Energy Transition in Public Transport: A Cost-Benefit Analysis of Diesel, Electric, and Hydrogen Fuel Cell Buses in Poland’s GZM Metropolis

Abstract

Energy transformation is one of the processes shaping contemporary urban transport systems, with public transport being the subject of initiatives designed to enhance its attractiveness and transport utility, including electromobility. This article presents a case study for a metropolitan conurbation—the GZM Metropolis in Poland—considering the economic efficiency of implementing buses with conventional diesel engines, electric buses (battery electric buses), and hydrogen fuel cell-powered buses. The analysis is based on the cost-benefit analysis (CBA) method using the discounted cash flow (DCF) method.

1. Introduction

The aim of the article is to compare the economic efficiency of three variants of the development of the public transport operator’s rolling stock, i.e., further use of combustion vehicles, purchase of battery electric buses (BEBs), and purchase of fuel cell electric buses (FCEBs). The comparison in accordance with the CBA methodology will include both the financial aspect and the impact on the environment. The authors will also identify key variables influencing the result of the analysis. The analysis will be carried out based on a real case study covering an investment project implemented by the Upper Silesian-Zagłębie Metropolis (GZM), which is one of the largest organizers of public transport in Poland. Using the case study method allows for an in-depth understanding of complex phenomena in their natural context. It is a qualitative research method used in various disciplines, including economics and management sciences [1].

This paper focuses on a specific case study to demonstrate the practical results of implementing alternatively powered buses and highlight key issues related to this process. The results presented in this article contribute to the current state of knowledge, based on a case study of an urban agglomeration—the only one in Poland with metropolitan status—the GZM Metropolis. The rationale for selecting this urban agglomeration is as follows:

−

Continued publication of the results of scientific and research work on the implementation of buses with alternative drives, with the GZM Metropolis as a case study [2,3,4,5];

−

Specific conditions for the discussed practical issues resulting from the specific nature of the GZM Metropolis, which are presented in the next paragraph.

For the purpose of organizing the article, the primary stakeholders in the public transport sector are first outlined, including an explanation of the roles fulfilled by these entities (see

Table 1. Public transport market stakeholders’ status.

Stakeholder	Operating Conditions
Public transport organizer	In the Polish legal and institutional framework, the organizer of public transport is defined as a public entity responsible for planning, coordinating, and overseeing the provision of public transport services within a specified area. In most cases, the role of public transport organizer is fulfilled by the municipality or, in more developed areas, by an inter-municipal association. Main responsibilities: defining transport networks and schedules, organizing tenders for transport service providers, setting service quality standards and fare policies, and ensuring accessibility and integration of transport modes. The public transport organizer is also responsible for its financing. Currently, in the domestic context, fare revenues cover approximately 20–35% of the system’s operational costs. The remaining funds are provided by municipalities in the form of subsidies.
Public transport operator	A public transport operator is an entity (public, private, or public–private) contracted by the transport organizer to provide passenger transport services within a defined framework. The operator is responsible for the day-to-day execution of services, including vehicle deployment, staff management, and adherence to contractual quality standards.
Internal entity	Pursuant to the Act on Public Collective Transport of 16 December 2010 and in accordance with Regulation (EC) No. 1370/2007, an internal entity is an enterprise established to perform public transport services within the public transport system. In the case of an internal entity, it is permissible to conclude a public service contract through direct award, thereby exempt from competitive tendering procedures. An internal entity must meet several key conditions: it must be controlled by the public transport authority, and it must receive compensation in the form of a public service obligation payment. Typically, the internal entity functions as a commercial company under business law and earns a so-called reasonable profit that can be utilized for enterprise development.
Local government units	Local government units are responsible for organizing public transport to ensure efficient operation and maintain an appropriate quality of life for residents. They may accomplish this in several ways: − Direct organization—establishing and operating the transport system independently; − Delegation to another municipality—entrusting transport organization to a different local government unit; − Joining an inter-municipal association—participating in a collaborative transport union with other municipalities. Irrespective of the selected market organization form, territorial self-government units retain financial responsibility for the public transport system.

Source: own study.

).

The case study presented in the paper stands out from the average urban area (city) due to, among others, the following conditions closely related to the subject of the research, i.e., the process of energy transition in public transport:

−

A polycentric urban agglomeration, i.e., a conurbation of 41 cities, among which there is no single dominant central city, as opposed to monocentric agglomerations with one central city.

−

The area of operation of public transport is 41 member cities of the GZM Metropolis covering an area of 2.500 km², with a population of 2.1 million, divided into 41 separately managed cities.

