The Concept of an Infrastructure Location to Supply Buses with Hydrogen: A Case Study of the West Pomeranian Voivodeship in Poland

Abstract

The growing energy crisis and increasing threat of climate change are driving the need to take action regarding the use of alternative fuels in transport, including public transport. Hydrogen is undoubtedly a fuel which is environmentally friendly and constitutes an alternative to fossil fuels. The wider deployment of hydrogen-powered vehicles involves the need to adapt infrastructure to support the operation of these vehicles. Such infrastructure includes refuelling stations for hydrogen-powered vehicles. The widespread use of hydrogen-powered vehicles is dependent on the development of a network of hydrogen refuelling stations. The aim of this article is to propose the conceptual location of infrastructure for fuelling public transport vehicles with hydrogen in selected cities of the West Pomeranian Voivodeship, in particular the cities of Szczecin and Koszalin. The methodology used to determine the number of refuelling stations is described, and the concept of the location for the refuelling stations has been proposed. Based on a set assumptions, it was stated that two stations may be located in the Voivodeship in 2025 and seven stations in 2040. The research results will be of interest to infrastructure developers, public transport companies, and municipalities involved in making decisions related to the purchase and operation of hydrogen-powered buses.

1. Introduction

Nowadays, a lot of attention is paid to the use of alternative fuels in the transport sector [1]. Among other reasons, this is due to the need to decarbonize transport, including public transport [2,3]. Green hydrogen is considered to be a solution for the future of the energy market [4,5] while providing fuel for transportation [6,7]. However, the introduction of hydrogen as a fuel needs specific infrastructure [8].

The establishment of infrastructure elements for fuelling public transport vehicles with hydrogen is crucial for the widespread adoption of hydrogen-powered vehicles, especially those used in public transport [9]. A robust hydrogen refuelling infrastructure is necessary to support the transition of public transport vehicles, such as buses, trains, and trams, to hydrogen fuel cells [10].

In the available studies, challenges impeding the large-scale utilization of fuel cell electric vehicles, including the high cost associated with platinum electrocatalysts and engineering constraints related to membrane, support, and catalyst stability, have been identified [11]. Moreover, the underdeveloped infrastructure needed for hydrogen-fuelled vehicles requires substantial investment and public confidence to become economically viable [11]. The feasibility of establishing a nationwide network of hydrogen refuelling infrastructure to facilitate the conversion of long-haul, heavy-duty truck fleets from diesel fuel to hydrogen has been explored [12]. Additionally, the integration of ejectors in hydrogen refuelling stations has been studied to streamline the introduction of hydrogen into the vehicle refuelling infrastructure [13]. The integration of hydrogen infrastructure for public transport vehicles is crucial not only for reducing emissions but also for enhancing energy management and planning in smart cities [14]. Furthermore, the development of fuelling protocols for gaseous hydrogen vehicles is essential to ensure the efficiency and safety of hydrogen mobility infrastructure [15].

In Poland, the Polish Hydrogen Strategy to 2030 with an outlook to 2040 was introduced [16]. It considers the implementation of hydrogen-powered buses in the transport sector and building refuelling stations for hydrogen-powered vehicles. However, the specific locations of these stations in the West Pomeranian Voivodeship in Poland have not yet been determined.

An analysis of the available literature revealed that the location issues affecting the infrastructure for hydrogen-powered buses, including refuelling stations in Poland, have been analysed only to a limited extent. Therefore, there is a need to investigate these issues and propose conceptual locations for refuelling stations for hydrogen-powered buses in the selected cities of the West Pomeranian Voivodeship in Poland.

The aim of the article is to propose conceptual location of infrastructure for the fuelling of public transport vehicles with hydrogen in selected cities of the West Pomeranian Voivodeship, in particular the cities of Szczecin and Koszalin. The preliminary research was carried out and the conceptual locations for refuelling stations were proposed, accounting for set assumptions for 2025 and 2040.

The present study was conducted in order to demonstrate an approach for determining possible locations of infrastructure for supplying buses with hydrogen in the West Pomeranian Voivodeship that may be used by decision-makers involved in the planning of infrastructure development for refuelling hydrogen-powered buses. The study fills in the research gap related to the determination of possible locations for hydrogen refuelling stations in the West Pomeranian Voivodeship in Poland.

The article includes a Literature Review section, where the available literature has been analysed. The Materials and Methods Section presents the general characteristics of the West Pomeranian Voivodeship, as well as detailing the methodology used to conduct the research. The concept of locating the refuelling stations for hydrogen-powered buses is shown in the Results section. A summary of the discussion was carried out and conclusions were developed in the Discussion and Conclusions sections.

2. Literature Review

A hydrogen refuelling station is a construction object that constitutes a functional and utility entity. Accordingly, its design, construction, release for operation, and operating rules are regulated by numerous normative acts on construction, technical, safety, or environmental aspects [17]. Infrastructure elements used for hydrogen fuelling include hydrogen generators (electrolysers), compression and storage systems, dispensers, and innovative technologies like ejectors [18,19]. These components are essential for establishing a comprehensive network of hydrogen refuelling stations to support the transition of various vehicles, including public transport vehicles, to hydrogen fuel cells [20]. Studies have also highlighted the importance of fast, precise, and secure metering of hydrogen for safe operation with hydrogen fuel. Additionally, the flexibility of hydraulic systems in adjusting valve opening duration and timing plays a significant role in hydrogen fuelling. Overall, the arrangement of infrastructure elements for hydrogen fuelling is a multifaceted process that involves addressing cost barriers, developing a comprehensive refuelling network, integrating innovative technologies, and establishing efficient fuelling protocols [21,22]. The transition to hydrogen-fuelled public transport vehicles can significantly contribute to developing sustainable and environmentally friendly transportation systems by overcoming these challenges and investing in the necessary infrastructure.

