Frequently asked questions

The H2Nodes project aims to deploy innovative transport solutions providing public services to cities. Here is some additional information on the technology deployed.

How does a hydrogen fuel cell work?

A fuel cell is an electrochemical energy converter in which hydrogen and oxygen react, in a controlled manner and without combustion, to water, thereby generating power and heat. Pure water (H2O) is the by-product of this electrochemical reaction. Many fuel cells are lined up to form stacks when deployed in vehicles, in order to boost the electric current output.

How does a fuel cell electric bus work?

A fuel cell electric bus is an electric bus that includes both a hydrogen fuel cell and batteries/capacitors. In such hybrid architecture, the fuel cell provides all of the energy for the vehicle operation, whilst the batteries/capacitors are able to provide peak power to the motors to meet rapid acceleration and gradients. By using a fuel cell in conjunction with a battery, the size of each can be optimized for a given route. The fuel cell electric bus is an all-electric zero emission solution that offers an operation close to that of a diesel bus and hence is marketed as the closest like for like zero emission option to replace diesel.

How do the ‘HyTrolley’ trolleybuses work in Riga?

The ‘HyTrolley’ trolleybuses use hydrogen fuel cells as range extenders, as part of a new concept developed by Solaris Bus & Coach. The new solution enables operation of the trolleybuses on the sections of Riga public transport network without overhead wires. Each trolleybus is fitted with a fuel cell as well as a battery, allowing the vehicle to operate without traction energy supply for up to 100 km. This can be used to efficiently extend the city’s trolleybus network without the need to extend the overhead infrastructure.

How ‘green’ is hydrogen as a fuel?

Hydrogen can be produced from any form of primary energy, renewable or conventional. As a fuel it is widely available, efficient, renewable and non-polluting. Today, the majority of hydrogen is produced from steam reforming. However, an increasing number of plants are using renewable electricity to drive electrolysis which is totally renewable. Even when produced from fossil fuels, hydrogen can significantly reduce the overall amount of greenhouse gases and pollutants produced in power generation plants.

How is hydrogen produced?

Hydrogen can be produced through several different methods. The two main methods are:


Electrolysis is a process in which an electrolyser splits liquid water (H2O) into Hydrogen (H2) and Oxygen (O2) gases using electricity. An electric current splits water into its constituent parts. If renewable energy is used, the gas has a zero-carbon footprint, and is known as green hydrogen.

Steam Methane Reforming (SMR):

The primary ways in which natural gas, usually methane, is converted to hydrogen, through a reaction with steam. Pure water vapour is used as the oxidant. The reaction requires the introduction of heat and is therefore ‘endothermic’.

Is hydrogen safe?

Hydrogen has been used for a wide variety of industrial applications for more than 100 years. Hydrogen is abundant, non-toxic, colourless, odourless and tasteless, and is a clean, efficient and safe energy source. It is the lightest element in the world (even lighter than air), and if released into the atmosphere rises and dissipates quickly. This makes it safer than liquid fuels in an accident as it can be vented from the tank, leaving nothing to ignite.

Can fuel cell electric buses provide the same driving performance and experience as a conventional bus?

Fuel cell electric buses enable sufficient operational flexibility for demanding urban bus services, without limitations to quality and service. They offer the largest range of any zero-emission powertrain options (over 300km), with no need to return to the depot during daily service, and can refuel within 10 minutes. Bus performance is comparable to conventional buses in terms of speed and acceleration. Fuel cell electric buses also offer the same quiet, smooth and refined performance as battery electric buses. As with all electric vehicles maximum torque is delivered from zero rpm, which makes for very responsive performance when pulling away from standstill. Manufacturer development of the technology has ensured performance is maintained regardless of the local environment or climate.

What is an ‘Urban Node’

The H2Nodes project uses the concept of ‘Urban Nodes’. As such, pilot cities are considered as key nodes within the North Sea-Baltic Corridor TEN-T core network corridor. An ‘Urban Node’ is characterised by a city with high levels of connectivity within this corridor, where trans-European transport infrastructure (passenger terminals, airports, railway stations, logistics platforms, freight terminals) are connected to local infrastructure. Urban Nodes are key starting points for the development of integrated and intermodal clean transport across the transport network corridor in the future in Europe.

Can hydrogen transport ever become mainstream?

For hydrogen transport to become mainstream, the EU, Governments and industry must work in partnership to provide not only the financial resources but also the policy framework to achieve 'critical mass' and encourage adoption of this new and sustainable technology. As the network expands, economies of scale will drive costs down across the technology. As more refuelling facilities are installed, consumers will have the confidence that they will be able to refill their vehicles and so will start to purchase them.


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