Oberhausen drives electrically

Local public transport will play a central role in the mobility concepts of the future. In order to satisfy the increasing mobility needs without negative effects on the environment, even more people need to be motivated to use local public transport.  

Electric buses as a climate-friendly alternative

Urban bus traffic is currently largely determined by diesel vehicles across Germany. In order to become independent of fossil fuels and to reduce nitrogen oxide, fine dust and noise emissions in metropolitan areas, alternatives to diesel vehicles are required. Buses with an emission-free electric drive are such an environmentally friendly alternative.   

"North Rhine-Westphalia needs future-proof mobility concepts," says NRW Transport Minister Michael Groschek. “I am pleased that e-mobility is being networked even more closely with local public transport in Oberhausen. This makes an important contribution to the achievement of local and national climate and environmental protection goals. The necessary knowledge for the future can only be gained through the practical use of such new technologies. "  

Various transport companies are currently gaining experience with electric bus drive technologies. Different e-bus systems and charging systems are used. The vehicle battery is of crucial importance. On the one hand, it serves as an energy store to provide the drive energy, on the other hand, it is able to partially absorb the kinetic energy that occurs during braking and thus make it available for the subsequent acceleration process. 

The Oberhausen model

Verkehrsverbund Rhein-Ruhr (VRR) and STOAG jointly gave the go-ahead for a project last year in which the existing direct voltage infrastructure of the tram is used to charge battery buses while they are in operation. The charging energy is taken on the one hand from the contact line and on the other hand from a substation in which the DC voltage of 750 volts required to operate the tram is generated. The energy transfer takes place conductively by means of a foldable pantograph, which is located on the roof of the buses. Due to the regular recharging during the turning times, the traction batteries in the buses can be dimensioned relatively small and thus weight and cost-saving. Nevertheless, the capacity is designed in such a way that up to three charging cycles can be skipped in the event of unforeseen events. All secondary consumers such as air conditioning and heating systems are also fed by electrical energy. The storage capacity of batteries with cells from manufacturer A 123 is 200 kWh. EKO Energetyka is responsible for the chargers, Schunk supplied the pantographs, and Siemens implemented the infrastructure. 

The Urbino 12 electric buses come from Solaris. With low-floor technology and air conditioning, they correspond to the standard used by STOAG. It is driven by a ZF AVE 130 axle with two asynchronous motors close to the wheel.  

Scheduled traffic starts in October

On October 4th, STOAG starts operating the two inner-city lines 962 and 966 with the two electric buses. Then the 15,6 and 13,3 kilometer long routes will be completely converted from diesel to electric operation. On line 962, charging energy is drawn from the catenary at the break area at Sterkrade station, on line 966 from the Neumarkt substation. The charging processes take place during the turning times and take a maximum of ten minutes. It is not necessary to charge the vehicle while it is parked at the depot at night.  

"By operating two bus routes purely electrically and feeding them with electricity from renewable energy sources," says STOAG Managing Director Peter Klunk, "we are getting a good deal closer to our goal of using the existing infrastructure to achieve emission-free local transport."

Fast charging for cars too

The existing tram infrastructure is also suitable for rapid charging of vehicles from other modes of transport. Energieversorgung Oberhausen AG would like to demonstrate this by setting up fast charging stations for cars, which are also fed from the tram catenary, and show that the fast charging options that are indispensable for the rapid introduction of electric vehicles can be implemented with relatively little effort in cities with existing DC infrastructures. Three quick charging stations for electric cars will go into operation in November 2015.  

“With these three projects in Oberhausen, the high relevance of existing direct voltage infrastructures of local public transport for the cost-effective implementation of urgently needed fast charging options for electric buses in regular service and battery vehicles of other modes of transport is made clear,” summarizes Professor Dr.-Ing. Adolf Müller-Hellmann from RWTH Aachen who oversees the entire project.  

Costs still high

With costs of around 500.000 euros for an electric bus, it is still more than twice as expensive as a standard bus today. "The batteries are currently the most expensive element in the bus, but the costs are falling," explains STOAG managing director Werner Overkamp. The energy efficiency of electric buses is significantly higher than that of diesel buses, and the maintenance effort due to the lack of combustion processes at high temperatures is probably lower. “By using our existing tram infrastructure,” says Werner Overkamp, ​​“there are no costly costs for the charging system. The high-performance charger for regulating the charging current of the batteries is placed in the substation so that no additional building has to be built to accommodate the components for rapid charging of the batteries ”.

Nevertheless, projects like the one in Oberhausen cannot be handled by the transport companies alone. The Verkehrsverbund Rhein-Ruhr has therefore accompanied and supported this commitment of STOAG from the start. "In order to help make energy-efficient, alternative drive systems suitable for everyday use, the VRR is happy to support this project as a demonstration project," explains VRR board spokesman Martin Husmann.  

STOAG as a partner in the ELIPTIC project

STOAG is also proud to be a partner in the EU project ELIPTIC with the Oberhausen model project. ELIPTIC stands for "Electrification of public transport in cities". It is intended to further research the possibilities of electrifying public transport in combination with the existing transport and energy infrastructure in order to develop business models for cities, municipalities, but also for transport companies. In particular, STOAG brings the findings from its e-mobility project to the ELIPTIC project and, with the support of the Institute for Power Electronics and Electrical Drives at RWTH Aachen University, is developing an expansion concept for electromobility in Oberhausen.