Decarbonising or de-fossilising the economy on the path to climate neutrality requires a transition to green technologies across the energy, industry, construction, and mobility sectors. Due to the volatility of electricity generation from renewable energies such as wind and solar power, reliable and cost-effective storage and transportation options for large amounts of energy are of key importance. Hydrogen plays a crucial role for these applications; it can be stored and transported and is a key driver for the decarbonisation of the economy, industry, and energy supply, which contributes to overcoming the climate crisis.
However, it is necessary to take a holistic view on the hydrogen value chain to ensure that technological transformations are successfully implemented worldwide. Furthermore, an integrated and aligned view of the individual components of the value chain is important to ensure optimal results in terms of overall costs. Only with detailed knowledge of the individual processes from production to storage, transport, and distribution to the end-user, can the best solutions be achieved. As several components are working together in an integrated system, well-designed communication, control, and automation is of paramount importance. An own automation company which takes care of the process logic control of the individual components makes sure they are well aligned under one master automation roof. Additionally, the monitoring for asset management, predictive maintenance and accelerated troubleshooting are integrated here too.
Production of hydrogen
The method and technology used for hydrogen production depend directly on the energy source of choice. Currently, methane converted into hydrogen by steam reforming (SMR) is the most common source. This process produces around 10 t of carbon dioxide (CO2)/t of hydrogen, which corresponds to around 300 g/kWh. An alternative method is pyrolysis, in which methane is passed through molten tin in a bubble column reactor. This process produces elemental carbon as a by-product. By using certified biomethane, the CO2 footprint of these processes can be significantly reduced, enabling the production of ‘green’ hydrogen. However, direct CO2 emissions cannot be completely avoided.
Electrolysis produces hydrogen without direct CO2 emissions. There are various technologies that differ in terms of maturity and respective advantages and disadvantages. However, what all processes have in common is that water is split into hydrogen and oxygen molecules through an electrochemical reaction. The two most common methods are alkaline electrolysis (AEL) and proton exchange membrane electrolysis (PEM).
In PEM electrolysis, high-purity water is split using precious metal catalysts. The membrane used prevents the resulting gases from mixing. This ensures high gas purity at a discharge pressure of around 30 bar. In addition, PEM can effectively follow a volatile power profile, although the use of precious metal catalysts leads to higher costs.
In AEL electrolysis, an alkaline electrolyte is used, which reduces the required activity from the catalyst itself. A porous separator is used instead of a membrane, leading to higher cross-contamination. This contamination increases further during partial load operation, making it more challenging for AEL electrolysis to follow a volatile current profile. Additionally, entrained alkaline electrolyte can pass through the electrolyser and must be removed for subsequent processes. Here, the absence of precious metals results in lower investment costs.
Storage of hydrogen
Due to its low volumetric energy density, storing hydrogen under environmental conditions is not practical. The following basic methods are suitable for achieving sufficient energy density:
- Physical binding to a carrier material: This is done, for example, in solid metal hydride storage systems or in organic carrier liquids (LOHC).
- Liquefaction (LH2) by cooling below the boiling point (-252°C): This achieves a density of approximately 70 g/l.
- Pressure storage at different pressure levels: Depending on the pressure level, mass, and load cycle requirements, different types of tanks are used – from simple steel tanks to composite tanks.
- Chemical bonding in ammonia or hydrocarbons: Depending on the chemical compound, various other storage options are possible.
All methods have limitations in terms of their application. What almost all storage methods have in common is that the hydrogen must be compressed by compressor systems for the storage process.
Enjoyed what you've read so far? Read the full article and the rest of the Autumn 2025 issue of Energy Global here, or why not register today for free!
For more news and technical articles from the global renewable industry, read the latest issue of Energy Global magazine.
Energy Global's Autumn 2025 issue
Explore the latest insights into the renewable energy sector in the Autumn issue of Energy Global, out now! This edition features a regional report on the Asia Pacific from Aurora Energy Research, mapping out why the wholesale price cap is detrimental to the energy transition in India. The issue then delves into articles covering crucial topics such as digitalisation in renewables, inspection & maintenance, developments in floating offshore wind, coatings, solar optimisation and more. Contributors include Flotation Energy, DNV, Sarens, NEUMAN & ESSER, Teknos, and more, so this issue is not one to miss!