Renault compares lifecycle footprint of electric v petrol and diesel carsMay 29, 2013
Renault has compared the lifecycle footprint of its Fluence ZE electric car directly against its petrol and diesel equivalents.
Attempts to assess the environmental impact of electrically propelled cars have earned a chequered reputation. The discordant tone was set in 2007, with suggestions that low-tech American SUVs might have a lower lifecycle impact than a Japanese Toyota Prius, due to the extensive industrial processes needed to make high-capacity batteries.
The source for that particular story, a report called, “Dust to Dust: The Energy Cost of New Vehicles from Concept to Disposal”, has since been discredited for building its findings on faulty assumptions. But despite subsequent and better research, there is still plenty of debate about the environmental footprint of battery-electric versus internal combustion. As recently as October 2012, a BBC headline stated: “Electric cars ‘pose environmental threat’”, citing a Norwegian academic study and focusing on the “toxic waste” produced in the manufacture of batteries and electric motors. In turn, EV enthusiasts keen to debunk the findings focused on links with the oil industry among the study’s authors.
Now car manufacturer Renault has ventured into this controversial zone with the release of its own study, circulated internally last year and now available to the public. Uniquely, the company has been able to assess the impact of both EV and conventional car production processes from the inside. And it has even been able to compare apples with apples, given that a single model – its Fluence saloon – is built with battery-electric, petrol and diesel powertrains.
The study concedes that Renault’s “zero-emissions” Fluence electric car has a much bigger impact during its production phase than either its petrol or diesel cousins, but it concludes that the initial deficit is more than overturned during a typical 10-year, 93,000-mile lifecycle and disposal. Renault’s data showed the petrol variant of the Fluence had a markedly worse lifetime impact than the diesel, but that the EV version bettered both – even when charged from a relatively dirty grid such as that found in the UK.
Make no mistake, Renault has a motive to put EVs in a positive light. Together with Nissan, its partner in the Renault-Nissan Alliance, the company has invested billions of euros to take a pioneering role in EV development. And Renault currently has a line up of four “ZE” vehicles to sell: its Twizy urban runabout, Zoe supermini, the Fluence ZE that was the subject of its study, and the Kangoo ZE electric van. A fifth model, a Twingo ZE city car, is due next year.
So to add credence to its research, Renault asked for its methods and conclusions to be vetted by independent experts in lifecycle analysis, and revised its report accordingly through several cycles of correction. And indeed it has published the “Critical Review”, warts and all, alongside its own findings.
It may be no shock that Renault’s report gives its own EV a good report card. But surprisingly, the vetting team suggests that the improvement over diesel and petrol equivalents might even be bigger than Renault suggests, due to some excessive optimism about the two internal-combustion cars. The review cites heavy metal and hydrocarbon pollution from liquid-fuelled cars as areas where Renault might have delved deeper, and notes that ordinary cars create more brake dust, for example, than EVs with regenerative brakes – a factor not considered in the study.
Renault’s report runs to 120 pages and is exceedingly broad in scope and highly detailed – it can be downloaded from www.Renault.com
] along with the critical review [ http://www.renault.com/fr/lists/archivesdocuments/critical-review-fluence-acv.pdf
]. It assesses the impacts of long chains of industrial processes and real-world car usage against a set of six core criteria: global warming potential, depletion of resources, sources of energy, photochemical ozone production, acidification and eutrophication, the final category referring to the output of chemicals likely to harm aquatic ecosystems.
And to add context, Renault also attempts to assess the contribution of personal transport as a proportion of the average European citizen’s overall environmental footprint.
“We have to study all the impacts together to really state whether one vehicle is better than another,” explained Jean-Philippe Hermine, Renault’s vice president for strategic environmental planning. “The two main impacts of a vehicle – of whatever sort – are resource depletion and global warming. Those are the two major impacts the car manufacturing industry has to face. Of course we have an impact on acidification, eutrophication and photochemical ozone. But relative to the whole footprint of a European person, this is less important. That’s why we must talk a lot about CO2 and fuel economy when we talk about the impact of a car.”
One of the important points that Renault makes is that, with EVs still in their infancy, it’s not yet possible to talk about the impact of a typical electric car. The differences between competing EVs are too great for generalisations.
In particular, the choice of battery chemistry has a disproportionate impact on the overall footprint of an EV, even within the broad family of batteries labelled lithium-ion. Chemistries that feature cobalt, such as lithium nickel manganese cobalt oxide (NMC) and lithium nickel cobalt aluminium oxide (NCA), have a much deeper environmental impact than alternatives such as lithium manganese oxide (LMO), according to Renault’s data.
“The impact of the various battery types is very different,” said Philippe Schulz, Renault’s expert leader for environment, energy and raw materials. “When you compare lifecycle analyses, it’s important to understand, what is the chemistry of the battery? This is key to the final result. We decided to use LMO, and one of the explanations is that the environmental impact is the best compared to all other chemistries.”
Even with the least harmful chemistry, the battery in the Fluence ZE still accounts for a huge slug of the car’s impact, according to Schulz.
The battery makes up 274kg of the car’s 1.5-tonne mass, and within the battery’s modular casing only around 55kg is chemically active in the business of storing energy. “The impact of the active materials is very high compared to all of the remaining materials of the car,” Schulz explained. “Between 30% and 50% of the entire car’s footprint [across the different impacts considered] is due to the 55kg of active materials in the battery.”
Future EV batteries will no doubt have higher energy densities and longer lifecycles, helping to ease the weighty impact of their construction. There will also be more opportunities to integrate recycled materials, reclaimed from the first generation of EVs, as Schulz pointed out.
For Renault, the work behind its report is an important stake in the ground – a benchmark from which it can measure any future improvements as it builds the next generation of cars.
“We study lifecycle impact for every vehicle, not only for the EV,” said Schulz. “Our approach is to make every new vehicle better than the previous generation. That is our strategy. That’s why it’s key to manage this properly and to have a large database. So we have a clear roadmap about how to improve something which is already very good.”