If electromobility is the future, it will also result in vast amounts of disused batteries. With its Second Life Batteries project, Vattenfall is testing the secondary use of e-mobile batteries to ensure the quality of the public power supply.

The challenge: Second life for used e-mobility batteries

A traction battery that has been in an electric vehicle for several years may no longer provide the expected range. But it still has a life expectancy of up to 10 additional years.

An optimal second battery life would be the use as a buffer battery for the power supply. Battery storage has been used for some time to compensate for short-term frequency fluctuations with primary control energy and thus to keep the grid frequency stable. Used drive batteries of electric cars are well suited for this task: they represent an environmentally friendly solution also from the point of view that there are no established recycling processes for such old batteries yet.

Second Life Batteries: a resource-saving way to address two problem areas

On the site of the Port of Hamburg, Vattenfall is demonstrating a novel approach to linking mobility with energy supply. To understand this, one needs to know an important aspect about European power supply:

The whole grid works with a mains frequency of 50 Hz. This frequency needs to be very constant and must only deviate within a limited range (49.8 to 50.2 Hz). This will ensure perfect functioning of engines, machines and other electric devices.

The network operators are obliged to provide a consistent network frequency and use relatively accurate forecasts to ensure this quality criterion. However, short-term fluctuations are a challenge and are increasingly compensated by battery storage.

In the Port of Hamburg, Vattenfall commissioned such a storage facility in autumn 2016. It has a capacity of 2 MW and a storage capacity of around 2.8 MWh. The special thing about it: only discarded battery modules from electric vehicles are used, thereby giving them a second life.

To realize the Second Life Batteries project, Vattenfall is working with three project partners: BMW supplies, controls and integrates batteries from its Active-e and i3 models. Bosch takes care of system development and integration of the batteries into the overall system. Vattenfall has provided the foundation and grid connection and is responsible for the operation of the facility.

The battery will be marketed via a new platform of Vattenfall Energy Trading GmbH. Within this pool there is a fully automatic dispatch, ie an internal compensation of the interconnected battery services. In addition, Vattenfall carries out an automated charge management for the connected batteries. Thus, it is ensured that we always provide the system operator with the agreed amount of control energy and make maximum use of the total storage capacity.

Potential: pilot project for a new business model

Above all, the Second Life Battery project serves to gain practical experience. Initial test runs with two smaller storage facilities have already been made in the Hamburg Hafen City since 2015.

The project is initially scheduled for a period of about 10 years. It is one of a few comparable projects of this kind worldwide and gives an insight into a future that has just begun. There are still relatively few traction batteries that are looking for a meaningful secondary application. But the picture will change drastically once electromobility has become a mass phenomenon

The project partners expect the project to provide concrete insights into the technical design of a battery storage system that uses recycled batteries and see it as an important area of application for the future.

As of September 2019

Battery storage
in Numbers

Battery modules installed
Electric vehicles were equipped with it
Megawatt hours of storage capacity

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