−

Each of the 41 cities has its own local authorities, its own specific transport needs, its own transport policy, and its own socio-economic development plans.

−

The technical transport infrastructure consists of networks of land transport systems, i.e.,

○

A network of urban streets in 41 cities connected by suburban roads of the highest technical standards and road categories (motorways and expressways);

○

A bus transport network providing transport services to all 41 cities;

○

A tram transport network that is technically coherent across the 13 cities that constitute the core of the Metropolis;

○

A rail transport network that is technically coherent in terms of passenger transport and is currently being expanded with additional track infrastructure that will ultimately support internal transport within the Metropolis (Metropolitan Railway).

−

The organizer of public transport is the Metropolitan Transport Authority (MTA), whose tasks include, among others, planning and organizing bus and tram transport (a network of bus and tram lines with timetables), as well as participation in the processes of financing and settling the costs of public transport, the stakeholders of which are the authorities of member municipalities. In [5], public transport funding and public transport organization models for the MTA are presented.

−

The structure of transport needs and the flows of passengers and vehicles for individual and public transport are complex for the following reasons:

○

It constitutes traffic within individual towns—urban trips over relatively short distances.

○

It constitutes traffic between towns directly adjacent to each other—including trips of an urban nature, i.e., also over relatively short distances.

○

It constitutes traffic between towns not directly adjacent to the Metropolis—trips over relatively long distances and travel times that vary significantly throughout the day due to congestion occurring both in the urban road networks and on sections of rural roads connecting towns within the Metropolis.

○

It constitutes traffic between towns within the Metropolis and its surroundings, i.e., with towns surrounding the Metropolis—trips of both short and long journeys—depending on the endpoints of the trip.

○

It constitutes transit traffic—transit trips both from the perspective of individual towns within the Metropolis and from the perspective of the entire Metropolis.

○

It constitutes traffic serving the Katowice International Airport—trips complementary to air travel, served by individual transport vehicles and public transport—buses and trains.

These factors shape passenger transport needs and traffic flows in the Metropolis’ transportation systems and constitute a set of framework conditions for the organization, operation, costs, and financing of public transport services in the GZM Metropolis. The issues presented in this paper regarding the implementation of buses with alternative drives have been systematically separated from these framework conditions.

Systemic relationships with key conditions that have already been investigated using algorithmic approaches in this case study can be found, among others, in other works. The author of [6] presents an algorithm for the economic evaluation of the bus fleet conversion process. The algorithm takes into account the following system elements: input, output, evaluation variables, beneficiary, and user variables. Previous work [2] presented the dilemmas of selecting appropriate methodological instruments that should support the process of converting a city’s conventionally powered bus fleet to an electric bus fleet. The applied process approach takes into account the staging of the conversion process, variants of activities at individual stages, and variants of the target fleet structure related to a specific conversion strategy. The fleet conversion process was based on the identified economic conditions [3] and a detailed economic model algorithm developed and implemented in a dedicated analytical and simulation tool [4]. Computational experiments conducted in the process of algorithmization and verification of the mentioned algorithms, as well as the results of the analysis presented in [5], clearly indicate the high costs of purchasing buses and devices for charging bus traction batteries. These are the basic problems of electromobility in smart urban mobility related to electricity management and the energy efficiency of electric vehicles and their traction batteries, a review of which is provided in [7,8].

The paper is structured as follows. Section 1 justifies the purpose and scope of the paper in relation to the current challenges of energy transition in public transport. Section 2 provides a literature review of the key issues presented in the paper. Section 3 presents the methodology employed in the conducted research. A case study of one of the largest Polish organizers of public collective transport was utilized. The chapter also includes a characterization of the CBA method. Chapter 4 contains the research results, which were then discussed and compared with other publications. The final chapter provides a summary and conclusions.

2. Literature Review

The following paragraphs present key findings from the literature review that justify the topic and scope of this paper. In particular, the following issues are highlighted: barriers to the implementations of BEBs (battery electric buses), decision-making in the process of optimizing the number of electric buses, charging infrastructure, energy consumption, and key factors in the planning process.