Integrating hydrogen-powered vehicles in public transport presents a promising solution for addressing environmental concerns and promoting sustainability. In the research conducted by Steenberghen and López [23] EU-funded projects like CUTE and ECTOS, which focus on testing the feasibility of hydrogen fuel cell-powered buses in urban public transport systems, indicating a growing interest in hydrogen as an alternative fuel, were discussed [23]. Ally and Pryor [24] highlighted the significance of hydrogen-fuelled vehicles in reducing greenhouse gas emissions, air pollutants, and dependence on imported energy, particularly in developing areas, emphasising the role of hydrogen technology in sustainable transportation solutions [24]. Moreover, Akac et al. [25] noted that public transport buses have been a primary area for testing hydrogen and fuel cell applications in road transport, suggesting buses as a key focus for implementing hydrogen-powered vehicles in public transport systems [25]. Additionally, Bao et al. [26] underscored the high energy density of hydrogen and its lack of greenhouse gas emissions during consumption, making it a suitable option for the transportation sector, emphasising the environmental benefits of hydrogen-powered vehicles in public transport [26]. The research supports the notion that hydrogen-powered vehicles have the potential to transform public transport by providing a clean and sustainable alternative to traditional fossil fuel-powered vehicles. However, infrastructure development, cost considerations, and public acceptance must be addressed to facilitate the widespread adoption of hydrogen technology in public transportation systems.

To successfully implement hydrogen-powered buses in public transport systems, several challenges and recommendations regarding infrastructure location for supplying buses with hydrogen must be considered. Firstly, the establishment of hydrogen refuelling stations is crucial. Liu et al. [27] discussed the installation of stations in Foshan to support over 1000 buses, emphasising the need for a sufficient number of refuelling stations to cater to a large fleet of hydrogen buses. Secondly, the strategic placement of charging infrastructure is essential. Xylia et al. [28] highlighted the importance of locating charging infrastructure for electric buses to balance fuel costs and emissions reduction, suggesting similar considerations apply to hydrogen infrastructure placement. Furthermore, Kunith et al. [29] emphasised the need for a comprehensive infrastructure plan to equip bus routes with charging stations, indicating that careful planning and optimisation are necessary for cost-effective charging infrastructure placement for hydrogen buses. The charging may occur at terminal stops, depots, bus stops and other places. It should be noted that different users’ needs may impact the selection of the charging stations′ location (

Table 1. Different users’ needs that may impact the selection of charging stations (own elaboration based on [30,31,32]).

Users Type	Selected Station Location Preferences
Bus operators	Costs, bus lines congestion, accessibility, strategic location, energy storage systems, infrastructure compatibility, station power and charge efficiency, safety of performed operations, etc.
Individual/residential users	Prices, location, accessibility, convenience, and charging point information and payment system, charging station level of service, charging power, comfort and amenities, etc.

).

Moreover, the location of hydrogen infrastructure is impacted by legal factors [33]. Wang et al. [34] suggested that policymakers should focus on strengthening publicity efforts to increase environmental awareness among individuals and optimise the layout of hydrogen-fuelled bus schedules to enhance the riding experience and promote the adoption of hydrogen buses. The challenges related to infrastructure location for supplying buses with hydrogen include the determination of the need for an adequate number of refuelling stations, the strategic placement of charging infrastructure, comprehensive infrastructure planning, and public awareness initiatives. The advantages of hydrogen fuel cell electric vehicles (FCEVs) compared to battery electric vehicles (BEVs) in terms of infrastructure used are shown in

Table 2. The advantages of hydrogen fuel cell electric vehicles compared to battery electric vehicles in terms of infrastructure used (own elaboration based on [35,36,37]).

Type of Vehicle	Advantages	Infrastructure Implication
FCEVs	Fast refuelling: FCEVs can be refuelled with high-pressure hydrogen gas in several minutes	Hydrogen refuelling stations can potentially service many vehicles per dispenser per day
	More extended range: FCEVs typically offer ranges of 300–400 km and more	Fewer stations are needed overall to provide coverage, especially on long-distance corridors, compared to shorter-range BEVs
	Lower weight sensitivity: hydrogen tanks weigh significantly less than the massive batteries required to give heavy-duty trucks or buses	Infrastructure planning can focus strategically on freight corridors, ports, and distribution hubs, where the value proposition is strongest
	Reduced network load at the dispensing point: FCEV does not draw massive instantaneous power from the grid like multiple DC fast chargers operating simultaneously	Planning of station locations focus on the hydrogen supply chain (production, transport, storage) rather than solely on high-power grid upgrades at every station location
	Scalable station capacity	Adding more storage and dispensers can potentially scale the vehicle throughput of a hydrogen station more easily than adding multiple Megawatt-level chargers
BEVs	Use of the existing electrical grid, which already exists	Upgraded or existing grid capacity may be used for installing charging stations, not building an entirely new fuel production, transportation, and distribution network
	Different charging options: BEVs can be charged at home overnight, at various public locations or at other places	Infrastructure planning can include incentives and standards for home/work charging (slow or fast), distributing the load and cost
	Energy-efficient charging: using electricity directly from the grid to charge a battery is generally more energy-efficient than using electricity to produce hydrogen	The infrastructure must support a lower total energy demand for the same number of kilometres travelled
	Lower station complexity and cost: slower/fast chargers may be installed in different locations	Chargers are generally less complex and expensive per unit than high-pressure hydrogen refuelling stations currently
	Market adoption: BEVs have a significant head start in market adoption	There is an established demand to justify investment

.

