Ammonia and methanol as hydrogen derivatives – safe conveying for storage and transportation of green energy

 

The energy transition needs storage

The decarbonisation of energy supply is a political decision and, technically, has no alternative. Because wind and solar power fluctuate strongly, growing gaps arise between generation and demand: on sunny or windy days, supply exceeds demand, while periods of low wind and sun (“dunkelflaute”) can cause shortfalls. Plants are already being curtailed at times to relieve the power grids.

Storage solves this problem by absorbing surpluses, preventing curtailment and relieving the grid. Long-duration storage is essential for security of supply – just as gas storage is today.

Hydrogen as an energy carrier—great potential, great challenges

Hydrogen is regarded as a key element for the long-duration storage of renewable energy. Electrolysis chemically binds surplus electricity, making it flexibly usable.

Although hydrogen has a high gravimetric energy density, it requires large volumes. Economic transport therefore requires high pressures or liquefaction. Liquid hydrogen must be stored at around -253 °C, which places high demands on containers, insulation and the entire infrastructure.

A further factor is the molecule’s high volatility. Hydrogen diffuses through seals, flanges and materials considerably more easily than many other energy carriers. This significantly increases the requirements for tightness and safety.

Another important aspect is hydrogen embrittlement. Unalloyed and low-alloy steels in particular can lose strength under the influence of hydrogen, creating additional requirements for material selection and design.

These challenges have led to a worldwide search for alternative ways to make hydrogen easier to store and transport.

properties of H2	challenges for plants and systems
low volumetric energy density	high storage volume requirement
volatility	very stringent tightness requirements
liquefaction	-253 °C required
hydrogen embrittlement	highest material requirements

 

Hydrogen derivatives as a bridge between production and use

One promising solution is to chemically bind hydrogen to other molecules, making it storable and transportable.

Among the various options, ammonia and methanol are currently being discussed particularly intensively. Both substances are already established global commodities, with existing production sites, storage facilities, tank terminals, ships and logistics networks – even if not necessarily yet in the context of energy carriers.

Ammonia – a well established hydrogen carrier with high energy density

Ammonia (NH₃) is one of the most promising hydrogen derivatives. The molecule contains no carbon and has a high hydrogen density. This makes ammonia suitable both as a hydrogen carrier and as a potential energy carrier for applications in industry, energy supply and shipping.

A key advantage is that ammonia is already produced, stored and transported in very large quantities today. The global infrastructure for production, transport and handling already exists.

At the same time, green ammonia is still at an early stage of industrial scale-up. Global ammonia production today still relies predominantly on fossil feedstocks, in particular natural gas and coal gasification. Low-emission production processes currently account for only a very small share of global output. Precisely for this reason, green ammonia is gaining strategic importance as a derivative and as a storage and transport solution for green hydrogen.

Ammonia is gaseous at room temperature and is usually liquefied under pressure or at temperatures below its atmospheric boiling point of around -33 °C. If liquid ammonia escapes from a plant or pipeline, it evaporates within a very short time. This releases large quantities of toxic gas, while the rapid evaporation can also cause strong local cooling.

Ammonia is also highly toxic and strongly corrosive. A release can endanger people, plant and the environment. In addition, flammable mixtures can form at concentrations of roughly 14 to 32 volume percent in air.

For the safe handling of ammonia, avoiding even the smallest leaks is therefore absolutely essential.

 

Ammonia at a glance (NH3)
carbonfree hydrogen carrier
boiling point	-33 °C (-27,4 °F)
properties relevant for storage and transport	toxic and corrosive
usability/application	hydrogen storage with a high hydrogen component
existing infrastructure	globally established logistics infrastructure

 

Methanol – a liquid energy carrier with existing infrastructure

Alongside ammonia, methanol (CH₃OH) is one of the most interesting hydrogen derivatives.

Methanol is already one of the world’s most important base chemicals today. Among other things, it is used in the production of formaldehyde, acetic acid, MTBE, DME, pharmaceutical products and numerous other chemicals. It also plays an important role as a solvent, antifreeze and energy carrier.

Unlike ammonia, methanol is liquid at ambient temperature. This means it can be stored, transported and handled in a similar way to today’s fuels.

So-called e-methanol in particular is gaining importance for the hydrogen economy. It is produced from renewable hydrogen and biogenic or captured CO₂. This allows renewable energy to be stored in an easy-to-handle liquid energy carrier.

At the destination, methanol can either be used directly or converted back into hydrogen via reforming processes.

Methanol, however, also places demands on plant engineering. The substance is toxic, highly flammable, and forms explosive mixtures with air already at concentrations of roughly 6 to 36.5 volume percent. In addition, its low viscosity and specific requirements for materials – and particularly for sealing systems – must be taken into account.

