Hydrogen hubs –what they are, how they work, and how they support public transport 

What is a hydrogen hub? 

Hydrogen hubs and hydrogen valleys are initiatives that create a complete value chain for hydrogen technologies – from green hydrogen production, through storage and distribution, to its use in transport and industry. In practice, this means integrating production, storage, and energy consumers, such as bus fleets.

Moreover, because hydrogen is an energy carrier, a hydrogen hub functions as a local energy system where renewable energy does not need to be used immediately after generation. It can be converted into hydrogen, stored, and used later.

Such a system can power hydrogen buses, charging infrastructure for electric buses, and local microgrids. A hydrogen hub can support heavy transport, rail, shipping, the chemical and steel industries, as well as district heating. It can supply energy to buildings or act as a flexible energy storage system within a city. In practice, a hydrogen hub operates as a large-scale urban energy storage system.

Not every hydrogen refuelling station is a hydrogen hub. A hub implies local production, storage, and integration with the energy system – not just fuel distribution.

Benefits for public transport 

Public transport is an ideal sector to integrate with such systems. Green hydrogen can be used daily in the regular operation of city buses. Energy from local renewable sources is directly supplied to public transport: vehicles are refuelled at night or during off-peak hours and operate routes during the day.

For residents, this translates into quiet, zero-emission buses, while operators gain access to a stable source of green energy.

Additionally, buses are not just transporting passengers – they can become part of an intelligent energy system. In the future, they may function as flexible energy storage, refuelling when renewable energy production is high and potentially feeding energy back when demand increases.

How does a hydrogen hub work? 

At the core of a hydrogen hub is an electrolyser, which produces hydrogen from water using electricity. The electrolyser consumes electrical energy and splits water into oxygen and hydrogen. During this process, the energy is not lost – it is stored within the hydrogen itself.

When hydrogen is later used in a fuel cell in a bus, the stored energy is converted back into electricity that powers the electric motor.

The hydrogen produced in the electrolyser is stored either in high-pressure tanks or in liquid form. Storing energy as hydrogen makes it possible to capture surplus energy generated by wind farms or solar panels and use it later.

On sunny or windy days, electricity production can exceed current demand. Power grids are not always able to absorb this excess, so some energy would otherwise be curtailed. An electrolyser allows this surplus to be utilised – converting excess renewable electricity into hydrogen that can be used later, for example during periods of low generation.

In practice, this means a bus can be powered by energy generated days or even weeks earlier from wind or solar sources. This is why hydrogen is considered a form of long-term energy storage – something that cannot be achieved with batteries alone at a city-wide scale.

European examples 

Hamburg – Moorburg Hydrogen Hub 
A classic example of a full-scale hydrogen hub. A ~100 MW electrolyser produces green hydrogen for the port and public transport, integrating industry and mobility. It demonstrates a “full” hub where hydrogen serves both as fuel and energy storage.

Bolzano – South Tyrol Hydrogen Valley 
A distributed energy and transport system where hydrogen powers urban and regional buses while storing surplus renewable energy. This is an example of a regional initiative supporting both transport and energy systems.

Frankfurt nad Menem (ICB) 
Public transport operator infrastructure where a fleet of hydrogen buses is supplied via a dedicated refuelling station. Hydrogen is mainly used for public transport, so it is not a full hydrogen hub, but it shows how transport can rely on local H₂ supply.

Cologne Region (RVK, North Rhine-Westphalia) 
A regional project combining hydrogen production and refuelling for public transport buses. Hydrogen is sourced mainly from industrial facilities and supplied to municipal fleets. This is an example of distributed infrastructure where public transport benefits from local hydrogen sources.

Public transport transformation is often discussed through the lens of vehicles – electric buses, trolleybuses, or hydrogen buses. However, the key shift is also happening in urban energy infrastructure. Hydrogen hubs can become a crucial element of the future mobility ecosystem.