|Renault’s comparison of the carbon footprint of EV and ICE vehicles over production, operation and end of life. The EV footprint (Fluence Z.E.) is shown with both UK and French grid mixes. Click to enlarge.|
Renault recently made public the findings of an internal study, published first in October 2011, detailing and comparing the lifecycle assessments (LCAs) of the battery-electric and two internal combustion engined versions (gasoline and diesel) of the Renault Fluence. The study used the series production versions launched in 2011, with the assumption of operation for 150,000 km (93,205 miles). (Since the BEV version has a shorter range, Renault noted, the way in which the miles are accumulated could differ from that of the ICE vehicles.)
The publication gives the opportunity for an “apples-to-apples” comparison between the environmental impacts of the two types of powertrains: same manufacturer, same model, same boundary conditions. Nevertheless, Renault noted, the study is contrasting a new technology (EVs) with a well-developed one; “environmental progresses are expected in a short term thank to key process improvement and massification of the production.”
Renault also had a panel of experts review the report the ensure full compliance with ISO 14 030 norms related to LCA; the company also published that review report.
The Fluence is a 4-door, 5-seat sedan. Renault assessed the diesel Fluence dCi (1.5L dCi); gasoline Fluence 16V (1.6L); and the battery-electric Fluence Z.E. (22 kWh pack, 70 kW motor).
|Renault Fluence Models|
|Diesel Fluence dCi||Gasoline Fluence 16V||Electric Fluence Z.E.|
|Engines||1.5L dCi (66 kW)||1.6L 16v (81 kW)||70 kW|
|Gearbox||5-speed||5-speed||none||Emission standard||Euro V||Euro V||Euro V|
|Consumption (NEDC)||4.4l/100 km||6.7l/100 km||0.14 kWh/km||Tailpipe CO2 (NEDC)||115 g/km||155 g/km||0|
Renault selected six environmental indicators for the LCA:
Global Warming 100yr Potential (kg CO2 equivalent). Quantifies non-natural increase of greenhouse effect gas concentration (CO2, N2O, CH4, refrigerants...) in the atmosphere and consequently of global warming potential.
Acidification Potential (kg SO2 equivalent). Characterizes the acid substances increase (NOx, SO2...) in lower atmosphere, source of acid rains and forests depletion.
Photochemical Ozone Creation Potential (kg Ethene equivalent). Quantifies the production of pollutant ozone (≠ to ozone layer), the results of the reaction of sunlight on NOx and volatile organic compounds.
Eutrophication Potential (kg Phosphates equivalent). Characterizes the introduction of nutrients (nitrogenous or phosphate compounds per example) providing proliferation of algae.
Abiotic Resource Depletion Potential (kg Sb equivalent). Quantifies ores (steel, aluminum, copper...), water, and non-renewable energies (crude oil, coal...) consumption leading to resources and abiotic depletion.
Primary Energy Demand (MJ) (renewable and non-renewable). Quantifies the quantity of energy (crude oil, coal...) consumption. ￼
Broadly, the LCA found that the principal source of environmental impacts for the combustion engined cars is the use phase; the principal sources of environmental impacts for EVs are production—notably that of the Li-ion battery pack—and the source of electricity.
|Li-ion system production in the LCA|
|The boundaries of the battery system include the production of specific materials for main components of Li-ion cells: cathode, anode, electrolyte and separator.|
|It considers the raw materials extraction and transformation stages, as well as materials transportation and the production of the other components such as: battery case, battery management system, components ensuring battery assembly and electrical connection.|
|Raw materials extraction and transformation were based on data for the average production of lithium carbonate from brine (Chile) and lithium carbonate from spodumene (Australia). Data for manganese is worldwide. The impact of the worldwide extraction for other active materials was modeled by PE International.|
|Components production (electrode rolls, separator rolls, electrolyte) was in Japan, and assembly (cells, modules and pack) in Renault’s Bursa factory (Turkey) on a specific assembly line.|
Although the EV had a much greater impact on emissions during its production phase than the gasoline or diesel versions, the initial deficit was more than overcome during the use phase, even using electricity at the current grid configuration.
For the thermal engines, the impacts in the use phase come from:
- Pollutant emissions (CO2, NOx, HC, CO)
- Two aspects of abiotic depletion: abiotic depletion and pollutant emissions due to the fuel production processes (CO, NOx, SO, VOCs, CO2 emissions).
The company also found that there is a major difference on the global life cycle environmental score depending on the engine technology (gasoline or diesel) used. It also determined that neither engine system—gasoline or diesel—can be considered as better in all categories than the other.
The gasoline model has better results on acidification and eutrophication potentials due to the lower quantities of NOx emitted. The diesel model, on the other hand, due to its lower fuel consumption, significantly reduces its contribution in global warming potential and abiotic depletion (particularly on fossil resources).
For the EV, the vehicle’s production impacts are the same as for ICE vehicles—excluding the drivetrain battery. The production of the drivetrain battery brought some major emissions, affecting negatively the production phase score.
Further, due to the variation in the power grid mix from one country to another, the benefits of the EV varies significantly based on that grid mix. That said, the EV’s carbon footprint remains better than the gasoline and diesel versions in any case.
|Main flows affecting global warming potential of diesel and electric versions all along the life cycle. Click to enlarge.|
The review. On the whole, the review panel concluded that Renault’s report was of a comparable quality level to other existing LCA reports covering the same goal. However, it noted, the fact that the study compared battery-electric to thermal vehicles increased the complexity and the requirements from the ISO standards.
Among the issues the panel identified were:
While Renault’s own production data is detailed, the supply chain data needs to be improved.
The list of emissions from ICE vehicles is not comprehensive (e.g. heavy metals or aromatic hydrocarbons are lacking). The correction factors considered for real-world emissions are relatively optimistic. While the order of magnitude (+15%) for CO2 is only slightly underestimated, the panel said, the real-world factor for pollutants and in particular NOx and PM (which are currently excluded) can be up to five or tenfold in real world usage. This could have been reflected in a higher range for the sensitivity analysis or included in a future revision, when real-world EV efficiency will also be much better known.
The LCI data on battery production is not provided within the report, since they are confidential, and come from a three-year study by Renault.
The treatment of the e-car may be seen unfair from the point of view of the near zero emission at the streets which is an advantage of the e-car even if the energy mix for electricity production is predominantly fossil. It remains unclear if some of the results are “real” or due to artifacts (omission of important processes like emissions from tailing disposal in metal ore mining) in background data. Therefore, several conclusions are not in line with the results, or might be based on artifacts from omissions in background data.—Critical Review Report Fluence and Fluence Z.E.