 

Methanol at a glance (CH3OH)
hydrogen carrier with one carbon atom
state of matter at ambient temperature	liquid
boiling point	64,7° C (148,46 °F)
properties relevant to storage and transportation	toxic and highly flammable
usability/application	e-fuels and hydrogen storage
existing infrastructure	useable and scalable

 

Safe pumping as a central prerequisite 

 

 

The success of ammonia and methanol concepts does not depend on production alone. While ammonia can be produced from green hydrogen and virtually unlimited atmospheric nitrogen, methanol additionally requires a sustainable carbon source. For e-methanol, biogenic CO₂, captured industrial CO₂ or CO₂ from the air are the main options. It is therefore not carbon as such that is scarce, but rather a sustainable, concentrated and economically available source of CO₂.

For both approaches, the safe storage, loading and pumping of the media along the entire value chain is of particular importance.

Pumps play a central role here. They convey the media from the production site via tank farms and terminals through to ships, pipelines, crackers, reformers and consumers.

Typical pumping tasks arise throughout the entire process chain. These include filling and emptying tanks, loading and unloading ships, transfer at pipeline stations, and the operation of loading facilities, port and terminal installations. Equally important is the reliable supply of reforming and cracking plants, as well as intermediate storage and recirculation in power-to-X facilities. A failure or a leak can have far-reaching consequences and compromise the safety, availability and economic viability of the entire plant.

This is particularly evident in the case of green ammonia. The process chain begins with renewable electricity used for electrolysis, while nitrogen is extracted from the air. Hydrogen and nitrogen are then converted into ammonia via the Haber-Bosch process. This is followed by storage, handling and transport processes via tank farms, loading stations, export and import terminals, transfer stations and, where applicable, cracker plants. There, ammonia is split back into hydrogen and nitrogen at the destination, making hydrogen available exactly where it is needed.

From a pumping-technology perspective, particularly relevant tasks arise in these sections: tank filling, tank emptying, ship loading, pipeline transfer, intermediate storage, and the supply of cracking plants. Ammonia can be used either directly – for example in fertiliser production, in the chemical industry, in shipping, in power plants or in industrial furnaces – or serve as a hydrogen carrier. Throughout this entire value chain, tight, reliable and media-compatible pump systems are a central prerequisite for safety, availability and economic viability.

 

 

Special requirements for pumps in ammonia and methanol applications

The properties of ammonia and methanol place high demands on pumps, materials and sealing systems. What matters is not the hydraulic design alone, but above all the safe management of the respective substance properties under real plant operating conditions.

With ammonia, particular challenges arise from the high vapour pressure, the low boiling point and the high toxicity. Even small changes in pressure or temperature can promote flashing and cavitation. At the same time, even the smallest leaks must not be allowed to reach the environment, since escaping ammonia evaporates rapidly and can form dangerous gas concentrations.

Methanol presents different, but equally demanding, requirements. Due to its low viscosity, reliable lubrication, stable operation and suitable sealing systems are particularly important. In addition, there is high flammability, the possible formation of explosive atmospheres, and the need to consistently match materials and elastomers to media compatibility.

For both media, the same principle applies: the pump must be designed to be permanently tight, made of suitable materials, and operationally safe. Tightness, explosion protection, temperature management, NPSH considerations, monitoring and ease of maintenance thus become central criteria. Only if these requirements are consistently taken into account can ammonia and methanol be pumped safely, reliably and economically along the entire power-to-X value chain.

Hermetically sealed pump technology as a key technology

Against this backdrop, hermetically sealed pump concepts are becoming increasingly important.

In magnetically coupled pumps, torque is transmitted contact-free via a magnetic coupling. The product chamber is completely separated from the environment by a hermetically sealed containment shroud.

Unlike pumps with mechanical seals, there is no dynamic shaft seal acting as a potential leak path. This significantly reduces the release of toxic, flammable or environmentally critical media.

For operators, this brings additional benefits: hermetically sealed pumps increase plant safety, reduce emissions and lower maintenance effort. At the same time, they contribute to higher plant availability and support ESG and sustainability goals. Viewed over the entire life cycle, they can also significantly reduce operating costs.

Conclusion

The energy transition requires not only the generation of renewable energy, but also high-performance solutions for storage, transport and global availability.

Ammonia and methanol are emerging as important hydrogen derivatives, as they enable the long-term storage and worldwide transport of renewable energy while also making use of partially existing infrastructure.

However, the special properties of both media place high demands on plant and pumping technology. Safety, tightness and availability become decisive success factors.

Hermetically sealed magnetically coupled pumps make an important contribution here. They help operators minimise leaks, emissions and safety risks, thereby creating an essential prerequisite for the successful build-out of a hydrogen and power-to-X infrastructure.

 

Article in german magazine ChemieTechnik

This article was published in a shortened version in german language in issue 05/2026 of ChemieTechnik: Ammoniak und Methanol sicher fördern