The authors in the publication [9] draw attention to the following barriers to the implementation of BEBs (battery electric buses):

• General barriers, including technological, financial, and institutional barriers: the main technological barrier is the limited driving range of battery buses compared with conventional buses, which is approximately 200–250 km, depending on weather and road conditions.
• Barriers related to the impact on the power grid: these barriers are caused by different strategies and systems for charging battery buses, which cause the charging process to be non-linear and have a harmful effect on the power grid; the non-linearity of the process is caused by, among others, charging strategies such as slow plug-in chargers at bus depots but fast plug-in or pantograph chargers located at terminals or bus stops and, moreover, overhead contact lines or inductive charging at lines.
• Barriers related to specific energy consumption ranging from 0.76 to 2.79 kilowatt hours per kilometer (kWh/km), on average 1.65 kWh/km.
• Barriers in the process of operating the bus fleet related to the reliability of bus line service with different battery charging strategies and the limited driving range of battery buses (approximately 200–250 km): therefore, when planning the operation of bus lines with battery buses, the driving range, availability of battery charging devices, and the charging strategy should be taken into account. When planning and operating the bus network, it is also worth considering the mixed structure of the bus fleet, i.e., one part of the fleet may consist of battery buses, and the other part of it may consist of buses with conventional drive, i.e., with a diesel engine.
• Barriers to maintaining fire safety: i.e., during operation, adverse effects occur, such as overheating of lithium-ion batteries (LIBs) and, in extreme cases, rupture of battery cells. Such failure can cause internal and external short circuits, explosions, and fires, the extinguishing of which is very difficult and dangerous.

Considering the electric bus fleet transition problem, the authors of the publication [10] presented a comprehensive tool for decision-making in the process of optimizing the number of electric buses that should be included in the fleet of a transport company in a given period of transformation of this fleet to a more ecological fleet. The result of this optimization is a bus replacement plan that considers purchase costs, revenues from recovery, operating costs, investments in charging infrastructure, and demand charges. The developed optimization process considers the use of various options for charging infrastructure—including slow and fast plug-in stations, overhead pantograph chargers, and inductive (wireless) chargers.

In relation to the BEB (battery electric bus) charging infrastructure, the authors of [11] present the results of an analysis of the cost competitiveness of different types of BEV bus charging infrastructure. This analysis considers, among others, charging stations, charging lanes (using charging while driving technology), and battery exchange stations. The result of this analysis is the optimal deployment of different BEV charging facilities along the public transport lines and determining the optimal size of the BEV fleet, as well as their batteries, to minimize the total infrastructure and fleet costs, while guaranteeing the frequency of services and meeting the needs of the public transport system.

The analysis of the benefit-to-cost ratio for the initial phase electrification of BEB is presented in the publication [12]. The research results are presented on the example of the extensive public bus network of Delhi, India. The case study included two scenarios: compressed natural gas (CNG)-to-electric and diesel-to-electric bus transitions. The research included sensitivity analysis to evaluate how the available electrification budget and charging power affect the benefit-to-cost ratio and decisions related to route and terminal electrification. One of the basic conclusions indicates that at least 30% of electricity should come from clean energy sources to maximize the environmental benefits of bus electrification.

In publication [13], an operating mode binning method to assess on-road energy consumption and well-to-wheel (WTW) air pollutants emissions of BEBs under complex real-world usage patterns is presented. The method considers operating conditions, i.e., 18 various patterns by average speed, loading mass, and air conditioner usage. One of the important results of the research is the confirmation that the regenerative brake system is effectively functioning under deceleration conditions.

The Electric Bus Implementation Handbook [14] emphasizes the importance of the following factors in the planning process: developing mission objectives, defining key performance indicators, engaging stakeholders, and identifying sources of financing. These factors are important because of the high degree of interdependence between the different combinations of technologies resulting from the bus design, battery storage system, and charging infrastructure and route planning decisions. This also relates to the need for early involvement of power plants in the BEB implementation process to consider any potential adjustment of the power grid to the additional electricity supply needs of the charging points as well as setting electricity rates. In the BEB route design process, it is indicated to consider such factors for optimization reasons as the following:

• Physical characteristics of the routes including route length, gradient, number of stops affecting energy consumption when starting and energy recovery when braking, etc.;
• Characteristics of the bus timetable including travel speed, number of bus rides, service of rides by buses with different drive systems, etc.;
• Vehicle charging characteristics including electricity consumption and strategies and charging points.

The listed technical and organizational aspects should be supplemented with human factors related to, among others, training of drivers and technical service personnel. Inspection of charging infrastructure and emergency preparedness plans are also very important issues. The justification for considering the listed factors is also emphasized in earlier studies [2,3,4,6]. On the other hand, a review of selected detailed technical problems concerning the construction and use of electric vehicles is presented in studies [7,8].

