Efficient diesel engines commonly prevail in bus fleets in China and Germany for a good reason: Looking at the costs of procurement and operation they are still the economically most sensible technology. But also from an environmental perspective diesel engines have noticeably improved. For instance, particle filters have reduced PM 2.5 emissions of Berlin’s bus fleet considerably with a positive effect on ambient air quality.
However, new solutions are required to reduce the climate impact of internal combustion engines. Even highly efficient diesel buses burn fossil fuels and consequently emit greenhouse gases. In China, cities struggle to retrofit the existing diesel bus fleets and consider to directly leapfrog to electric mobility. Whether electric buses are the right solution for municipal governments was at the core of the discussion of the Sino-German Workshop on electric buses organised by the Chinese Research Institute of Highway, the Ministry of Transport and GIZ on August 26th 2015.
First pilot operations show that the battery costs remain to be excessively high, operational reliability remains to be problematic and the space requirement of batteries remains to be substantial. At the same time, coal based energy production currently lowers the greenhouse gas mitigation potential – a problem of e-mobility in general. However, participants agreed that in order to activate the climate protection potential in the mid-term, innovative propulsion technologies, charging infrastructure and a transformation of the energy sector has to start now.
This is why, several pilot projects were initiated by the German and Chinese Government. Even though Germany and China pursue the same goal, the two countries have followed different approaches: On the one hand, the Chinese government and several municipalities have provided substantial subsidies and invested in charging infrastructure, maintenance facilities, depots and large scale trials like no other country. On the other hand, Germany, currently only implements few small-scale research projects – among them Berlin, Hamburg, Muenster and Munich with the objective to evaluate different technologies in detail.
Development status in China
A total of 529.000 public buses -from which 36.500 are electric buses- are operating in Chinese public transport fleets. By 2020 around 200.000 new energy buses are supposed to be integrated in public fleets in China. To reach this aim, Chinese cities are currently testing different charging and propulsion technologies. An overview is given in the table below (click on the table to enlarge):
Experiences of the different pilot cities show a promising operational performance of fast conductive charging solutions, in -motion charged trolley buses that cover a considerable “off-grid-distance” and plug-in hybrid buses. Slow charging and battery-swapping have proven to be problematic due to their long standing time and high space requirements. Inductive charging has not yet found its way into larger scale projects in China.
Operational complications with current trials were controversially discussed during the workshop. Battery attenuation (battery lifetime below expectation), charging facilities (long distances of empty trips to charging stations), unclear responsibilities for battery recycling and currently low operational reliability have been considered crucial issues to be resolved. In addition relative cost efficiency of different propulsion technologies was discussed at the workshop. For now, electric buses can hardly be operated cost-effectively due to the high procurement costs and fast attenuation rate of the battery. Consequently, operators rely on high subsidies.
The next step in China is to facilitate an in-depth evaluation of the trials in terms of the environmental performance, operational processes and cost-benefits.
Germany
Within the scope of the governmental programme “Electric mobility showcase” (“Schaufenster Elektromobiltät“) 29 projects with 171 dieselhybrid buses, 25 electric buses and 12 fuel cell buses are tested regarding their suitability for practical application, energy efficiency, climate and environmental protection potential, cost-benefits and acceptance. Since September 2015, Berlin as a new pilot city has replaced a bus route with 4 electric buses charged by inductive charging technology. It is expected that annually 260 tonnes of CO2 can be saved through the pilot route. Mr. Arkan Ok, Manager for Strategic Product Development at the Berlin transport company shared the electric bus plans of Berlin during the workshop (see presentations below).
The experts from China and Germany agreed that the challenges of vehicle fleet electrification -well known with private cars- can be overcome in bus operations:
- While private vehicles require a large, scattered charging infrastructure, buses are mainly operating on fixed routes.
- Contrary to private vehicles that are parked on average more than 20 hours a day, buses operate the whole day. The impact of a converting a single bus into clean propulsion technology is therefore considerable.
- Given that buses operate mainly in stop-and-go urban traffic they have a high potential to make use of recuperative energy.
Evidently, financial and technical glitches still need to be resolved. Electric buses need to become competitive in terms of their life cycle costs, battery recycling needs to become more efficient, energy density needs to improve and operational procedures need to be adjusted. However, a low-carbon transport sector independent from fossil fuels is not within reach with conventional buses. Sustainable solutions have to be found to increase the competitiveness of electric buses and to eventually transform entire fleets into green, emission free bus operations running on electricity produced by renewable energy.
The Sino-German Cooperation on Low Carbon Transport, implemented by GIZ on behalf of the German Federal Ministry for Environment, is a suitable platform to facilitate an exchange to ensure that electric busses can provide the service we expect but with a lower environmental impact we know.
Contact: [email protected] (Project Manager)
Please find the presentations to download below:
LI Bin, Director, Research Institute of Highway, Ministry of Transport
Arkan Ok, Manager Strategic Product Developement, Berlin Transport Company
YU Gang, General Manager, Shenzhen Bus Group Co., Ltd.
Martin Schmied, Designated Director of Transport Division, German Federal Environmental Agency
ZHAO Lijin, Society of Automotive Engineers of China
Scania Co., Ltd.
Overview of different technologies for e-buses being tested in Chinese cities:
