Guest article: A golden decade for buses

Despite a drop in passenger numbers in 2020 due to Covid-19, there are many reasons to believe that the next decade will be a golden age for buses, especially in urban transport. Building light rail networks only offers benefits for 2030 and beyond, due to the lengthy planning involved. As a result, transport companies are already taking action to accelerate the shift to new forms of transport which has long been overdue. Hamburger Hochbahn currently operates 1,500 buses and is targeting 2,500 to 3,000 for 2030, almost twice the current fleet.

More funds

Significant increases in regional funds for expanding bus fleets appear to be possible. Gertrud Sahler, head of the transport department of the Federal Ministry of the Environment, has earmarked 650 million euros for 1,500 electric buses by 2023, at which point her ministry will no longer provide support. This will be taken over centrally at federal level, making it easier to concentrate funds. However, this sum likely falls far short of what is needed to finance the shift to electric public transport. State Secretary Dr. Tamara Zieschang of the Federal Ministry of Transport has therefore raised the prospect of a further 620 million euros. It should be noted however that future funding guidelines also include fuel cell and RNG buses. Much bigger plans are being laid at EU level, where around 8.5 billion euros have already been earmarked to fund 63 electromobility projects. By comparison however, Germany as the EU’s largest economy is spending far too little on electric buses.

With buses, one has to “think big“

Daniela Kluckert, a member of German parliament and deputy chair of the transport committee, says “with buses, one has to think big .“ Public transport needs financial support, including smaller regional companies, which currently are having particular difficulty obtaining funds. Despite increasing attention being paid to bus transport, electrification will continue to be a “laborious process“, predicts Prof. Henning Kagermann, chairman of the steering committee Nationale Plattform Zukunft der Mobilität (NPM). “There is no escaping electromobility,” says Kagermann. “Even though I am open to alternative technologies.“ Planning them takes too long. “Many alternatives will not be available until 2030”, he adds. If one looks at the cost of hydrogen filling stations, between one and two million euros, and the cost of hydrogen fuel, the same then applies to fuel cell technology. Driverless buses will not be on the streets for “at least another 15 years.“

Patience will be rewarded

Time is becoming an increasingly important factor where the electrification of public transport is concerned. Procuring electric buses is difficult, applying for funding is laborious, and in many cases delivery times range from nine to twelve months. And that is not all. Obtaining approval for the necessary infrastructure and setting it up is also time-consuming. Installing a 110 kV substation can easily take four to four-and-a-half years, and fast-charging points along bus routes generally take two to three years. Installing a fuel cell infrastructure requires even longer-term planning, i.e. more than four-and-a-half years. The net costs are huge: about 420,000 to 650,000 euros per electric bus / articulated bus (prior to funding), 120,000 to 250,000 euros for a fast-charging point including a substation, 20,000 euros for a charger at the bus depot, 10,000 to 100,000 euros on the workshop for every bus (e.g. roof workplaces), 40,000 to 80,000 euros for training and retraining employees, and 50,000 to 150,000 euros for an interchangeable battery after every six to ten years of electric bus operations.

A challenge for the private sector too

With 2019/1161 EU, better known as the Clean Vehicle Directive (CVD), the EU is putting pressure on European transport companies to replace their fleets with low-emissions or zero-emissions vehicles. The directive is required to become German law by 2 August 2021. From then on procurement quotas will apply in Germany as follows: 45 % of buses purchased by 31 December 2025 must be low-emissions vehicles, of which at least half must be zero-emissions. From 1 January 2026 to 31 December 2030, 65 % of vehicles must be low-emissions, of which at least half must be zero-emissions. Unless changes are made to current funding practices, it is already foreseeable that many small and medium-sized bus companies are unlikely to receive 80 % funding from the Federal Ministry of the Environment for extra spending on electric buses. On the one hand, funds are often exhausted by municipal transport companies making large applications. On the other hand, funding applications must cover at least six buses. What is more, the application procedure is extremely complicated and a considerable challenge, particularly for SMEs. Thus a lot of bus companies will need to look for alternatives. One solution could be to convert older diesel buses to electric. There are already some companies marketing this option. Methods vary greatly, however. e-troFit GmbH, a firm in Ingolstadt and a wholly-owned subsidiary of in-tech, a tech company from Garching, is aiming to partner with certified workshops, whose employees are trained to carry out conversions. One advantage is that the workshops will usually be in places where e-troFit customers operate their buses, so that there is always a specialist team available to maintain the high-voltage systems. Another interesting example is CM Fluids, which converts diesel buses to electrically powered RNG buses. This method exploits the output from biogas plants, many of which are now barely profitable, as electricity from photovoltaics and wind power is becoming increasingly cheaper. As a result, they are looking for new markets and could easily supply Germany’s entire bus fleet with RNG.