In the article presenting the case study for Bogota, Columbia [15], the authors also emphasize the importance of the planning process—especially prudent planning with special attention to solid forecasts of expected costs and benefits related to the implementation of BEBs. The Future Mobility Calculator was used in the analyses—a tool that, for a given range of city-specific inputs (general city data, mobility data, charging infrastructure data, and cost data) and a projected electric transport uptake scenario for 2035 and 2050, identifies the quantity and cost of infrastructure required. It also quantifies some of the emissions benefits that would result from an investment in electric transport infrastructure, based on input data and listed assumptions [16]. For the case study of Bogota, the following input data were assumed: population, average annual population growth rate, city population density [residents per square km], per capita annual income, total average electricity consumption in city per day, and composition of electricity generation mix (coal, natural gas, oil, and renewables—hydro, wind, and solar power). The calculation results are the number of BEBs in the bus fleet, slow chargers and fast chargers needed for the bus fleet, electricity needed for the bus fleet, depot average electric power demand, avoided GHGs (greenhouse gases), PM10 (particulate matter with a particle diameter not exceeding 10 μm) and NO (nitrogen oxides), and cost-benefit analysis results, which in this case study indicate that approx. 70% of the total costs are the costs of purchasing buses, and approx. 25% of the total costs are the costs of installing and maintaining the BEB charging infrastructure.

Study [17] presents the state of knowledge (2021) in the field of the implementation of BEBs in cities. Among other things, the analysis of the BEB system topology and charging technology was presented, with particular emphasis on power electronics systems, and key technical requirements facilitating operation were presented—considering vehicle scheduling, charger location optimization, and charging management strategies. The conclusions from the conducted analyses were indicated primarily as follows:

• The battery capacity is a key element of the BEB drive system as it provides only the power to drive the BEB and covers the energy requirements of various other subsystems such as HVAC (heat, ventilation, and air conditioning system); therefore, an accurate assessment of the energy consumption of all BEB systems is a must for bus operators.
• In addition to the battery, the charging infrastructure plays a fundamental role in the implementation of BEB. It is equipped with a PEC (power electronic converter unit) to convert AC current from the electrical grid to DC current to charge the BEB battery; due to the high power required, a modular design of chargers is often considered, and additionally, such a design enables the integration of RESs (renewable energy resources), and ESSs (energy storage systems) can be easily integrated. Therefore, real-time, multi-criteria intelligent charging management strategies with V2X (vehicle-to-anything, is a term that references technologies that use the energy in the batteries of plug-in electric vehicles (PEVs) for any purpose outside the vehicle) functionalities should be considered when planning large bus fleets—especially in the case of bidirectional chargers for V2X applications and emerging WBG (wide bandgap semiconductor materials) devices operating at higher switching frequencies.
• In the case of a large BEB fleet, both bus traffic planning and charging planning are necessary—it should be investigated which charging concepts (depot charging, opportunity charging, or dynamic wireless charging) best suit the needs of the bus routes in a given city and where the charging infrastructure should be located, taking into account intelligent charging management to mitigate the impact on the distribution network and enable V2X services.

A review of the literature indicates that researchers undertake studies comparing the effectiveness of various types of propulsion systems used in buses. The scope of the analyses and the selection of methods vary and are dependent on the study’s objective. One of the methods employed is the total cost of ownership (TCO), which is based solely on financial flows [18]. Another approach, based exclusively on environmental effects (the reduction in greenhouse gas emissions), is presented by well-to-wheel (WtW) analyses [19]. Life cycle assessment (LCA) analyses are also used in the context of efficiency research [5]. This article utilizes the cost-benefit analysis (CBA) method (described in more detail in the next section). The use of this method itself is not innovative. However, a characteristic feature of the applied methodology is the selection of analysis parameters derived from specific technical, organizational, and financial conditions. The simulation presented in this paper comprises an interesting case study of a developed urban area in Poland—a country facing significant challenges from the perspective of energy transition, which results in one of the highest electricity price levels in Europe.

3. Materials and Methods

3.1. Characteristic of the Study Area

The analyzed investment project was implemented by the GZM Metropolis in Poland. The entity is a metropolitan association, i.e., an organization associating municipalities and counties located in the central part of the Silesian Voivodeship (in Poland). This area is very important from a demographic and economic point of view. Over 12% of the GDP of the entire country is generated in the Silesian Voivodeship, of which a significant concentration of activity occurs in the GZM area. The GZM area includes 41 municipalities, inhabited by approx. 2.1 million inhabitants (31 December 2023). Additionally, several neighboring municipalities are served under agreements. GZM is the largest organizer of public transport in Poland in terms of the size of the area served. The network includes over 500 communication lines, which are served daily by approx. 1500 vehicles. On behalf of GZM, operational work is carried out by several municipal and private operators.