To optimise the number and placement of charging stations for public transport, various methodologies have been proposed in the literature. Eisel et al. [38] discussed a game-theoretic approach to optimise the allocation of public charging stations, considering factors such as route choices and electricity prices to maximize social welfare. Luke et al. [39] emphasised the joint optimisation of autonomous electric vehicle fleet operations and charging station siting to ensure optimal coverage. Clairand et al. [40] and Liu and Wang [41] focused on coordinated siting and sizing of charging stations for electric vehicles, considering traffic conditions and power system interactions. Betancourt-Torcat et al. [42] highlighted the significance of multi-period power infrastructure and charging station network planning models, which consider vehicle movement and driving patterns to determine suitable locations for charging stations over time. Sharma [43] and Golla et al. [44] proposed using meta-heuristic techniques and optimisation technologies to determine the optimal number and locations of charging stations, considering factors such as charging speed, capacity, and energy management. These approaches aid in efficiently planning the infrastructure needed to support hydrogen-powered public transport systems. By considering traffic patterns [45,46], power system interactions [47], and optimization technologies, stakeholders can make informed decisions regarding the number and locations of charging stations to facilitate the widespread adoption of hydrogen-powered public transport.

Various strategies can be implemented based on the available literature to improve the infrastructure for fuelling public transport vehicles with hydrogen in cities. Ingvardson and Jensen [48] emphasised the importance of efficient boarding and alighting processes, and holding strategies to minimise vehicle bunching, thereby improving the reliability of public transport operations. Quan et al. [49] paid attention to the safety and reliability of fuel cell vehicles’ operation, proposing a remote monitoring system based on 5th generation (5G) mobile networks and controller area networks. Ghaffar and Aziz [50] recommended incorporating green infrastructure, mixed land uses, and improved accessibility to public transportation to enhance economic sustainability in housing projects, which can be extended to hydrogen infrastructure planning. Siekmann and Sujan [51] introduced the OR-AGENT tool for optimising long-term hydrogen refuelling infrastructure plans, emphasising the strategic deployment on freight corridors for heavy-duty FCEVs. Additionally, Butturi and Gamberini [52] discussed the potential of hydrogen technologies for low-carbon mobility, underlining the importance of sustainability and urban-industrial symbiosis in infrastructure planning. Moreover, Creutzig et al. [53] stressed the significance of economic and technical solutions, such as inner-city tolls and public transport infrastructures, coupled with city design considerations for enhancing public spaces, green space access, and connectivity for walking and cycling. Kariuki and Kuria [54] suggested promoting sustainable transport modes like public transport and investing in city structures to reduce private vehicle usage. However, it was also noted that in many situations, buses, long-haul freighters, and military vehicles, can all run predetermined routes out of a central hub, and whole fleets can be refuelled from a single location [55].

The European Union has strategically integrated hydrogen refuelling stations into its broader agenda of achieving sustainable transportation and decarbonization targets. By facilitating the adoption of FCEVs, which produce only water vapour as emissions, hydrogen refuelling stations significantly contribute to reducing greenhouse gas emissions in alignment with the EU’s climate objectives. Furthermore, these stations support the integration of renewable energy sources, as hydrogen can be produced through electrolysis powered by renewable energy, thus enhancing the EU’s energy transition efforts. The development of hydrogen infrastructure is encouraged by EU directives such as the Alternative Fuels Infrastructure Directive [56], which promotes sustainable and alternative fuels across member states. The implementation of hydrogen-powered buses is also conditioned by the commitments of the “Paris Agreement” [57] or the “Fit for 55” [58] package. Moreover, in the Polish Act on amending the Act on electromobility and alternative fuels and certain other acts [59], it is stated that municipalities with more than 100,000 inhabitants will only acquire zero-emission buses for passenger transport in that municipality. Smaller municipalities with between 50,000 and 100,000 inhabitants will also be obliged to use low- and zero-emission buses in public transport. The selected parameters of FCEVs are shown in

Table 3. Selected parameters of FCEVs and exemplary values (own elaboration based on [60,61,62,63,64]).

Parameter	Description	Value Range
Hydrogen storage capacity	Amount of hydrogen stored in onboard tanks	37.5 kg (5 rooftop tanks, Type IV)
Range	Maximum driving distance on a full hydrogen tank	Up to 350 km (Solaris Urbino 12) ~300 km (NesoBus)
Refuelling Time	Time required to refuel the hydrogen tanks to full	Approximately 8–15 min
Efficiency	The efficiency of converting hydrogen energy into electricity	Around 45–60%
Electric Motor Power	Power output of the electric traction motor	160–180 kW
Battery Capacity	Capacity of the onboard battery used for boosting and regenerative braking	30–60 kWh (Li-ion battery)
Top Speed	Maximum achievable speed	Around 85 km/h
Acceleration	Time to reach operational speed (e.g., 0–50 km/h)	~20 s

. The selected parameters of buses produced by Solaris and Nesobus companies located in Poland are presented in

Table 4. Selected parameters of buses produced by Solaris and Nesobus companies (own elaboration based on [64,65,66]).

Parameter	Solaris Urbino 12 Hydrogen	Solaris Urbino 18 Hydrogen	Nesobus
Drive axle	Electric axle with two integrated motors 2 × 125 kW	Portal axle Central engine standard	Model AVE 130 AxTrax
Hydrogen fuel cell, kW	70	100	70
Hydrogen tank type	Type 4, composite tanks	Composite tanks	Type 4, composite tanks
Hydrogen tank capacity, l	1560 (5 × 312)	5 × 312, 3 × 190	5 × 312
Batteries, kWh	Solaris High Power, 29.2	Solaris batteries, about 60	Type LTO, 2 × 15.2

.

Additionally, hydrogen’s ability to store excess renewable energy and balance the grid is crucial for increasing renewable energy shares and ensuring energy reliability. Particularly effective in decarbonising heavy transport sectors like buses, trucks, and trains, hydrogen addresses energy density requirements that are challenging for battery technologies. Supported by EU initiatives like the European Green Deal and Horizon Europe, hydrogen technologies are expected to play a central role in transforming the transport sector and achieving long-term climate neutrality [58].

