Electrifying Urban Fleet Buses: an Opportunity for a Decarbonised Urban Mobility

Authors: Marion Pignel, Thomas Lymes – Eurocities

A favourable environment to get rid of internal combustion engine buses.

Heavy-duty vehicles (‘HDVs’) are part of cities’ everyday life – they’re the trucks delivering supplies to local retailers, the coaches connecting towns and cities, and the buses carrying people around the city. As of 2021, 92% of buses in the European Union were still powered by diesel – according to the “Vehicles in use report” from ACEA (2023) – contributing significantly to CO2 emissions and urban air pollution. However, the winds of change are blowing. In the first half of 2023, electric bus sales represented 15% of the total volume. This is set to increase rapidly in the years to come as public transport decarbonisation plays a central role in the cities’ strategies for climate neutrality and air quality. 

As zero-emission buses are becoming mainstream in many European cities, let’s look at the ins and outs of this transition and the solutions and lessons learned from three European cities: Berlin (Germany), Turku (Finland) and Budapest (Hungary).

Berlin’s electrification efforts are guided by the Berlin Mobility Act from 2018. This piece of legislation gives guidance for different modes of transportation such as walking, cycling, and public transport. It is stated in the Act that public transport in Berlin should be decarbonised by 2030, and the Berlin public transport authority is acting with this aim in mind.

Urban bus fleet decarbonisation has been encouraged by various regulations, either local, national, or European, each focusing on different aspects of demand and supply. On the demand side, the Clean Vehicles Directive sets public procurement targets for low and zero-emission buses, with national goals for zero-emissions bus procurement ranging from 24% to 65% across two reference periods from 2021 to 2030. 

The newly adopted Regulation on the Deployment of Alternative Fuels Infrastructure (AFIR) indirectly supports electric buses, acting as an enabler, by setting deployment targets for heavy-duty vehicle charging points, with specifications for e-bus recharging infrastructure and encouragement for Member States to include public transport in national strategies. Complementing these regulations, EU funding instruments like the Recovery and Resilience Facility and the Alternative Fuels Infrastructure Facility are available to assist public authorities in procuring zero-emission buses and investing in necessary recharging infrastructure.

The European Commission’s 2023 proposal to revise the Regulation on CO2 emission standards for heavy-duty vehicles, including a phase-out of new internal combustion engine buses by 2030, marks a pivotal step in fully decarbonising bus fleets. 

This multi-faceted approach, combining demand-side legislation (procurement targets) with supply-side legislation (emission standards and infrastructure requirements), has allowed the market to take up quite rapidly in recent years. However, in certain cases, these measures were largely anticipated by bold local measures regarding the decarbonisation of bus fleets.

In Turku (Finland), Föli, the public transport company introduced the first electric buses in 2016 and as of 2022, 1/3 of the bus fleet is fully electric. 

The phase-out of combustion engine buses by 2030 comes at a time when public authorities have already started to decarbonise their public transport fleet. For example, cities such as Amsterdam (the Netherlands) and Copenhagen (Denmark) are planning for a fully zero-emission fleet by as early as 2025, and over half of all European capital cities are planning for a fully zero-emission fleet by 2040. While most of the central and eastern European cities are still drafting strategies for zero-emission buses (ZEBs), there are also promising case studies, for example, in Warsaw (Poland) or Sofia (Bulgaria). 

However, the phase-out of combustion engine buses by 2030 is still challenging for many local authorities, implying a rapid shift towards a relatively new technology. It likely means that cities’ public transport authorities will have to rely on electric- or hydrogen-powered buses for the supply of new buses post-2030. 

What solutions for the decarbonisation of urban buses?

The decarbonisation of urban buses involves several strategies and technical solutions, ranging from electric and hydrogen batteries to the use of biofuels such as biodiesels and biogas. These fuels can often be used in existing diesel engines with minor modifications. Certain cities, such as Madrid (Spain), stopped operating their last diesel bus in 2021 and focused instead on low-emission technology produced locally, i.e. biogas. Similar situations can be observed in cities located in Nordic countries or France. As demonstrated in a recent report from the European Court of Auditors (Special report 29/2023: The EU’s support for sustainable biofuels in transport – An unclear route ahead), the environmental impact of biofuels may not be deemed compatible with climate targets. However, the switch started by several European cities already implied millions of euros of investments in the refuelling and energy production infrastructure. To lessen the impact of the transition to zero-emission buses on local transport authorities’ budgets, the different contexts should be reflected in the relevant EU legislation. 

