Autobus wodorowy – innowacyjny element tkanki miejskiej.

One of the challenges facing public transport in modern cities is the transformation towards low carbon. The hydrogen bus is among the flagship vehicles of a sustainable evolution to improve air quality. However, the environmental credentials of this mode of transport do not exhaust the list of its advantages. Modern hydrogen buses are distinguished by their relatively short charging times and good range and are designed to operate efficiently and provide passengers with the most comfortable travel conditions possible. Inclusivity is also an important aspect considered in the development of hydrogen public transport. Manufacturers are working hard to ensure that their hydrogen buses are vehicles that are friendly to people with mobility disabilities, as well as the blind and visually impaired, among others.

Hydrogen-powered vehicles are one of the fastest growing areas in the public transport sector. This is influenced, among other things, by various subsidy programmes to support the implementation of clean public transport. In the remainder of this article, we will analyse, among other things, why there is so much interest in hydrogen buses, what their main advantages are, what their general principle of operation is, and what the current situation is regarding the use of this type of low-emission vehicles in Poland and around the world.

Hydrogen bus – one of the cornerstones of public transport of the future

Increasing the energy efficiency of vehicles and the use of renewable energy are currently among the strategic objectives of European transport and energy policy. The motivation for taking action in this direction is primarily the desire to prevent progressive climate change and an increase in air pollution. As road transport is a significant factor negatively affecting urban air quality, public transport has become one of the areas of particular focus in the development of new, greener technologies.

The process of modernising public transport and transforming it towards low-carbon modes of transport has become multifaceted over the years. An important part of the focus in recent decades has been on electromobility, understood mainly as BEVs (Battery Electric Vehicles), i.e. vehicles powered by electricity stored in rechargeable batteries. During this time – somewhat in the shadows, one might say – there has also been systematic progress in the use of hydrogen technology for propulsion in buses and trams. This has been fostered by various initiatives such as, among others, the international CHIC project, which aimed to support the market introduction of hydrogen fuel cell buses.

For some time now, we have also been able to observe the rise of public transport based on fuel cells in Poland. On the streets of larger and smaller cities in our country, it is increasingly common to see hydrogen buses running on a regular basis, attracting passengers with modern, ergonomic equipment and practical amenities such as free Wi-Fi or USB sockets for charging phones. The development of the situation in this area is evidenced by one of the indicators for achieving the goals set out in the Polish Hydrogen Strategy until 2030 with an outlook until 2040:

• 100 to 250 buses by 2025,
• 800 to 100 buses by 2030.

It is worth asking at this point why such high hopes are being pinned on hydrogen buses. The most important factor that determines the belief in the breakthrough nature of this type of vehicle is the many advantages of hydrogen as a fuel. What are the most important advantages of using hydrogen fuel cells to power city buses?

• Short full refuelling times – this is one of the key strengths of hydrogen buses and a very big advantage over strictly electric-based vehicles. A hydrogen bus (FCEV – Fuel Cell Electric Vehicle) takes on average around 15 minutes to refuel, while a battery bus (BEV) can require up to several hours to recharge (with plug-in chargers).
• Good range – advocates of hydrogen buses point to their high efficiency. Using hydrogen fuel cells, the bus may be able to cover up to 400 kilometres on a single fill-up.
• Low-emission – a very important issue in the context of the continuing interest in modern hydrogen-powered city buses is their environmental credentials. Assuming they use so-called green hydrogen (hydrogen produced by electrolysis of water using renewable energy), their operation does not involve CO2 emissions, making them zero-emission vehicles. However, even in the case of the use of so-called grey hydrogen (hydrogen produced by reforming natural gas or other hydrocarbons derived from oil refining), we can talk about the low-emission performance of the buses using it. In the course of the operation of hydrogen cells, besides electricity, only heat energy and water are produced.
• Safety – a properly designed hydrogen bus is a vehicle that is not only environmentally friendly and economical but also safe. This is due, among other things, to the properties of hydrogen itself, which is much lighter than air and has a high auto-ignition temperature in air of 585°C. This is significantly higher than, for example, petrol, which has an auto-ignition temperature of around 215°C. The lightness of hydrogen means that, in the event of a leak, it instantly becomes airborne, thus reducing the risk of ignition. The high auto-ignition temperature in the air, on the other hand, makes it difficult to initiate the combustion process of hydrogen with air without additional agents, which is important in terms of safety in the event of a collision.
• Low-temperature efficiency – hydrogen buses do not experience a drastic reduction in driving performance at lower temperatures.