In Poland, the activities supporting the implementation of hydrogen-powered buses are mentioned in the Polish Hydrogen Strategy to 2030 with an outlook to 2040 [16]. This strategy identifies the start of operation of 100 to 250 new hydrogen-powered zero-emission buses by 2025. Furthermore, by 2030, the strategy anticipates the beginning of operation of 800 to 1000 new hydrogen-powered buses, including those manufactured in Poland. Moreover, the strategy indicates a projected demand for hydrogen in the transport sector in Poland, expected to be around 2933.5 tons, including as much as 1764 tons for refuelling zero-emission buses. It is assumed that a minimum of 32 hydrogen refuelling stations, operating at 350 and 700 bar, will be constructed by 2025 to meet such demand. However, implementing hydrogen-powered buses in public transport in Poland faces numerous challenges that impact the decisions made by transport company managers [22]. The main concerns include i.a. the limited access to refuelling stations and constrained access to hydrogen.

In Poland, hydrogen-powered buses have already been introduced in Poznań, Gdańsk, Rybnik, Konin, and Chełm, among others [67]. As of the end of April 2025, Poland’s electric bus fleet consisted of 1450 units, while the hydrogen-fuelled bus fleet comprised 93 [68]. It is anticipated that the number of registered hydrogen-fuelled buses will increase [67].

Based on the analysis of available literature, it can be stated that the issues related to the conceptual location of refuelling stations, particularly in specific voivodeships of Poland, should be examined in greater detail.

3. Materials and Methods

3.1. Characteristics of West Pomeranian Voivodship in Poland

West Pomeranian voivodeship (Figure 1) is one of 16 voivodeships in Poland. It is located in the northwestern part of Poland and comprises 18 powiats, 3 cities with powiat status, 113 total gminas, 66 cities and towns [69]. It is the fifth largest region in the country, with an area of 22,907 km² and the eleventh largest in terms of population (population in 2023 was 1,631,784 inhabitants) [69]. The capital of the voivodeship is Szczecin (Figure 2).

The West Pomeranian Voivodeship is located at the intersection of international transport routes and has convenient access to the network of European motorways and expressways. The main roads connecting the West Pomeranian Voivodeship with neighbouring areas are expressways, including the S3, S6, S10, the S11, as well as the A6 motorway. It should be noted that this motorway is a continuation of the German A11 motorway and, together with it, forms a connection between Szczecin and Berlin via the international road route E28 [71].

According to data from the Statistical Office in Szczecin [72], in 2023 in the West Pomeranian Voivodeship of Poland, the length of regular bus transport lines decreased. Buses carried passengers on 646 domestic routes with a length of 28,500 km (in 2022–29,200 km) and 3 international routes with a length of 439 km. The number of buses operated by road transport operators in 2023 was 11.3% higher than in the previous year, amounting to 845 units. The bus fleet in domestic transport carried 17.4 million passengers in 2023, 16.6% more than previous year. Transport operations increased by 7.3% and amounted to 581.9 million passenger-kilometres. The average transport distance of 1 passenger was 33 km, 3 km shorter than in 2022.

The present study focuses on two cities of the West Pomeranian Voivodeship: Szczecin and Koszalin. Both cities have powiat status. Selected data on the area, population, and population density of the studied cities are shown in

Table 5. Selected data on cities of Szczecin and Koszalin (own elaboration based on [73]).

City with Powiat Status	Area, km2	Population (30 June 2024), Thousand Persons	Population Density, Persons/km2
Szczecin	300.55	387.7	1290
Koszalin	98.34	105.1	1069

[73].

Szczecin and Koszalin were selected to propose the conceptual location of the infrastructure for hydrogen-powered vehicles. These cities have a well-developed road infrastructure network and public transport that carries passengers using conventional and electric vehicles. Roads of national and regional importance pass through both cities. Currently, these cities have no hydrogen refuelling stations for public transport vehicles.

3.2. Methodology Used to Conduct the Research

The methodology used to conduct the research included the steps presented in Figure 3. Based on the literature review, the scope of data needed to present the study was identified, including the public infrastructure network, traffic intensity, public transport stops locations, etc. The appropriate databases had been created. The traffic intensity in the cities was analysed. Based on data provided in the Polish Hydrogen Strategy until 2030 with an outlook to 2040 [16], the number of hydrogen refuelling stations for the West Pomeranian Voivodeship was calculated. Considering calculated number of stations and created databases, the locations of hydrogen refuelling stations in selected cities were proposed.

The following assumptions were set to conduct the research:

1.

Solaris Urbino 18 hydrogen FCEVs produced in Poland will be operated (Table 4). Green hydrogen will be used for fuelling operations.

2.

The stations will be located in the two biggest cities of West Pomeranian Voivodeship: Szczecin and Koszalin. These cities were chosen considering their size (over 100,000 inhabitants) and importance in the voivodeship. Szczecin is the capital and the largest city in the voivodeship. Koszalin takes second place in terms of the number of inhabitants in the analysed voivodeship [74,75].

3.

The stations could be located near areas with heavy traffic. It was assumed that they would be used by hydrogen-powered buses and passenger cars.

4.

The calculations will be based on data available in the Polish Hydrogen Strategy until 2030 with an outlook to 2040 [16], as well as data provided by the Central Statistical Office in Poland [76].

5.

The number of hydrogen refuelling stations will be calculated for 2025 and 2040.

6.

The location of stationary stations for fuelling vehicles with hydrogen will be proposed. Each station should include the following elements: dispenser, compressor, and stationary tanks. One station may include several dispensers.

To conduct calculations, the following approach was applied: the number of buses registered in the country and analysed region was used to determine the number of stations that may be placed in the voivodeship. The number of registered buses was considered because the hydrogen-powered buses may be introduced within existing bus connections. It should be noted that different public transport vehicles (e.g., trams, high-speed rail, metro, etc.) may be used in particular regions.

