Fleet-wide level adoption of electric buses has been growing worldwide as municipalities look for ways to reduce their carbon footprint and dependence on fossil fuels. Battery electric busses, plug-in hybrids, fuel cell busses and trolley busses are all included in the definition of an e-bus, and all types have seen significant growth recently. Since 2012, around 8500 e-buses have been registered in Europe, with Germany, the UK, and France registering over 500 e-busses each. In 2021 alone, over 3200 electric buses were registered in Europe. As a proportion of the overall fleet, e-busses are expected to grow to over 65% by 2040. Additional studies expect two-thirds of all new registrations to be zero-emissions busses by 2030.
All major vehicle manufacturers are pivoting towards e-bus production and produce a variety of sizes and technologies. Chinese automakers BYD and Yutong Bus continue to drive the massive adoption of e-buses in China, delivering thousands of e-buses per year. The European market is driven by manufacturers VLD, Mercedes-Benz, Volvo, Solaris, and Scania, all of which have significant delivery contracts with municipalities and other groups around Europe.
Studies taking into account battery life and replacement, infrastructure needs and maintenance requirements have found that e-buses can be very competitive in terms of total cost per passenger mile compared to conventional diesel-powered busses. World Bank studies of bus fleets in Latin America found that cost-competitiveness was often dependent on existing infrastructure and fleet requirements. At the same time, Bloomberg NEF estimates that e-busses will be driven to TCO parity within the next two to three years, and higher up-front costs associated with e-busses will be on par with conventional busses by 2030 at the latest.
With upfront costs ranging anywhere between 570.000 and 1.2 million USD (520.000 – 1.09 million EUR), the purchase of electric busses and fleet transition can be prohibitively expensive, even for the most affluent municipalities. However, before electric buses’ upfront costs reach parity with conventional buses, savings can be made by converting and refurbishing older diesel buses, facilitating the transition without the sometimes-prohibitive upfront costs.
MTB Transit Solutions, a bus repair company based in Canada, proposes changing over municipal busses when scheduled for their engine refurbishments, usually every seven to nine years. They argue that replacing the standard diesel drive train with an electric battery system when these buses were already scheduled for refurbishment closely aligns with municipal budgets, making the transition that much easier. In addition, diesel engine refurbishment typically adds four years to the lifespan of a bus, but MTB finds that switching to electric adds six to eight years of use, compounding savings. MTB currently charges around 500.000 CAD (about 350.000 EUR) for a refurbishment, roughly half the cost of a brand new electric bus and the estimated 40.000-50.000 CAD (28000-35000 EUR) maintenance and fuel cost savings annually.
Gdansk is currently experimenting with a similar retrofitting program for older diesel buses, partnering with a German start up to test implementation of converted battery-buses on municipal routes. Retrofitting older diesel busses is seen to be an ideal solution to move towards a zero-emission fleet in the face of budgetary constraints, and the city hopes to move forward with additional converted buses if the test-vehicle meets performance expectations.
Shenzen is the first city to have an entirely electric public bus fleet with more than 16000 such buses supported by government incentives to close the cost gap between ICE and electric buses. ‘National Electric Vehicle Industry Base’ (in 2011–15 five year plan), which mandates the city of Shenzhen to invest USD 7.9–9.4 billion in the EV industry, constructed and integrated more than 100 large-scale public bus charging stations with bus interchange stations.
While its utilisation in passenger cars does not seem the most viable option, hydrogen does offer a promising opportunity to reduce emissions for long-distance transport. It may be beneficial in the case of buses and heavy-duty freight.
Hydrogen bus technology continues to develop, and transit buses are among the best early adoptions of hydrogen fuel-cell technology. They provide a viable alternative to electric buses for some municipalities. Since hydrogen-powered buses are more energy-dense than conventional batteries, they offer the advantages of longer ranges and shorter refuelling times than traditional buses. For cities with lower temperatures or more hills, hydrogen could be a good alternative, as low temperatures and challenging terrain often saps electric batteries of power quickly, which doesn’t occur with hydrogen.