The analysis is a case study covering one of the largest investment projects in zero-emission rolling stock. The value of the project amounted to approx. PLN 100 million and included the purchase of FCEBs (8 units), BEBs (22 units), and charging infrastructure. Data prepared as part of the process of obtaining funding became the basis for preparing this article. The project is currently in the implementation phase after a positive assessment and granting of funding at the level.

3.2. Organization and Financing of the Development of Public Transport

Public transport plays an important role in the functioning of urban areas, providing a foundation for balancing urban mobility [20]. This system is capable of handling large passenger flows and is a real alternative to individual transport services. The models of organizing the public transport market are determined by legal regulations, especially taking into account the public utility of such services. The practice of organizing the public transport market indicates two main models of organization: the use of competitive mode in the form of public procurement or direct conclusion of an entrustment agreement with the so-called internal entity. The analysis of contracting public transport services in Poland indicates the dominance of the model based on the so-called internal entity in accordance with Regulation (EC) 1370/2007 and procurement directives 2014/24/EU and 2014/25/EU [21]. This model ensures relatively high flexibility of cooperation between the organizer and the public transport operator, which is particularly important from the point of view of investment in rolling stock and infrastructure.

The financing of public transport services in Poland most often takes the form of a so-called gross cost agreement, which assumes that the operator’s remuneration is not dependent on the demand for transport services, ticket revenues, and the number of passengers transported. In this model, the operator’s remuneration is paid as the product of the performed operational work and the contracted unit rate of the cost of a vehicle kilometer. The main task of the operator from the financial and organizational point of view is to maintain transport capacity at a specified level of costs for the transport company. Such a model also determines investment strategies in the development of the rolling stock base. The experience of implementing zero-emission rolling stock indicates two investment solutions:

• Purchase of rolling stock and infrastructure by the organizer of public transport and transferring it to the public transport operator;
• Purchase of rolling stock and infrastructure directly by the public transport operator.

The first of the above-mentioned solutions is characterized by a lower risk in terms of maintaining the durability of the project. The organizer’s functions are performed by a local government unit, which is part of the public finance system, which guarantees the continuity of its functioning. The organizer may transfer the purchased rolling stock for use to an internal entity, or another operator selected in a competitive procedure.

The second solution involves the purchase of rolling stock directly by the operator, but in this case, it is necessary to prove the financial capacity of the company to implement the investment and to demonstrate a sufficiently long duration of the transport contract.

In the public transport system, revenues from tickets cover about 30–40% of operating costs (in the case of relatively small cities, this indicator is even lower). The deficit that arises is covered by the organizer (the public sector). This situation also determines the strategies for purchasing zero-emission rolling stock. Because vehicles of this type are much more expensive than combustion vehicles, national and EU funds play a key role in financing investments [22].

3.3. Methods and Data

The comparison of different forms of drives, i.e., ON (diesel engine), BEB, and FCEB, was carried out based on the CBA method, which considers both financial conditions and the impact on the environment. The assumptions for the analysis were adopted in accordance with the provisions of the Blue Book for the urban transport sector and national sector publications. The assumptions adopted for the analysis were as follows:

• The analysis was carried out over a 10-year horizon, which corresponds to the rolling stock depreciation period.
• The analysis was carried out at constant prices (excluding inflation).
• Due to the selection of the analysis period, replacement costs and residual value were omitted.
• Inputs and costs used in the economic analysis were adjusted to shadow prices.

Data for the analysis were obtained from the technical specifications of the rolling stock and from the experience of domestic operators using zero-emission vehicles. Monetization of external effects, including the calculation of avoided costs of pollutant and CO₂ emissions, was determined based on the recommended unit cost tables published by the Centre for EU Transport Projects, acting as an intermediary institution in the preparation and implementation of transport investments financed from European Funds in the 2014–2020 and 2021–2027 perspectives. Considering that the original project involved the purchase of 30 buses, a comparative analysis between ON, BEB, and FCEB was conducted for 30 vehicles.