The percentage of buses registered in the West Pomeranian Voivodeship against buses registered in the country ($Pbr$) can be calculated using Equation (1):

$$Pbr={\displaystyle \frac{Zbrv}{Zbrc}}\ast 100 [\%],$$

(1)

where

• $Zbrv$—registered buses in the West Pomeranian Voivodeship, pcs.,
• $Zbrc$—registered buses in Poland, pcs.

To calculate the assumed number of stations by 2025 and 2040 for the West Pomeranian Voivodeship, Equation (2) can be applied:

$$Lstv=Lsp\ast Pbr [\mathrm{pcs}.],$$

(2)

where

• Lstv—number of hydrogen refuelling stations per voivodeship, pcs.,
• Lsp—number of stations planned for analysed time period, pcs.

The Equation (3) was used to calculate the number of stations planned to be placed in particular cities (Lstc):

$$Lstc={\displaystyle \frac{(Lstv\ast Pbrc)}{100\%}} [pcs.],$$

(3)

where

• Pbrc—percentage share of buses registered in a particular city against the number of buses registered in the analysed cities, pcs.

To select the location of hydrogen refuelling stations, traffic intensity in the cities of Szczecin and Koszalin was analysed. Figure 4 and Figure 5 show the traffic intensity on individual road sections at 06:00 AM, 12:00 PM, 4:00 PM and 8:00 PM in Szczecin and Koszalin.

While analysing data presented in Figure 4, it can be stated that the traffic intensity in Szczecin at 06:00 AM on each road section is similar and indicates that the estimated passage of vehicles is smooth (green colour). At 12:00, there is a noticeable increase in traffic volume on some sections, as Długi Bridge in Szczecinie, 3 Maja Str., Bolesława Krzywoustego Str., Ku Słońcu Str., 26 Kwietnia Str., Piastów Ave. and other roads. The main road sections with the highest traffic intensity between 12:00 PM and 4:00 PM (marked in yellow/red) are located in the area of the city centre, Łasztownia, Turzyn, etc. After 16:00, traffic intensity on roads in Szczecin decreases.

In Koszalin, however, the traffic intensity is increasing (colour yellow and red) after 8:00 AM, with the highest peak occurring at approximately 4:00 PM, then it is gradually decreasing (Figure 5). Road sections with increased traffic during rush hours are located mainly at Lechnicka Str., Młyńska Str., Zwycięstwa Str. and other.

According to the Polish Hydrogen Strategy until 2030, with an outlook to 2040, the number of hydrogen stations in Poland should be at least 32 in 2025 [16]. It can be assumed that this number may be increased to 150 stations in 2040. These numbers were considered when determining the number of stations to be located in Szczecin and Koszalin.

The calculation of the amount of hydrogen $A_{H2}$ needed for daily buses refuelling will be based on the set assumptions and will be performed using Equation (4):

$$A_{H2}=N_b\ast M\ast CR \left[\mathrm{kg}\right],$$

(4)

where

• $N_b$—number of buses planned for Szczecin and Koszalin (per phase: 2025, 2030, 2040), pcs.,
• $M$—estimated average daily mileage per bus (can be based, e.g., on data from public transport operators), km,
• $CR$—average hydrogen consumption rate for typical hydrogen buses, kg H₂/100 km.

Based on the achieved amount of hydrogen (which can be considered as demand for hydrogen), it is possible to determine the station capacity. Let us calculate required dispensing rate using Equation (5):

$$R_d=D_{H2}/T [\mathrm{kg}/\mathrm{hour}],$$

(5)

where

• $R_d$—required dispensing rate, kg/hour,
• $D_{H2}$—total daily demand for hydrogen, kg (${D_{H2}=A}_{H2}$),
• $T$—available refuelling window, hours.

Adjusting for target utilisation rate, it is possible to assess the corrected dispensing rate required ($R_{dc}$) using Equation (6):

$$R_{dc}=R_d/R [\mathrm{kg}/\mathrm{hour}],$$

(6)

where

• $R$—target utilization rate, %.

The number of required dispensers ($N_d$) can be calculated as follows (Equation (7)):

$$N_d=R_{dc}/RR [\mathrm{pcs}.],$$

(7)

where

• $R_{dc}$—required corrected dispensing rate, kg/hour,
• $RR$—refuelling rate per one dispenser, kg/hour.

This allows to estimate the required on-site hydrogen storage capacity for the set number of days to ensure buses refuelling.

4. Results

4.1. Calculation of the Number of Hydrogen Refuelling Stations for the West Pomeranian Voivodeship

Calculations of the number of hydrogen refuelling stations for the West Pomeranian Voivodeship were performed using data from the Central Statistical Office [76], which includes the number of registered buses in the country.

A total of 132,353 buses were registered in Poland in 2023, including 6517 of such vehicles in the West Pomeranian Voivodeship [76]. This means that the share of buses in the West Pomeranian Voivodeship is approximately 5% of the total number of buses registered in the country.

The number of hydrogen refuelling stations for the West Pomeranian Voivodeship (Lstv) for the selected years was calculated as follows (Equations (8) and (9)):

• For 2025:

$$Lstv=32\ast 5\%\approx 2 pcs.,$$

(8)

• For 2040:

$$Lstv=150\ast 5\%\approx 7 pcs.$$

(9)

Considering that two hydrogen refuelling stations may be built by 2025 in the West Pomeranian Voivodeship, it was assumed that one station would be located in Szczecin and 1 station would be placed in Koszalin.

To determine the number of hydrogen refuelling stations that could be located by 2040 in particular cities (Szczecin and Koszalin), current data from the Central Statistical Office in Poland [76] were explored. These data indicate the number of buses registered in both cities. Considering that the total number of planned stations is seven, the numbers of already registered buses in Szczecin and Koszalin were analysed and compared.

According to statistical data from 2023 [76], the number of registered buses in Szczecin (1718 buses) and Koszalin (435 buses) amounted to a total of 2153 vehicles. Based on these data, it was possible to determine the percentage share of buses registered in a particular city against the number of buses registered in the analysed cities—in Szczecin (79.8%) and in Koszalin (20.2%). The calculated number of stations to be located in selected cities by 2025 and 2040 is presented in

Table 6. Calculated number of hydrogen refuelling stations in Szczecin and Koszalin [own elaboration].