One particular challenge with hydrogen buses continues to be higher upfront costs and infrastructure costs as opposed to electric buses. Estimates show that for 2020, the total cost of ownership, which includes infrastructure, purchase price, fuel etc., for a hydrogen bus was around 1.9 EUR/km. In contrast, an electric bus TCO is around 1.3 EUR/km, a significant saving for municipalities looking to transition an entire fleet. Infrastructure costs for hydrogen buses, particularly hydrogen production, remain high; however, this is mainly scale-dependent, and prices may decrease through broader adoption.
The EU funded Joint Initiative for hydrogen Vehicles across Europe programme (JIVE and JIVE2) introduces new fleets of fuel cell buses and associated hydrogen refuelling infrastructure in cities and regions across Europe in partnership with the International Association of Public Transport. Their recent knowledge brief analyses best practices drawing on a fictional case study from the JIVE best practice report of 2020. In addition, the H2Bus Europe initiative, centred in the UK, Denmark, and Latvia, aims to introduce low zero-emissions hydrogen busses to participating cities, hoping to achieve the scale required to achieve ideal savings.
London introduced the first fleet of double-decker hydrogen busses, operating 20 zero-emissions busses on the no. 7 line. This comes as part of London’s goal to run a fully zero-emission bus fleet by 2030.
France launched the world’s first hydrogen-powered bus rapid transit system in Pau in 2019.
Konin in Greater Poland region will be the first in Poland to introduce hydrogen cell-powered buses into its fleet. The buses are designed and produced in Poland by a Poznań-based company Solaris, which exports its public vehicles throughout Europe. They will be in use in 2022 and leased for the next four years. The Solaris buses are equipped in a micro-power plant producing electricity from hydrogen, where the only byproducts are steam and heat, and featuring an additional energy storage battery.
Heilbronn, Germany, also opted for the Solaris hydrogen buses. The region plans to generate low-emission hydrogen from wind energy and use it to power its fleet with a zero-emission fuel. Therefore, the overall environmental balance of the whole value chain is close to zero.
In order to meet demand and use requirements of a well functioning bus network when using electric busses, special considerations must be made for charging and range. Busses must be able to charge with relatively little downtime in order to maximise fleet efficiency, something which requires significant power and transmission capabilities. Plug-in chargers are currently limited by wire gauge and weight, however other charging strategies such as opportunity charging and in-motion charging may provide enough energy to maintain a bus fleet with at a high service level.
Opportunity charging is a charging strategy where a vehicle is not only charged overnight at the depot, but at strategically placed charging locations throughout the network as it makes stops during the day. Advancements are being made in this field as more efficient and powerful pantograph chargers are being built, which allow drivers to wirelessly dock at a passenger stop and charge for a short period of time. By adapting busses for overhead pantographic charging, transport authorities can ensure that service is uninterrupted and range requirements are met.
In-motion charging (also called dynamic charging) is a process through which busses charge while in motion. This is typically facilitated through overhead systems, and in the case of busses was adapted from charging systems typically used to deliver electricity to trains and trams. As opposed to opportunity charging this requires no extra time during the day, however flexibility is restricted as busses must follow the set lines where possible. Studies have shown that 20-40% network coverage is capable of providing enough charge while ensuring functionality and flexibility.
Madrid has implemented a series of changes to its bus service, including increasing the number of electric busses and charging stations along bus lines. Beginning in 2016 line no. 76 was equipped with wireless charging stations at each terminus, to test the feasibility of wireless charging with shorter stops. Following this success and later expansion the city transit authority opened the first fully electric bus line to passengers in 2020 and expanded from there, with a complete diesel phase out expected in 2022 following the expected acquisition of over 500 electric busses supported by dynamic and opportunity charging across the city.
Berlin has the largest e-bus fleet in Germany with 137 busses currently in service and a tender for delivery of 90 more in 2022. Berlin is in the midst of increasing non-depot charging options for its fleet, and is placing inverted pantograph charging systems at different stops and terminuses around the city. BVG is partnering with the Technical University of Berlin to continue research into energy efficiency and wireless charging potential throughout the city.