3.4. Methods of Analysing the Efficiency of Rolling Stock Investments

Cost-benefit analysis (CBA) is an economic evaluation tool used to assess the feasibility of projects, policies, or investments by systematically comparing their costs and benefits. The theoretical foundations of CBA are rooted in welfare economics and aim to maximize social welfare by ensuring efficient resource allocation. This method is one of the methods of determining the effectiveness of an investment in an assumed time horizon. This method is particularly used to assess public projects because in addition to financial flows, it also considers the so-called economic flows illustrating the impact of the undertaking on the environment and focuses on net benefits for society [23]. CBA is characterized by a long-term perspective; in the case of transport projects, a period of 10–30 years is most often assumed. The analysis has a quantitative dimension; the obtained result is expressed numerically and calculated in an objective manner, based on appropriate calculation models. An incremental and differential approach is used—the calculation is based on cumulative flows for the assumed period, and the obtained results are compared with alternative investment variants or the so-called no-investment variant. The CBA method has been used to assess transport projects for over two decades [24]. Proper assessment of transport projects using the CBA method allows for the most efficient allocation of public resources [25,26]. In the case of the so-called large projects (with eligible costs exceeding EUR 50 million) applying for funding from European Union funds, the CBA method is a mandatory element of the feasibility study for the investment. A project is considered economically justified if its net present value (NPV) is positive, meaning the benefits outweigh the costs.

$$NPV=\sum _{t=1}^n{\displaystyle \frac{{CF}_t}{{(1+r)}^t}}-I_0$$

NPV—net present value

CFt—cash flow in t-period

r—discount rate (year)

I₀—investment costs in the base period

The aim of the analysis is to determine the efficiency of the project using the net present value (NPV) method. The individual stages of the analysis differ in the scope of data used for calculations, as shown in

Table 2. Basic efficiency indicators of CBA method.

Indicator Designation	Data Range	Interpretation of the Indicator
Financial analysis
FNPV—financial net present value	− Capital expenditure − Operating costs − Project revenues	The higher the value of the indicator, the higher the financial efficiency of the project. In the case of public projects, FNPV reaches negative values, which means lack of efficiency.
FRR—financial rate of return	− Capital expenditure − Operating costs − Project revenues	A project is financially efficient if the calculated rate of return is higher than the cost of capital (denoted as the discount rate).
Economic analysis
ENPV—economic net present value	− As in financial analysis, after converting values to shadow prices * − Monetized externalities	The higher the value of the indicator, the higher the economic efficiency of the project. In the case of public projects, ENPV should reach positive values.
ERR—economic rate of return	− As in financial analysis, after converting values to shadow prices * − Monetized externalities	A project is economically efficient if the determined rate of return is higher than the cost of capital (denoted as the discount rate).
B/C—benefit–cost ratio	− As in financial analysis, after converting values to shadow prices * − Monetized externalities	The higher the value of the indicator, the higher the value of the benefits in relation to the costs.

* shadow process—A shadow price is the estimated monetary value of a good, service, or resource that does not have a market price, such as an environmental impact or a public utility service. It serves as a proxy value, reflecting the value of an item based on what must be given up to obtain one more unit, and is used in economic analyses like cost-benefit analysis to incorporate the true social and economic impacts of projects and policies. Source: [23].

.

4. Results and Discussion

4.1. Analysis of Investment Expenditure and Operating Costs

Technological progress in the field of ecology, especially in the initial phase, is characterized by low financial efficiency. Undoubtedly, the high investment costs pose a barrier to the implementation of zero-emission buses. On the other hand, operating costs often depend on several factors. The table presents the basic cost characteristics of the analysed fleet solutions.

The following key investment cost drivers were identified: capital expenditure (CAPEX) and operating costs (OPEX). In the scope of CAPEX, the purchase of vehicles was included as a key expense. Due to the diverse nature of the charging/refueling infrastructure, the cost was omitted because of the following:

• In the case of diesel vehicles, transport companies either have their own refueling facilities for a long time or use publicly available infrastructure, and as a result the cost of infrastructure is negligible.
• In the case of BEBs, various solutions can be used; for the purposes of the analysis, the purchase of a more expensive vehicle equipped with a relatively large battery was taken into account, which allows for daily operation on the communication line and is charged at night with a plug-in charger (the share of the cost of the plug-in charger is included in the vehicle price).
• In the case of FCEBs, the cost of building new infrastructure is very high, which will clearly distort the calculations, while the number of public stations that can be used to refuel hydrogen for buses is growing, which justifies omitting the cost of infrastructure in this case.

The total amount of investment outlays is therefore dependent on the cost of purchasing a single vehicle. The second component of the analysis is operating costs. The analysis shows that at the assumed prices, the cost of driving 1 km is the cheapest in the case of BEBs, while significantly the most expensive in the case of FCEBs (fuel cell electric buses). For the purposes of the analysis, an annual mileage volume of 60,000.00 km was assumed. The data subject to analysis are presented in the

Table 3. Investment expenditures and operating costs—assumptions for analysis (net, PLN).

