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The energy sector is undergoing rapid transformation. Public authorities are deploying electric buses and the rooftops of many households host solar panels. The transition to electromobility and renewable production of electricity is on the move. This evolution is necessary to decarbonize our economy, but we should not forget it will also increase battery production.

Batteries come at an environmental cost which, if left unmanaged, can partly offset the gains of moving away from fossil fuels. We must keep the environmental impacts of batteries as low as possible through a renewable and efficient manufacturing process, the use of recycled raw materials, circular design, and high-quality recycling.

At the end of the road, reducing the environmental footprint of batteries will come down to ensuring they last as long as possible, and giving them a second life to store solar power in stationary facilities is a prime way of doing so.

Life’s too short

EVs have a 20-year expected lifetime but their batteries might not last as long. Even as technology continuously improves, the capacity of EV batteries declines over time. When a battery reaches 80% of its initial state of health (SoH) – an important parameter representing the wellbeing of the device – it is considered unfit for EV use. Today, manufacturers often guarantee batteries will take at least eight years to reach that level – much earlier than the lifetime of the vehicle itself.

At this stage, there are two main options. One is to send the battery to a recycling facility where only a few metals will be recycled, in an energy-intensive process. The second, and preferred option, is to give the device a second life.

What kind of new life can a used EV battery have? There are two alternatives. It can be reused for another less-consuming vehicle or be repurposed for a less-demanding application. For instance, a repurposed battery can store electricity in buildings. Each reused or repurposed battery avoids producing a brand-new one – with all the environmental impacts that implies.

We have to be careful, however: a large share of repurposed batteries today come from industrial waste or discarded devices that did not pass their quality tests. In this case, the environmental gains are minimal as the battery is, de facto, being repurposed for its first “real” life. However, we can expect that, with a increasing amount of EV batteries reaching the end of their first life, there is higher potential for “true” second-life batteries.

Bumpy road

Even if the potential is high, repurposing a battery is still a tricky process, at least for use on a larger scale. The reasons for this are multiple.

Firstly, some EV battery manufacturers prefer recycling. They claim recycling products right after their end of life in EVs is more cost-effective than giving them a second purpose, as the latter option would delay the recycling process. For some manufacturers, this would mean that precious materials are kept hostage in a repurposed product instead of being reused in valuable new vehicle batteries.

Secondly, technical issues occur when used batteries “speak different languages.” The brain of a battery – the battery management system – can use different communication protocols and datasets across differing devices. Take the SoH of a battery: unfortunately, no clear definition currently exists for this parameter. Since battery degradation is a combination of capacity and power fade, efficiency reduction and rise in negative incidents etc, any combination of these parameters can be considered a factor in the SoH of a device. The lack of a common language makes repurposing processes difficult to upscale. Since the calculation of SoH differs across brands, creating common processes that could work for different cars is challenging and, therefore, more expensive.

Thirdly, there is no obligation to repurpose batteries after their first life, or even to test whether they would be suitable for a second life. This leaves the choice of repurposing batteries to the market players, which are not obliged to focus on the environmental impact of their products.

Afterlife pit-stop

Luckily, there are solutions to unlock the potential of EV second-life batteries for use in stationary storage. To make repurposing more sustainable and profitable, it is necessary to upscale the process. A good option would be to mandate tests for EV batteries that reach the end of their first life, to see whether they are suitable for reuse or repurposing before being sent to a recycling facility.

Standardized battery management system formats, a common definition of SoH, and common test methods could also ease the technical barriers repurposing operators face. But technical solutions are not enough: reuse and repurposing will not prevent many batteries from being recycled, and thus cheated out of their second life. We need a mindset shift among EV battery manufacturers.

A transition towards cleaner mobility, and energy systems coupled with a repurposed battery, could not only minimize the environmental impact of battery production but also reduce the impact of transport on the environment altogether. Second-life batteries are the next, and only, logical step – but we must act today.

About the author: Rita Tedesco is head of energy transition at the Environmental Coalition on Standards (ECOS). Prior to joining the NGO in 2018, Tedesco worked at Transport & Environment (T&E), Europe’s federation of NGOs campaigning for cleaner transport. She holds a masters degree in international relations from Université libre de Bruxelles.

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