City with Powiat Status	Percentage Share of Buses Registered, %	Calculated Number of Stations, pcs.
		2025	2040
Szczecin	79.8	1	6
Koszalin	20.2	1	1
Sum	100	2	7

.

Using Equation (3), the number of hydrogen refuelling stations in 2040 was calculated for Szczecin—six stations, and for Koszalin—one station. It should be noted that these calculation results are obtained based on the assumptions mentioned above.

4.2. The Concept of Hydrogen Refuelling Stations Location in Szczecin

Szczecin is a highly developed city with many green areas, such as the largest park in the city—Kasprowicz Park, with an area of about 50 ha [78]. There are many historic places under legal protection, universities, schools, kindergartens, shopping centres and other infrastructure elements necessary for the city functioning. Szczecin includes four districts: Śródmieście, Północ, Zachód and Prawobrzeże. Public transport in Szczecin is well developed and is administered by the Roads and Public Transport Authority. The public transport network includes buses and trams lines. There are over 60 daytime bus lines and 16 night bus lines [79]. Figure 6 shows a fragment of the bus lines network in Szczecin.

In 2024 there were no stations for fuelling vehicles with hydrogen in Szczecin. According to the results of the presented calculations, the number of hydrogen refuelling stations for the city of Szczecin will be one by 2025, and 6 by 2040. Figure 7 shows the proposal of one hydrogen refuelling station location in the city of Szczecin.

A proposal for the location of station for fuelling buses with hydrogen in Szczecin (Figure 7) considers the above-mentioned assumptions, including the results of a traffic intensity analysis. The station’s location is proposed in the place where the gas station is currently located. Deploying it in the proposed area may have several benefits, such as easy access to the station, the process of future operation of this hydrogen station may be facilitated considering the developed road transport infrastructure. Moreover, the location of stationary hydrogen station is proposed in the populated district of Szczecin city (Śródmieście). It should be emphasized that in accordance with the assumptions of the Polish Hydrogen Strategy to 2030 with an outlook to 2040 [16], the first hydrogen refuelling stations are suggested to be located in agglomerations and densely populated areas for refuelling primarily buses and railroads. The Śródmieście district includes ten housing estates and the number of inhabitants is 105,800 (31 December 2023) [81].

For the 2040, the location of six hydrogen refuelling stations in Szczecin is shown in Figure 8. The selection of proposed locations was based on data on the number of inhabitants in four districts of the city of Szczecin, as well as traffic intensity analysis.

Equation (10) was used to calculate the number of stations that should be located in a given district ($Lstcd$) of Szczecin:

$$Lstcd={\displaystyle \frac{Pd\ast Lstc}{100\%}} [pcs.]$$

(10)

where

• $Pd$—percentage share of the population of a selected district of Szczecin in relation to population of the entire city, %,
• $Lstc$—number of planned stations in the city, pcs.

Applying Equation (10), the number of stations was calculated for particular districts of Szczecin.

Table 7. Proposed number of hydrogen refuelling stations for individual districts of Szczecin (own elaboration based on [81]).

District	Number of Settlements, pcs.	Population of Each District (31 December 2023), Persons	Percentage Share of Population of Each District, %	Calculated Number of Stations, pcs.
Śródmieście	10	105,800	30	2
Północ	7	637	16	1
Zachód	9	112,602	32	2
Prawobrzeże	11	76,860	22	1

shows the results of these calculations.

Table 8. Proposed location of the six hydrogen bus refuelling stations in Szczecin (own elaboration based on [77,79]).

No.	Station Location		Order of Station Implementation	Comment
	Street/Avenue	District
1	Adama Mickiewicza Str.	Śródmieście	1	The station may be located near a section of the public transport network, which includes lines such as 60, 67, 86.
2	Wojska Polskiego Ave.	Zachód	2	The station may be located near a section of the public transport network, which includes lines such as 53, 60.
3	1 Maja Str.	Śródmieście	3	The station may be located near a section of the public transport network, which includes lines such as 53, 58, 60, 63.
4	Profesora Ludwika Janiszewskiego Str.	Zachód	4	The station may be located near a section of the public transport network, which includes lines such as 53, 61.
5	Goleniowska Str.	Prawobrzeże	5	The station may be located near a section of the public transport network, which includes lines such as 64, 96, C.
6	Bogumińska Str.	Północ	6	The station may be located near a section of the public transport network, which includes lines such as 101, 107, 63.

presents proposals for the exact locations of hydrogen refuelling stations and the suggested order in which each station should be implemented.

The suggested sequence of implementing hydrogen refuelling stations for buses in Szczecin was determined considering the population density in each of the four districts of Szczecin and access to public transport, i.e., available bus lines operating within these locations.

4.3. The Concept of Hydrogen Refuelling Station Location in Koszalin

In terms of size, Koszalin ranks as the second city in the West Pomeranian Voivodeship. The city is characterized by a large share of green areas, which cover over 40% of the entire city area, including the historic Pomeranian Dukes Park [82]. It is also a medium-sized city in terms of industry, with the electromechanical industry having an advantage. There are many commercial facilities in Koszalin, including shopping centres, department stores and other urban infrastructure elements. Public transport in Koszalin includes twelve city bus lines [83]. In 2024, there were no stations for fuelling vehicles with hydrogen in Koszalin. Figure 9 shows the city’s public transport network.

The proposed number of stations in Koszalin for 2025 and 2040 is identical. In accordance with the calculations presented above, the number of proposed stations is one. The proposal of the location of hydrogen refuelling stations for buses in Koszalin is presented in Figure 10.

