What about battery production? It’s one of the most popular criticisms of the green halo surrounding battery-electric vehicles, and one that’s widely circulated in anti-EV circles. Battery production, it is argued, requires the mining, transportation and processing of minerals which puts EVs at an environmental disadvantage compared to ICE vehicles. Needless to say, quantifying the impacts of ICE and electric drivetrain production is extremely difficult, due to the complexity and global supply chains required to produce both (not to mention the inherent difficulty of quantifying environmental impacts). But a study by the Swiss Federal Laboratories for Materials Science and Technology [via Green Car Congress] took on just that question, and indicates that
the impact of a Li-ion battery used in BEVs for transport service is relatively small. In contrast, it is the operation phase that remains the dominant contributor to the environmental burden caused by transport service as long as the electricity for the BEV is not produced by renewable hydropower.
Impacts for the study are measured in Global Warming Potential (GWP), and Cumulative Energy Demand (CED), which were
chosen for their broad acceptance and relevance in decision making.
Abiotic depletion potential (ADP) was also used to track potential impacts on mineral resource stocks, and Ecoindicator 99 was used to measure
(toxic) effects on human health and ecosystems, as well as damage to resource quality.
PM10, SO2, and NOx emissions are also measured and compared to complete the environmental impact as part of the overall Life Cycle Assesment (LCA). ICE and Battery-Electric Vehicles (BEV) were modeled as follows:
A new efficient gasoline car (Euro 5 standard) was chosen as a basis for comparison. This ICEV consumes 5.2 L of gasoline per 100 km in the NEDC, resulting in a direct emission of 0.12 kg CO2 per km. The car chosen was representative of neither the European fleet nor the fleet of new cars sold in Europe in 2009: 51.4% of the latter consists of diesel fuel cars with an average fuel consumption of 5.7 L/100 km diesel or 6.6 L/100 km gasoline (calculated from CO2 emissions reported in ref). However, the ICEV was chosen to represent a technological level similar to that of the BEV.
The key finding:
The Li-ion battery plays a minor role regarding the environmental burdens of E-mobility irrespective of the impact assessment method used. Transport services with an ICEV cause higher environmental burdens than with a BEV (ADP, + 37.47% or 261 kg antimony equivalents; GWP, + 55.3% or 37,700 kg CO2 equivalents; CED, +23.5% or 593,000 MJ-equivalents; EI99 H/A, +61.6% or 2530 points). The share of the total environmental impact of E-mobility caused by the battery is between 7 (CED) and 15% (EI99 H/A). Analysis with EI99 H/A showed a relative share of E-mobility caused by the battery that is twice as high as analysis with the other impact assessment methods, and this is mainly at the expense of the operation phase.
Though very different than the NiMH chemistry used in most hybrids, and other cobalt or nickel-based Lithium-ion chemistries, the lithium-manganese-based chemistry modeled for this study uses very little actual lithium (0.007 kg per kg Li-ion battery).
In addition, the processes used to extract lithium from brines are very simple and have a low energy demand. Although lithium occurs in average concentrations lower than 0.01% in the Earth’s crust and hence can be considered to be a geochemically scarce metal, assessment with ADP does not result in a high impact for the lithium components. Li2CO3, the base material for the cathode active material and the lithium salt have an impact of only 1.9%. Compared to other components, for example, Mn2O3 (4.4%), copper (5.3%) or aluminum (15.1%), the abiotic depletion of lithium resources does not seem to be critical. However, these results are valid only as long as Li2CO3 is produced from brines. If the lithium components were based on spodumene, a silicate of lithium and aluminum, the extraction of the lithium would require a considerable amount of process energy… The major contributors to the environmental burden for the production of the battery, regardless of the impact assessment method used, are metal supply and process energy.
Of course, this finding is limited to a certain chemistry of lithium-ion battery, made under certain circumstances, and measured using imperfect (though widely-accepted) standards. Still, it’s something to think about the next time someone argues that EV batteries do more environmental harm than good. The major limitation of EVs, it seems, continues to be the fact that most electricity is generated from highly dirty sources, which hurts the EV’s operational efficiency advantages.