There are also other reasons why more and more urban centres are choosing to invest in hydrogen buses. Worth mentioning in this context are:

• the low noise and vibration levels generated by this type of public transport,
• no load on the local power grid,
• various subsidy programmes to support the hydrogen transition of public transport in the area.

How does a modern hydrogen bus work?

Many people do not realise that hydrogen buses are essentially electric vehicles. They use hydrogen fuel cell kits to produce electricity. The by-products of this process are only heat energy and water. The electricity generated is channelled into the bus’s propulsion system and, in the case of many models of these vehicles, into a battery. The purpose of such a battery is to provide support to the hydrogen fuel cells when there is an increased energy requirement of the electric vehicle. Figuratively speaking, then, modern hydrogen buses are in fact electric vehicles with their own 'mini-electric power plants’ on the roofs.

What is the principle behind the hydrogen cells used in buses?

To better understand how a hydrogen bus works, it is worth discussing the operation of the hydrogen fuel cell, which is used to produce the electricity that powers the propulsion system of this modern vehicle. The hydrogen fuel cell consists of three basic components, which include:

• anode, or negative electrode,
• cathode, or positive electrode,
• proton exchange membrane separating the cathode and anode – often in the form of a polymer electrolyte.

The hydrogen fuel cell uses a reverse electrolysis reaction involving oxygen from the air and hydrogen supplied from tanks mounted on the bus. It allows electricity to be generated while the vehicle is in use, producing only heat and water vapour, which is removed to the outside. As a result, no harmful substances are produced. This allows the hydrogen bus to be called emission-free. The electricity produced goes to the vehicle’s propulsion system and to the battery that supports the cells in the event of higher energy demand.

What is the mechanism of the hydrogen bus?

How is a set of hydrogen cells able to power a modern bus? It is a multi-stage process that is worth analysing in detail.

1. The stage that initiates the whole process of energy flow in the vehicle is the supply of oxygen to the hydrogen cell in the form of air purified by special filters and hydrogen from tanks usually located on the roof of the vehicle. The hydrogen is transported to the anode, while the oxygen is transported to the cathode. Importantly, the surfaces of both electrodes are coated with a catalyst.
2. Hydrogen fed to the anode initiates a reaction with the catalyst. Its oxidation occurs, causing it to decay into electrons and protons in the form of hydrogen cations.
3. The proton exchange membrane only allows protons to pass through it, which pass to the cathode side, while it blocks the flow of electrons resulting from the decomposition of hydrogen.
4. Electrons from the oxidation of hydrogen are directed to the cathode by an external electrical circuit, creating a current that is used to drive the bus’ electric motor.
5. When the electrons are transported to the cathode, they bind to the oxygen there and are reduced to oxide anions.
6. Protons resulting from the oxidation of hydrogen pass to the cathode through the membrane, where they react with oxide anions to produce water and heat energy.

The electricity generated by the hydrogen fuel cell kit is supplied to the bus’s electric motor, as well as to the traction battery that acts as a booster. With the electricity produced, the vehicle can move. As a by-product of the cells’ operation, water and heat are removed to the outside.

Hydrogen buses in Poland – what is the current situation?

As a result of investments made in recent years, Poland is slowly becoming an increasingly important player in the European hydrogen bus market. The number of Polish cities served by carriers adding more hydrogen fuel cell buses to their fleets is increasing. Among the vehicles being tested and implemented in our country are hydrogen buses from foreign concerns such as Mercedes, for example, as well as from Polish companies. Crown examples of domestic hydrogen bus models include the NesoBus, produced at the newly established Świdnik plant, as well as the Solaris Urbino 12 Hydrogen.