A station for fuelling buses with hydrogen in Koszalin is proposed to be located near the Municipal Transport Company in Koszalin, because this place is crucial for the city in terms of public transport vehicles service. Several public transport lines run near the proposed station, including lines 4, 8, 16. Additionally, the location of station is close to frequently used roads, which may affect the use of a given station by users of other types of vehicles.

4.4. Calculation of Hydrogen Amount Needed for Buses Operation

Let’s assume the following:

1.

The number of hydrogen-powered buses ($N_b$) planned for 2025, 2030, 2040 is as follows:

• Szczecin city:

  -

  2025: 10 buses,

  -

  2030: 20 buses,

  -

  2040: 30 buses,

• Koszalin city:

  -

  2025: 5 buses,

  -

  2030: 10 buses,

  -

  2040: 15 buses.

2.

Estimated average daily mileage per bus ($M$): 200 km/day.

3.

Average hydrogen consumption rate for a typical hydrogen- powered bus ($CR$): 8 kg H₂/100 km.

The calculation results are presented in

Table 9. Estimated daily hydrogen demand, kg [own elaboration].

City with Powiat Status	2025	2030	2040
Szczecin	160	320	480
Koszalin	80	160	240

. It can be noted that the daily hydrogen demand in 2025 for Szczecin is 160 kg, considering that 10 buses are operated with an average daily mileage of 200 km. For Koszalin, this demand will be 80 kg/day in 2025 (based on introduced assumptions).

Using these results, it is possible to determine the station size and the number of needed dispensers. Let us assume that the following:

1.

The estimated daily hydrogen demand ($D_{H2}$) for 2040 is used.

2.

Typical refuelling time per bus refuelling: 15 min.

3.

Available refuelling window ($T$): 10 h (600 min) of refuelling time.

4.

Target utilization rate for dispensers: 70% utilization rate for dispensers.

5.

Refuelling rate per one dispenser ($RR$): 30 kg/hour.

6.

Hydrogen should be stored within the station to cover 1–3 days demand.

Calculation results are presented in

Table 10. Estimated hydrogen storage capacity for 2040, pcs. [own elaboration].

City with Powiat Status	Daily Demand, kg/day	Dispensing Rate Required, kg/hour	Number of Dispensers, pcs.	Days of Storage, Number of Days	Hydrogen Storage Capacity, kg
Szczecin	480	69	3	1	480
				2	960
				3	1440
Koszalin	240	34	2	1	240
				2	480
				3	720

.

Achieved results analysis revealed that for Szczecin city, the hydrogen storage capacity for three days will be 1440 kg, considering demand estimated under the set assumptions for 2040. In turn, for Koszalin city this capacity was estimated to be 720 kg.

5. Discussion

The number of hydrogen refuelling stations that could be located in two selected cities of the West Pomeranian Voivodeship, i.e., Szczecin and Koszalin, was calculated. The location of these stations was proposed, taking into account the forecast for 2025 and 2040. Based on calculations carried out for specific assumptions, it was found that two hydrogen refuelling stations could be built in the West Pomeranian Voivodeship by 2025: one station could be located in Szczecin, and the second one in Koszalin. By 2040, seven stations could be placed in the voivodeship, of which six were proposed to be located in Szczecin.

The selection of the number of stations for given cities was based on the Polish Hydrogen Strategy until 2030 with an outlook until 2040 [16] and the adopted assumptions that may impact the research results. Assuming that the strategy mentioned above indicates that the first hydrogen refuelling stations in the country should be located in densely populated places, specific locations where these stations could be built have been identified. When selecting the locations, the course of public transport routes in both selected cities, as well as traffic intensity, were considered. It should be noted that the obtained calculation results were primarily influenced by the adopted assumptions [16]. The number of hydrogen-powered buses in operation in the analysed cities, the location of stations and the demand for hydrogen may be different, which may be influenced by technical, technological, legal and economic factors.

The article presents preliminary study with a rather simple methodology. The developed approach to determine the number of stations in analysed region considers the number of registered bused in country and in the West Pomeranian Voivodeship. This approach was taken, because in regions different transport modes for public transport (e.g., trams, high-speed rail, metro, etc.) may be used; therefore, the bus traffic had to be addressed. Presented approach may be developed in future. Another way to determine the number of refuelling stations for the voivodeship may be based, e.g., on the number of citizens in particular regions.

The number of six refuelling stations for Szczecin city for 2040 may be discussed. This number comes from the assumption that only two cities in the West Pomeranian Voivodeship were considered. Moreover, it should be noted that the total number of buses in the cities analysed in the study represents only 33% (2153) of the buses registered in the voivodeship. Assuming that other cities of West Pomeranian Voivodeship will consider the introduction of hydrogen-powered buses in 2040 for urban transport or intercity connections within analysed region (

Table 11. Selected data on cities and towns in the West Pomeranian Voivodeship for the location of stations for fuelling hydrogen-powered buses in 2040 [own elaboration based on [73,76]].

Selected Cities and Towns	Area, km2	Population (30 June 2024), Thousand Persons	Registered Buses (2023), pcs.	Proposed Number of Stations, pcs.
Szczecin	300.55	387.7	1.718	3
Koszalin	98.34	105.1	1.443	1
Stargard	48.08	66.272	528	1
Kołobrzeg	25.67	43.364	26	1
Świnoujście	197.20	38.728	138	1

), the location of stations may present as is shown in Figure 11.

The conceptual location of stations for fuelling hydrogen-powered buses in Świnoujście, Kołobrzeg and Stargard is presented in

Table 12. Conceptual locations of stations for fuelling hydrogen-powered buses in selected cities (own elaboration based on [77]).

City	Location Description	Location Visualization
Świnoujście	Barlickiego Street. Near the port and ferry crossing. Proximity to the main public transport hub, with convenient connections to the main route towards Szczecin.
Kołobrzeg	Trzebiatowska Street. Near the MZK bus depot and the ring road. The direct vicinity of the bus depot—optimal for logistics and refuelling. Regional road DW102 is close, and the S6 expressway is easily accessible.
Stargard	Broniewskiego Street. In the immediate vicinity of the MPK Stargard bus depot, adjacent to national road DK10 and near DK20.