Urban buses are in a prime position for electrification as they operate predictable routes, which eliminates range anxiety. They’re usually stored in depots overnight where they can be charged, and they’re normally publicly procured, giving their purchase access to a wider amount of capital compared to the private transport market. Transitioning to electric buses is one of the most effective solutions, as electric buses produce zero tailpipe emissions and can be powered by renewable energy sources. 

Berlin chose electrification as their decarbonisation strategy after comparing the cost-effectiveness of different types of alternative fuels. After conducting many studies comparing different options, Berlin (Germany) opted for a “Flex charging strategy” – battery electric buses charged at depots and bus terminal stations, combined with opportunity charging for buses with long routes.

Pending challenges

Investment needs

The phase-out of the internal combustion engine (ICE) buses will imply that cities will likely need financial support from national or EU funding schemes. Even though the total cost of ownership of electric buses is getting more and more interesting for local transport authorities, upfront costs linked to the purchase of new rolling stock still pose many challenges for local transport authorities at a time when the effect of the energy crisis and post-covid recovery are still felt on local budgets. The European institutions should, therefore, multiply initiatives to support the purchase of zero-emission rolling stock.

Retrofit or not?

A study published by the French National Agency for Energy and the Environment (ADEME) highlights that urban buses present an interesting potential for retrofitting. Yet, despite its many benefits in terms of cost reduction and contribution to the circular economy, the technical upgrading of buses is still not seen as a widespread alternative, mainly because of the costs associated with the approval of retrofitted vehicles or retrofitting kits.

The Municipality of Budapest is looking at the optimisation of charging infrastructure and in-motion charging to make the electrification efforts more economically viable. Starting with in-motion charging also gives Budapest a little more time to see the progress in battery technologies and invest later in solutions with better technical features.

Adapting cities’ infrastructure to pave the way for electric buses.

Beyond vehicle purchase, the massive roll-out of electric buses underpinned by the 2030 ICE buses phase-out will also imply further investments in the relevant infrastructure to accommodate the use of zero-emission buses by local authorities. The types of investments will include upgrading grid capacity, establishing grid connections, renovating bus depots to allow for overnight charging, and potentially testing and installation of opportunity charging infrastructure along longer bus routes. Other challenges also relate to the size of bus depots, which is expected to grow for reasons related to fire hazards, as electric buses must not be parked too close to each other. This investment aspect constitutes an even bigger challenge in times of high inflation: a recent Eurocities survey also showed that 20% of the city leaders polled indicated that the current inflation may force them to reduce or postpone investments in public transport. EU funding instruments, such as the Alternative Fuels Infrastructure Facility, should therefore be extended to provide more opportunities for urban areas to apply for funding, and a massive European Net-Zero Infrastructure Investment Plan should be included as part of the next European Commission’s agenda 2024-2029.

The loss of service area on depots due to the presence of charging infrastructure, or the need to carry out the transition works while keeping full operation of the bus services are the major challenges faced in Berlin.

What about supply?

The supply of zero-emission buses can be challenging in many aspects, which can make procurement procedures more complex: delivery time for zero-emission buses is still too long. It may clash with the ambition of local authorities in terms of decarbonisation and the availability of spare parts for repair is still not guaranteed. The reliance on electric buses sourced primarily from third countries – mostly from China – may bring about certain complications. The ongoing anti-dumping inquiry initiated by the European Commission on the Chinese automotive sector will likely stir tensions between the two blocs. A potential EU-China trade war could have potential implications on the e-bus supply chain if things escalate. This situation highlights the importance of diversifying the sources of e-bus supply and strengthening the European industrial automotive base to secure a smooth decarbonisation of public transport.

Some challenges remain for Föli, such as a lack of supply of certain types of vehicles among European manufacturers and the impossibility of retrofitting their existing vehicles for alternative fuels.


Achieving the goal of having 100% zero-emission buses on the roads has become a key focal point in the decarbonisation strategies of European cities. Recent advancements at the EU level are likely to expedite this trajectory. The forthcoming European Commission will play a crucial role in facilitating a seamless implementation of this transition, drawing insights from the experiences of cities already engaged in this transformative journey.


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