Cologne’s public transport company KVB (Kölner Verkehrs-Betriebe), RheinEnergie and Ford have officially put the innovative charging infrastructure of the MuLI project into operation in Bocklemünd. The MuLI project – Multimodal Charging Module Integration (Multimodale Lademodul-Integration) – harnesses, for example, the braking energy of the city’s rail system to charge the KVB’s battery-powered buses and, at the same time, vehicles with electric drives.

The charging infrastructure consists of a charging station, a charging pole for electric buses and two charging columns with two charging points each for electric vehicles. The charging station itself consists of a battery room and a medium-voltage circuit room. The charging pole is located in the area of the KVB’s “Bocklemünd” stop, where the tram lines 3 and 4 as well as the bus lines 126, 143 and 145 make a stop. The charging points for electric vehicles are located on the ground floor of the directly adjacent P&R facility.

In practice, the energy that is released during the braking process of the city trains is converted into electricity (recuperation). This electricity is stored in six battery stacks at the charging station and then released for charging electric buses and cars. The intermediate storage in batteries avoids such things as voltage fluctuations. These would occur if road vehicles were being charged in a fast-charging process and a city train were to arrive at the same time. Since the KVB uses green electricity from RheinEnergie to operate the city rail system, the electricity recovered through recuperation is also green electricity.

The project partners are contributing their specific experience to the MuLI project. For example, KVB has had experience with electrically powered buses on line 133 since 2016 and will convert its entire bus operations to alternative drives by 2030. In addition, the KVB has an extensive infrastructure for the supply of electricity for its light rail network. Three battery-powered articulated buses were procured for the MuLI project, which will be deployed primarily on bus line 126 (Bocklemünd – Chorweiler) but can also operate on the other electric bus lines.

Kurt-Christoph von Knobelsdorff, Managing Director of NOW GmbH: “Electrification is the key for achieving the climate protection goals in the transport sector and thus also for buses in public transport. But at least as important as the vehicles themselves is the corresponding charging infrastructure. The MuLI project simultaneously combines several core topics of charging infrastructure development in an innovative manner, namely: the use of infrastructure already in place, smart grids and storage solutions. It thus contributes to making urgently needed progress in decarbonisation quickly. NOW is very proud to have been able to support this project for the German government.”

Stefanie Haaks, Chairperson of the Board of KVB: “As KVB, we are pioneers in the field of climate and environmental protection in Cologne. That is why we are delighted to contribute our expertise towards the development of innovative charging infrastructures in order to repurpose, so to speak, green electricity used for other means of transport through recuperation and clever storage options. Such ingenious solutions could also find further applications with the experience gained from the MuLI project.”


RheinEnergie is already a partner of the KVB on line 133. Here, the company has established and operates the charging infrastructure, just as it is currently undertaking at various other terminal stops in the city. In the MuLI project, this includes, in particular, the battery room and the medium-voltage circuit room, where the energy storage, energy conversion and the entire technical management take place.

Dr Dieter Steinkamp, Board Chairman of RheinEnergie: “Electric mobility plays an important role in climate protection. With flexible storage solutions such as MuLI, we can drive the expansion of the required charging infrastructure in Cologne even faster by drawing on KVB’s existing power grid. The technology also supports us in balancing voltage fluctuations in the electrical grids, such as those caused by the generation of volatile renewable energy.”

In contrast to the charging infrastructure for KVB’s bus operations to date, the MuLI project uses car batteries living a “second life” for storage. To enable this, the Ford-Werke has put together a storage system consisting of six units each with 48 battery modules (each with 20 individual cells). The storage units each weigh 700 kilograms, are 2.20 metres high, 1.20 metres wide, 0.60 metres deep and boast a total installed storage capacity of around 300 kilowatt-hours (kWh). They are embedded in an energy management system.

“Resource conservation and ‘second life’ are on everyone’s lips these days. With this model project, we were able to investigate the secondary recycling of high-voltage batteries, a topic that is becoming increasingly important with the rise of electric mobility,” emphasises Gunnar Herrmann, Chairman of the Management Board of Ford-Werke GmbH. “With our batteries, it was possible to design a local energy storage system that is able to store the recuperated energy of the light rail vehicles as they enter a station and brake in the process, while simultaneously being used to charge vehicles at the charging stations. This is a viable way to achieve secondary use of batteries from electric vehicles.”

KVB, RheinEnergie and Ford have worked together since 2012 in the colognE-mobile project and since 2018 in a project on the geofencing of electric vans.

The MuLI project partners are supported by the engineering firm Ingenieurbüro Fehringer (Dortmund), which has been active in the fields of electrical engineering for over 25 years. The specialists make use of a battery laboratory and work with batteries in all the necessary sub-topics.


The aim is to demonstrate an innovative charging system

The aim of the MuLI project is to demonstrate a charging system with integrated charging modules for different vehicle classes. The core of the system is designed for recharging battery buses. At the same time, the multimodal charging system is connected to different voltage levels of alternating and direct current (10 kV AC, railway DC). The project is intended to demonstrate the technical feasibility.