Category	ON	BEB	FCEB
Purchase price	1,000,000.00 [PLN]	2,600,000.00 [PLN]	3,200,000.00 [PLN]
Annual mileage	60,000.00 [km]	60,000.00 [km]	60,000.00 [km]
Energy/fuel consumption	35.00 [l/100 km]	1.10 [kWh/km]	8.00 [kg/100 km]
Energy/fuel cost	5.00 [PLN/l]	0.90 [PLN/kWh]	40.00 [PLN/kg]
1 km cost [PLN]	1.75 [PLN/km]	0.90 [PLN/km]	3.20 [PLN/km]

Source: data from public transport entities (31 December 2023).

.

4.2. Analysis of the Impact on the Enviroment

The key aspect of the CBA method is the impact of a given investment on the system environment. In the case of this type of investment, the most important component is the impact on the natural environment. The analysis assumes a constant transport demand, which results from the fact that domestic experience indicates that the type of rolling stock (its drive, year of manufacture, and equipment) has practically zero impact on increasing the demand for public transport. Noise costs were also omitted due to the specificity of this issue requiring acoustic tests. The essence of rolling stock changes is the increase in the share of zero-emission vehicles. The following assumptions were made in the analyzed comparison:

• Diesel buses meet the Euro VI emission standard.
• BEB vehicles are considered zero-emission because the engine does not emit pollutants or GHGs (greenhouse gases), while considering Poland’s energy mix, in accordance with recommendations of CEUTP (Centre for EU Transport Projects) (https://www.cupt.gov.pl/en/ceutp/about-us/, 20 June 2025), the final consumer emission is 0.781 kg/kWh of electricity,
• FCEB vehicles are considered to be completely emission-free.

The base variant of the analysis is the emission of diesel buses, which, assuming the project (30 vehicles, 60,000 km annual mileage), generates the following pollutants, to which financial costs were also assigned (

Table 4. Types and costs of diesel bus emissions.

Cost Category	Emission Volume [kg]	Average Financial Equivalent (Indicator for 2025) [PLN]	Percentage Share by Financial Equivalent [%]
Carbon dioxide CO2	1,696,226.81	767,671.40	89.07
Nitrogen oxides NOx	1074.60	87,028.91	10.10
Hydrocarbons HC	180.00	694.18	0.08
Particulate matter PM	4.14	6432.04	0.75

Source: own study.

).

The conversion of emissions into financial values was carried out based on the unit cost tables developed by CEUTP; these values are recommended for use in CBA analyses for projects applying for EU funding.

4.3. Comparison of the Effectiveness of Variants

As a result of the adopted assumptions and the conducted analysis, the financial and economic efficiency values of three project variants were determined (

Table 5. Results of CBA analysis for variants.

Index	Diesel Buses	BEB	FCEB
FNPV/C [PLN]	−33,123,452.34	−76,182,471.08	−141,715,819.28
FRR [%]	-	-	-
ENPV [PLN]	−40,321,560.15	59,819,972.67	24,117,659.54
ERR [%]	-	80.56	23.58
B/C	-	1.56	1.17

Source: own study.

).

The results indicate that the most effective solution is to invest in BEB electric rolling stock. This solution is supported by zero emissions and lower investment and operating costs than in the case of FCEBs.

Comparison of two alternative fuel technologies indicates higher economic efficiency of BEBs under the adopted assumptions. The obtained results are primarily influenced by high investment outlays and higher operating costs per 1 km.

The study incorporated certain simplifications. A crucial aspect is the issue of hydrogen refueling infrastructure. This represents a significant investment that could be financed either through public funds or by entities such as public transport operators. Currently, within the GZM (Upper Silesian-Zagłębie Metropolis) area, there is already a publicly accessible hydrogen refueling station in operation (built by Poland’s largest fuel distributor—Orlen). For this reason, this element was excluded from the analysis.

However, for battery electric buses (BEBs), the costs of plug-in chargers were included in the assessment. This assumption was made because no public charging infrastructure would be capable of recharging the buses within the required charging time.

The above simplification is justified given the current state of hydrogen refueling infrastructure development in the GZM area. However, it is worth noting that the expansion of hydrogen refueling infrastructure could, in the long term, have a significant impact on the obtained financial results.

Should the decision be made to build a dedicated hydrogen refueling station, for instance, at a bus depot, it would be necessary to account for both the refueling infrastructure itself—which includes components such as a compressor, storage tanks, etc.—and the vehicles required to transport the hydrogen from the distributor to the station. The average cost of a new station is approximately PLN 30–40 million.