Will coaches join the shift to electric?

The plans of bus and battery manufacturers go beyond public transport. Already, many battery cells can be charged at 0.8 C or above, which achieves an 80 % charge in one hour, or 70 % in 45 minutes, equivalent to the legal rest period required for drivers after four-and-a-half hours at the wheel. Other high-performance batteries with a capacity of up to 300 kWh could be on the market within a few years. They can be charged at higher C-rates, enabling batteries to be recharged over multiple breaks of only a few minutes. That way, the driver’s legally required rest period could be divided into 15-minute breaks.

Naturally, charging technology is moving forward apace. Thus a CCS initiative called CharIN, a group comprising Audi, BMW, Daimler, Mennekes, Opel, Phoenix Contact, Porsche, TÜV SÜD and VW, part of the High Power Commercial Vehicle Charging Task Force (HPCVC), is currently working on high-performance charging systems for electric utility vehicles with a charging capacity of 1 to 3 MW.

One important issue is the cooling of NMC battery cells. They function best at around 25°C, at which temperature after 360 full charging cycles, i.e. one year of charging at the bus depot, their maximum capacity (SOC) is still more than 98 %. At slightly higher temperatures (35°C) the SOC drops to 95 %. Thus, ambient temperatures have a decisive impact on vehicle range.

Supplying the energy is not a problem

Nowadays, the money required for a medium-sized fleet of 115 Euro 6 rated buses for public transport is around 35 million euros, including for 80 articulated buses. With 80 % government funding, the same number of electric buses would cost approximately 42.4 million euros. But that is by no means all. Batteries need replacing after six to ten years, which by today’s calculations will cost around 13.75 million euros. 30 extra buses, including 20 articulated buses, will be needed in order to service bus routes alongside shorter-range electric buses, incurring an additional 10.96 million euros. Other costs include charging points, mains connections and substations (approx. 15 million euros), as well as modernising and expanding the bus depot and workshops (approx. 5 million euros). Altogether, converting a diesel bus fleet to an equivalent electric fleet costs around 87.11 million euros, a multiple of 2.5.

There is some good news however. For a fully electric fleet of close to 1,800 buses, in Hamburg for instance, the total energy consumption of all the bus depots combined would be around 132 GWh per year. For a Germany-wide public transport fleet of approximately 40,000 electric vehicles consumption would be around 2.5 TWh. By comparison, in 2020 Germany produced 489 TWh of electricity, of which more than 247 TWh (50.5 %) came from renewable sources. Once the necessary infrastructure exists therefore, supplying the energy will not be a problem.

Cologne – a practical example

In practice, do these vehicles really work? KVB in Köln, which since the end of 2016 has been operating eight electric articulated buses with fast-charging LFP batteries on its 133 route, offers data that can answer that question. After three years of uninterrupted service, battery capacity now ranges from 91.8 % to 93.4 %. On average the vehicles have forfeited 7.3 % battery capacity (11.3 kWh), a median equivalent of around 2.4 % per year. After three years, vehicle range has shrunk by an average of 4.46 km, which is not really a major issue. These 450 kW buses can be fast-charged almost to capacity at charging masts at random intervals within twelve minutes. In the future, annual drops in capacity will mean that in seven to eight years time at the earliest, the capacity of the electric articulated buses will fall to 80 % – a critical point for deciding whether retaining the original battery still makes economic sense. Now that the bus manufacturer and the operator have learned their first lessons, vehicle availability is increasing too. Up until the end of 2018 the availability rate of buses 1 to 8 rose to 84 %, while availability of the newly acquired ninth bus has reached 96 to 97 %, on a par with diesel buses. Over the years economy has improved too. The highest consumption figure measured to date was 2.62 kWh, in traffic, and below -10°C in February 2018. The previous high was 3.17 kWh a year earlier. In summer, with the air-conditioning on and in traffic, the maximum consumption measured was 1.7 kWh, or 1.5 kWh without air-conditioning. The extra energy expended on cooling through air-conditioning is therefore negligible. Over the course of 2021 a further 53 buses from VDL will be put into service in Cologne. The state of North Rhine-Westphalia is funding 60 % and the Federal Ministry of the Environment 20 % of the extra cost of electric over diesel vehicles. This new generation of buses will average 0.3 to 0.4 kWh less electricity per kilometre, which naturally will significantly improve their range.