Moreover, a scalable storage solution was also realised. The basis for the energy storage units is comprised of high-voltage vehicle batteries whose storage capacity is no longer sufficient for mobile applications, but which can nevertheless still be utilised in stationary applications in a “second life” deployment. These batteries are used for grid stabilisation, minimising power consumption and optionally as a balancing power reserve for local electricity grids. This can reduce the costs of both mobile applications (e.g., electric cars) and stationary storage. The MuLI project is testing the suitability of using such batteries in a system network.


Federal Ministry of Transport supports MuLI project with 1.87 million euros in funding

The project budget totals around six million euros. This includes funding of 1.87 million euros from the Federal Ministry of Transport and Digital Infrastructure (BMVI) through the “Local Electric Mobility” (“Elektromobilität vor Ort”) funding guideline.

From this total funding volume, Cologne’s KVB transport authority will receive around 700,000 euros for the project management and the purchase of three electric buses. RheinEnergie will receive around 980,000 euros for the construction and connection of the charging infrastructure. And Ford-Werke will receive around 195,000 euros for the construction of the energy storage system.

NOW GmbH (National Organisation Hydrogen and Fuel Cell Technology) and the Project Management Organisation PtJ (Projektträger Jülich) from the Research Centre Jülich (“Forschungszentrum Jülich”) are also involved in the funding process.


Total potential is greater than share of traffic attributable to public transport

In Cologne, total bus traffic – that of local passenger, long-distance and charter services – accounts for only three to six percent of all traffic in the city area (without or with the addition of motorway traffic, respectively).

The total potential in Cologne is immense: Currently, a total of about 570,000 motor vehicles are registered, including 500,000 passenger cars alone. The share of electric cars is still low, with less than 6,000 hybrids and about 2,500 pure electric cars, but this number is set to grow steadily. The situation is similar for car-sharing vehicles in Cologne. Of the approximately 1,250 vehicles, only about five percent are electric vehicles. But here, too, significant growth rates must be expected. In a study for the Cologne Chamber of Commerce and Industry, it was determined that approximately 150,000 CEP consignments are distributed daily in Cologne by around 1,000 trucks, mostly vehicles up to 3.5 tonnes, which make approximately 80,000 stops in the process. Public transport and the local energy supplier can serve as a nucleus for the spread and establishment of electric mobility if they offer technical solutions for the development of the charging infrastructure.


E-mobility hub will provide innovation insights

One of the main innovative features of the MuLI project is its multimodal character, which bundles the charging technology for different vehicle classes – with medium voltage of alternating current and direct current of the city rail – at a single station. The project is also innovative as car batteries are used as intermediate storage in a “second life” system.

With MuLI, the project partners are gaining knowledge about the development and configuration of such a charging infrastructure. Later, the experiences gained can be incorporated into the further development of such infrastructure.

An e-mobility hub was created at the aforementioned terminal stop, where other vehicle classes, such as vans used by CEP services and car-sharing cars, can be charged in addition to the electric buses deployed on line 126. Their operators can therefore also accumulate experience and incorporate it into their e-mobility strategies.

As a result of the MuLI project, further e-mobility hubs can be established and become a building block in the charging infrastructure landscape in Cologne. A combination with mobility stations, in which sharing offers are bundled, is conceivable. MuLI is thus equally linked to the vision of rolling out electric mobility over a wide area and advancing the necessary mobility transition.


MuLI meets sustainability criteria

The MuLI project fulfils the requirements of sustainability across a range of dimensions. The establishment of charging infrastructure in the area makes the conversion of road traffic to electric drives possible. This serves climate and environmental protection as long as green electricity is used in the project. In particular, the conversion of the large passenger car fleet is necessary to reduce emissions of carbon dioxide (CO2) and nitrogen oxides (NOx). The conversion of the KVB bus operation to alternative drives also contributes to climate and environmental protection goals of the city of Cologne. With charging infrastructure along the lines of MuLI, building part of the required charging infrastructure is being made possible.

The use of car batteries in secondary utilisation also makes ecological sense. In this way, the raw materials contained in the batteries will not already need to be recycled after their mobile use in the car comes to an end. Through their “second life”, the investment costs of the batteries will be offset by a prolonged useful life. In principle, the acquisition costs for car owners will be reduced or there will be opportunities for resale. This equates to economic sustainability. In addition, time is gained to improve recycling processes and thus further minimise the ecological footprint.

The development of charging infrastructure in rural areas requires the expansion of the general municipal electricity grid, which is designed to meet current household needs. This will involve a significant financial and operational effort. Therefore, using the existing energy technology assets of the city railway, which can be linked into mobility hubs according to the blueprint provided by the MuLI charging infrastructure, is economically sustainable. It increases the value of the city’s light rail infrastructure and avoids some of the further development costs.

Publicly accessible charging infrastructure, such as that in the Bocklemünd P&R facility, also provides road users with the opportunity to recharge their cars, even if they do not have the possibility to do so in the vicinity of their homes. Especially in multi-storey housing, where tenants cannot simply install so-called wallboxes, this makes it possible to switch modes of transport without significant additional costs. This therefore addresses an aspect of social sustainability.

Further information can be found (in German) at:

Image source: Christoph Seelbach