic is akin to ‘bottling’ renewable energy. It does not literally store the wind or transport the sun, but part of their energy is locked into chemical bonds capable of travelling by ship, sitting in a storage terminal, or powering processes that are difficult to electrify.

Green hydrogen can serve as a fuel, an industrial feedstock, and an energy store. It is used in fuel cells, metallurgy, and chemical production, and provides the base for other renewable fuels.

Its main drawback is physical: it contains high energy density by mass, but very low energy density by volume. Transporting it requires increasing that density through compression, liquefaction, or conversion into another chemical compound.

Compressing it demands high-pressure tanks and consumes energy. Liquefying it increases density, but requires cryogenic cooling down to around -253 °C. Converting it into methanol or ammonia can ease logistics, though unpacking the hydrogen later adds losses and complexity. There is no one-size-fits-all solution.

The supply chain comprises three stages: ‘packing’ the hydrogen through compression, liquefaction, or chemical conversion; transporting it by pipeline, ship, or tanker lorry; and ‘unpacking’ it to obtain the form of energy needed by the end user.

Over short distances and with large, steady demand, pipelines can be efficient, though they involve heavy upfront investment. Over medium or long maritime routes, ships become far more attractive for moving bulk energy between exporting and importing regions.

The choice depends on distance and scale. Pipelines generally hold the advantage on short runs; liquid hydrogen (LH₂) can compete on long routes and large volumes; and compressed hydrogen (CH₂) or chemical vectors fit well in intermediate scenarios. 

E-methanol combines green hydrogen with captured CO₂. Its logistical strength is that it remains liquid at ambient temperatures, making it easy to store, load onto tankers, and handle using existing infrastructure. It can be used directly as a fuel or converted back into hydrogen, although that second step consumes energy.

Green ammonia combines hydrogen with nitrogen from the air. It can be transported by ship and benefits from an established global industry. As an energy carrier, it packs considerable hydrogen per unit volume and is stored as a liquid under far milder conditions than liquefied hydrogen.

The issue arises when pure hydrogen is needed at destination: ammonia cracking consumes energy and requires dedicated plant equipment. For that reason, methanol and ammonia are especially attractive when consumed directly as a fuel or feedstock. If they need to be reconverted, the round-trip efficiency of the entire chain must be evaluated carefully.

Power-to-fuel can address three specific challenges:

• It enables long-duration storage of surpluses from variable renewable generation that depends on the sun and wind.
• It facilitates bulk energy transport between regions with abundant renewable resources and industrial demand centres that cannot cover their needs cost-effectively through domestic production.
• It can help decarbonise hard-to-abate sectors such as maritime transport, aviation, high-temperature industrial heat, and the chemical industry. In these areas, renewable fuels complement direct electrification rather than replacing it.

In carbon-based e-fuels, such as e-methanol, the origin of the CO₂ is decisive. Capturing, transporting, and reusing carbon can help close the loop, but it adds energy consumption, costs, and technical demands.

The primary limitation is efficiency. Electrolysis, synthesis, compression or liquefaction, transport, and potential reconversion all consume energy. As a result, using electricity directly usually requires far less renewable generation than converting it into hydrogen or synthetic fuel and back again. Where an application can be reasonably electrified, the direct path should take priority.

In other words, power-to-fuel is particularly useful where direct electrification is not feasible, or where energy must be stored for long periods or carried over great distances.

There are also economic and material constraints. Scaling requires vast volumes of renewable electricity, electrolysers, treated water, synthesis plants, storage tanks, marine terminals, and safety standards. For carbon-based fuels, an adequate source of non-fossil CO₂ must be secured. To maximise emission cuts, both the power source and the origin of that carbon are critical.

High costs, missing infrastructure, and losses during transport or hydrogen recovery remain challenges. Ammonia demands tight handling controls due to its toxicity; liquid hydrogen requires cryogenic temperatures; and carbon-based synthetic fuels release CO₂ again upon combustion, even if that carbon was previously captured. Unlike fossil fuels, however, that carbon can come from captured and recycled CO₂ rather than introducing new fossil carbon into the atmosphere.

Power-to-fuel does not aim to replace direct electrification in every application. Its clearest role lies in long-duration energy storage, maritime energy transport, and sectors that strictly require a chemical molecule as a fuel or raw material and cannot easily plug into the grid. It is a complementary tool, not a universal one.

Power-to-fuel brings together solutions that both compete and complement one another. Hydrogen can serve as the baseline; methanol and ammonia as liquid carriers; pipelines as steady corridors; ships as transoceanic links; and port terminals as the hubs of a reconfigured energy landscape.

The race will not be won through chemistry alone. It will take infrastructure, clear regulation, bankable contracts, safety standards, investment, and lower costs. Furthermore, green fuels should be reserved primarily for hard-to-abate applications where no direct alternative exists to deliver the same outcome with lower energy consumption.

At heart, power-to-fuel offers a straightforward principle: when we cannot deliver renewable electricity directly to where it is needed, or when we must store it for extended periods, we can turn it into a molecule that travels and stores more effectively. ‘Bottling the wind and transporting the sun’ captures a vital part—though not the entirety—of the clean energy transition..

Sources:

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