.

The research results are limited. The case study of the West Pomeranian Voivodeship in Poland was considered. Therefore, it is reasonable to continue the research and investigate the ability to locate the stations in other regions of Poland. Moreover, the potential demand for hydrogen refuelling from citizens (using hydrogen-powered cars) and the changes in average mileage of buses along the routes during the week, as well as situations of hydrogen leakage and other issues [84,85] were not considered in details. These data will significantly influence the station placement decisions that will be considered in our future works.

The selection of locations of bus refuelling stations may be discussed. For example, the locating of station near the Central Bus Station in Szczecin city was not considered, because it serves mainly intercity bus lines and congestion is often observed near its area. The location of bus refuelling stations near bus depots also may be considered. Moreover, the type of stations and needed equipment [86] will be considered by us in details in our future works.

The feasibility of the refuelling stations installation is based on calculation of the demand for hydrogen which may deal with the number of buses in operation. Therefore, bigger cities (over 100,000 inhabitants) were considered. It should be also noted that expected variation (growth/decline) of population, buses, passenger cars and other aspects may impact the establishment of the number and allocation of refuelling stations in the future (in case of 2040). According to official statistical data the population of West Pomeranian Voivodeship is decreasing [73]. That may impact the demand for public transport services and the number of buses operating in particular cities.

The rapid evolution of energy technologies necessitates a comprehensive approach to energy planning that accommodates not only hydrogen energy but also a spectrum of alternative energy sources, particularly in the context of the transport sector. While hydrogen has emerged as a promising clean fuel, discussions about energy transition should encompass various alternatives such as solid-state batteries, biofuels, and electric vehicle (EV) technologies.

Solid-state batteries, for instance, offer several advantages over traditional lithium-ion batteries, including higher energy density, reduced risk of fire hazards, and potentially lower costs with advancements in manufacturing technologies [87]. As research and development in this area progress, solid-state batteries could become a dominant energy storage solution in electric vehicles, providing opportunities for rapid charging and longer driving ranges.

Biofuels represent another viable alternative, as they are derived from renewable biological materials and can significantly reduce greenhouse gas emissions [88]. Their compatibility with existing internal combustion engine infrastructure makes them an attractive option for immediate applications in the transport sector, especially in aviation and maritime transport, where electrification presents more challenges.

Furthermore, innovative technologies such as solar-powered vehicles and hybrid systems combining multiple energy sources can contribute to a diversified energy portfolio [89]. For example, integrating solar panels into vehicle design could harness renewable energy directly, reducing reliance on external charging infrastructure.

To optimize energy planning, it is essential to build flexibility that allows for integrating rapidly evolving technologies and diversifying energy sources. In the future [90], by promoting synergy between hydrogen, solid-state batteries, biofuels, and other alternatives, a more holistic and robust approach to decarbonising transport can be achieved.

6. Conclusions

The aim of the article was to propose the conceptual location of infrastructure for fuelling of public transport vehicles with hydrogen in selected cities of the West Pomeranian Voivodeship, in particular Szczecin and Koszalin cities. This goal has been achieved. The conceptual location of hydrogen refuelling stations in these cities was proposed. The presence of hydrogen refuelling stations in cities is crucial to enable the operation of these vehicles in urban areas. A stationary hydrogen refuelling station should include, among others: tanks, dispensers and compressors.

Based on the achieved results the following recommendations may be formulated to be considered for implementation and development of hydrogen refuelling infrastructure in cities:

• Prioritize strategic locations—ensure that hydrogen refuelling stations are located near major public transport routes to maximize accessibility and usage by public transport vehicles. When choosing a dispenser, special attention should be paid to the pressure at which the vehicle is powered with hydrogen. The safety of hydrogen fuelling is extremely important and should be ensured so that the operation of hydrogen stations and the subsequent operation of vehicles takes place in a way that does not threaten the life of society.
• Pay dedicated attention to public awareness campaigns—implement educational programs to inform the public about the benefits and use of hydrogen-powered vehicles and refuelling stations, fostering acceptance and encouraging utilization.
• Conduct regular assessment—continuously monitor and evaluate the operational statistics of hydrogen-powered buses and adjust the placement and number of refuelling stations accordingly to meet changing demand and urban mobility patterns.
• It is important to engage local government, transportation authorities, and private stakeholders in the planning and development phases to create a cohesive strategy that aligns with the national hydrogen strategy and regional goals.
• Elaborate plan for future expansion—design the initial stations with future scalability in mind, allowing for easy expansion to accommodate anticipated increases in hydrogen demand and the growth of hydrogen-powered vehicles.
• Address economic and legal challenges—identify potential financial, regulatory, and legal barriers to the establishment of hydrogen refuelling infrastructure and work proactively to address these issues through policy advocacy and partnerships.
• Implement pilot projects—consider initiating pilot projects in the city to test the feasibility and operational effectiveness of hydrogen refuelling stations before broader implementation.

The use of hydrogen-powered vehicles in public transport in the West Pomeranian Voivodeship can help to develop the transport transformation, ensuring the sustainable development of the considered voivodeship. The development of the analysed infrastructure will facilitate the decision-making process of transport companies′ managers related to this transformation and the implementation of hydrogen-powered buses.

Our future research will focus on the further development of a methodology for determining the location of stations for fuelling vehicles with hydrogen. The application of mathematical optimisation techniques to identify the optimal station locations in the future will be considered. Moreover, the specific analysis related to the unexpected consequences or challenges associated with public subsidies, especially regarding market distortions or reliance on government support, will be analysed.

The research results will be of interest to infrastructure developers, public transport companies, and municipalities involved in making decisions related to the purchase of hydrogen-powered buses.