'Spent' lithium-ion batteries from Renault EVs are being given a new lease of life powering boats on the River Sein in Paris. Taken from across the range of Renault Z.E. vehicles, the cells are refurbished and installed into Black Swan leisure boats to allow people to cruise the river in near-silence and with no impact on Paris's air quality.

The programme of reusing Z.E. batteries has come as a result of a partnership between the Sein Alliance and Renault Green Vision. Paris has a committed to having an electric-only river cruise fleet by 2024, and the Black Swan is the latest craft to take to the water as part of this.

Whilst we can hardly call ourselves boat experts, the eight-seat Black Swan cuts a sleek shape which is based on an existing design from Italian boat builders, Tullio Abbate. Typically, such cruisers would be powered by powerful V8s from the likes of Mercury or Volvo Penta with anything up to 380bhp on offer from a 6.0-litre unit. In place of this, the Black Swan has the second life batteries located in watertight containers beneath the passenger seats, and two 27bhp motors. Combined, the batteries and motors weigh 278kg which is less than the V8 setup.

Of course, with only 54bhp on tap the Black Swan isn't going to hit the 50+mph of the V8 versions. But it's a river cruiser and the chances are it'll spend most of its life below 10mph. At these leisurely speeds on the river the Black Swan can cruise for up to two hours and also be charged in two hours.

Giving spent batteries a second life

The common perception among the public is that once a lithium-ion EV battery has lived its first life powering a car, it's junk. But furthermore not only is it junk, it'll spend the rest of time leaching noxious chemicals back into the environment or use significant energy to dismantle it. However, the fact is that lithium is 100 per cent recyclable, and most of the other materials can be reused.

Before a battery ever need get near a recycling plant there's now a burgeoning market in 'second life' usage. Renault has been at the forefront of this, developing what it calls a circular economy by reducing the extraction and use of raw materials by refreshing and reusing existing resources.

EV batteries are often considered spent even with up to 70 per cent of their original capacity remaining. Whilst they may no longer be any good for their intended use they can be broken down, tested and refreshed, and then put to use in all manner of applications. Renault 'second life' batteries are being used in everything from back-up power banks for lifts, to the Smart Fossil Free Island project on Porto Santo, Portugal (you can watch Renault's video here). On Porto Santo the spent Z.E. batteries store energy from the solar and wind farms which can be released into the local grid when there's little wind or sunlight.

Creating the circular economy

Schemes like the Black Swan river cruiser and Smart Fossil Free Island by Renault are just two of the many ways in which car manufacturers are beginning to create a circular economy to extend the practical life of their batteries. Such economies enable manufacturers to actually profit out of the products they created several times over – increasingly important given that in the EU, it is the manufacturer's responsibility to arrange recycling.

In Renault's case, it has found a niche in using its old batteries for powering leisure boats. And if there's money to be made out of it, and it helps clean up Paris's air, then maybe it's not such an in-Sein idea after all.