In contrast to electric chargers for BEBs (battery electric buses), hydrogen refueling is considerably faster, taking approximately 20–30 min. A full vehicle tank typically provides sufficient energy for an average of two days of operational service. Under these conditions, reliance on a public hydrogen station is feasible for a fleet size of approximately 20–30 vehicles. Considering that the current difference in ENPV (expected net present value) between FCEBs (fuel cell electric buses) and BEBs is approximately PLN 35 million, the necessity to construct a private station beyond a certain fleet size may become a critical factor influencing the level of economic efficiency [27].

However, one cannot exclude the possibility of public refueling station expansion in the long term, particularly given the substantial commitment of the government and public funds toward implementing the Green Deal.

4.4. Sensityve Analysis

The sensitivity analysis is conducted by varying a single parameter (the variable under study) while holding all other parameters constant and then assessing its impact on standard performance indicators (for economic and financial analysis respectively). For the subject project, we analyzed the influence of the following critical variables: capital expenditures (CAPEX) and operational expenditures (OPEX)—please refer to

Table 6. Impact of key variable changes on FNPV/C.

Variable	BEB	FCEB
CAPEX +1%	−0.743%	−1.570%
CAPEX −1%	−0.217%	1.570%
OPEX +1%	−0.217%	−0.385%
OPEX −1%	0.217%	0.386%

Source: own study.

and

Table 7. Impact of key variable changes on ENPV.

Variable	BEB	FCEB
CAPEX +1%	−0.887%	−1.780%
CAPEX −1%	0.887%	1.780%
OPEX +1%	−0.263%	−0.657%
OPEX −1%	0.263%	0.657%

Source: own study.

.

The sensitivity analysis indicates that the FCEB project is particularly vulnerable to changes in key variables. Regarding the impact on ENPV (economic net present value), the level of capital expenditures (CAPEX) proves critical—a 1% change in investment costs results in a greater than 1% variation in the efficiency indicator.

This finding carries particular significance for potential project parameter modifications, such as scenarios where the efficiency analysis would need to incorporate additional costs for hydrogen refueling station construction.

5. Conclusions

Modern and zero-emission solutions in public transport are an important direction of development. EU regulations on co-financing projects for the purchase of rolling stock practically make it impossible to purchase combustion vehicles. In the context of transforming public transport toward zero emissions, hydrogen-powered buses (FCEVs—fuel cell electric vehicles) and battery electric buses (BEVs—battery electric vehicles) are the two main technologies competing for the title of the most ecological solution.

In the context of transforming public transport toward zero emissions, hydrogen buses (FCEBs) and battery electric vehicles (BEBs) are the two main technologies competing for the title of the greenest solution. BEBs are currently greener in most cases as most of the hydrogen (~95%) comes from fossil fuels. The greenness of FCEBs depends on the H₂ production method and can range from 0 kg CO₂ in the case of obtaining hydrogen from electrolysis from RES to 9–12 kg CO₂/kgH₂ in the case of obtaining hydrogen from methane.

In most cases, BEVs are more environmentally friendly due to higher efficiency and the fact that hydrogen is mainly produced from fossil fuels. In the future, if hydrogen is produced exclusively from renewable energy, FCEVs can become competitive, especially in heavy transport and on long routes, where BEVs have range limitations.

It should be emphasized that each variant of zero-emission buses requires significant initial investment outlays, which may pose a substantial barrier to the development of public transport, particularly in areas with limited financial resources—such as economically disadvantaged regions.

However, beyond purely economic considerations, there is a clear political imperative. The pressure to reduce carbon emissions in transport stems directly from European-level regulations. The EU’s climate policy has been continuously evolving, with its most current framework being the European Green Deal. On 11 December 2019, the European Commission adopted this strategy, setting the ambitious goal of achieving climate neutrality (net-zero greenhouse gas emissions) by 2050. If successful, Europe would become the first climate-neutral continent.

The European Green Deal represents a new growth strategy for the EU, aiming to transform it into a sustainable, climate-neutral economy without compromising socio-economic progress or the development of a fair and prosperous society.

Further reinforcing this commitment, on 14 July 2021, the European Commission unveiled the “Fit for 55” legislative package on climate and energy. This initiative includes proposals to revise and update EU legislation while introducing new measures to align policies with the climate targets endorsed by the European Council and Parliament. Following UN conventions, the European Commission not only promotes the vision of the Green Deal but also implements practical economic policy programs to support this transition.