The NesoBus brand was established as an initiative belonging to the Polsat Plus Group of companies and ZE PAK. The signature bus was designed from the ground up as a hydrogen construction powered by green hydrogen, which makes it an emission-free solution. It is characterised by, among other things:

• impressive range – up to 450 km,
• short refuelling time – up to 15 minutes,
• high efficiency – it can run without refuelling for up to 2 days; it consumes on average about 8 kg of hydrogen per 100 km and its tanks hold 37.5 kg of hydrogen,
• satisfactory capacity – accommodates up to 93 passengers, including up to 37 seated,
• the high quality of the hydrogen fuel cells used, sourced from the leading supplier of this type of solution, Ballard,
• the robustness of the hydrogen tanks – particularly important in terms of vehicle safety – supplied by the specialists in this field, Hexagon,
• an ergonomic, modular design, which allows components of the entire hydrogen system to be replaced in the future with other, better-performing components,
• construction based on the use of modern, lightweight materials and efficient air-conditioning and heating systems – contribute to a reduction in the need for electricity as well as fuel consumption in the form of hydrogen,
• modern design, which was the responsibility of Torino Design, a company with extensive experience of working with the automotive sector.

Also worth noting is the evocative name of the NesoBus, the first four letters of which are derived from the phrase: „No Exhaust Emissions, Cleanses (the air)”. It derives from the fact that this Polish hydrogen bus contributes to the elimination of emissions of harmful substances, including carbon dioxide, nitrogen oxides and particulates, in particular fine PM 2.5. Rybnik, for example, has already decided to implement NesoBuses in its public transport fleet, and in time it will also be possible to see them in Gdańsk or Chełm, for example.

In the field of industrial hydrogen bus design and production, Solaris Bus & Coach is also highly successful. This is borne out by data which shows that this manufacturer’s share of the European hydrogen bus market was as high as 44.5 % in 2023. Polish hydrogen buses Solaris Urbino 12 Hydrogen are an important element of public transport in more than 20 towns and cities located in various countries of the Old Continent, including, among others, the Netherlands, Italy, Germany, Austria or Sweden. In Poland, this model can be found, for example, on the streets of Konin or Poznań. On board the Solaris Urbino 12 Hydrogen, 85 passengers can travel in comfort and safety, including 37 in seating positions. 

It can be said with full conviction that the Polish hydrogen bus 'has more than one name’. Polish companies such as Autosan, Arthur Bus and Pilea, among others, are also involved in the production of this type of modern means of public transport. Local authorities are encouraged to invest in hydrogen-powered buses through various subsidy programmes, including, among others, Green Public Transport, operated by the National Fund for Environmental Protection and Water Management (NFOŚiGW). Other initiatives are also worth mentioning, such as the subsidies offered by the Centre for EU Transport Projects.

In doing so, it should be noted that for the development of public transport based on hydrogen cells, it is not only necessary to invest in the fleet but also in the appropriate infrastructure. This includes, among others:

• hydrogen filling stations – such places already exist, e.g. in Poznań, where near the Miłostowo tram terminus there is a publicly accessible 24/7 hydrogen filling station with three dispensers, set up by Orlen,
• plants for the production of green hydrogen, which would be able to meet the market demand for this element,
• transport infrastructure to ensure the efficient movement of hydrogen from the production site to the individual filling stations.

Harnessing the potential inherent in hydrogen buses requires systemic action and large financial outlays, but the benefits – both in the short and long term – make this the right direction for Poland to take.

Hydrogen buses – an important part of the modern urban fabric

Modern city buses using hydrogen fuel cells combine three aspects that can be summarised as '3 x E’:

• ecology,
• economics,
• ergonomics.

On the one hand, they are low- or – in the case of using green hydrogen – zero-emission electric vehicles whose only by-products are water and heat. On the other hand, they are characterised by good range, high efficiency and short charging times, making them financially viable in the long term. A third, and equally important, is the high level of comfort they provide for the passengers who move with them, including those with disabilities. It is therefore no surprise that an increasing number of Polish cities aspiring to be modern, climate-neutral and friendly to their inhabitants have innovative hydrogen buses on their streets.

Designing vehicles based on hydrogen technology, such as modern city buses equipped with hydrogen cell kits, for example, requires a very high level of interdisciplinary competence from the specialists involved. At Endego, we have many years of experience in leading and implementing technology projects in cooperation with bus manufacturing companies. As part of our comprehensive services, we provide active support at every stage of the respective project: from the development of the initial concept to the start of series production.

Are you planning the design of a modern green energy city bus and need the support of qualified engineers and designers to realise this ambitious project? Get in touch with us!

If you would like to learn more about the technology projects we have completed for bus manufacturers, we encourage you to read another article on our blog: Endego: A revolutionary approach in bus design.