Study Finds Environmental Impact of Li-ion Battery for BEVs is Relatively Small; The Operation Phase is the Dominant Contributor to Environmental Burden

Notter
Environmental burden of a gasoline-fueled ICEV relative to that of a BEV (100%) assessed by four different methods: abiotic depletion potential (ADP), nonrenewable cumulated energy demand (CED), global warming potential (GWP), and Ecoindicator 99 H/A (EI99 H/A). Credit; ACS, Notter et al. Click to enlarge.

A team from the Swiss Federal Laboratories for Materials Science and Technology (Empa) compiled a detailed lifecycle inventory of a Li-ion battery and produced a rough lifecycle analysis (LCA) of battery-electric vehicle mobility. Their study, published in the ACS journal Environmental Science & Technology, showed that the environmental burdens of mobility are dominated by the operation phase regardless of whether a gasoline-fueled ICEV or a European electricity-fueled BEV is used.

Compared to a reference internal combustion engine vehicle (ICEV), use of a BEV in transport results in lower environmental burdens as assessed by four different methods, they found. However, the PM10, NOx and SO2 emissions caused by E-mobility were higher compared to mobility with an ICEV.

The share of the total environmental impact of E-mobility caused by the battery (measured in Ecoindicator 99 points) is 15%. The impact caused by the extraction of lithium for the components of the Li-ion battery is less than 2.3% (Ecoindicator 99 points). The major contributor to the environmental burden caused by the battery is the supply of copper and aluminum for the production of the anode and the cathode, plus the required cables or the battery management system.

The researchers modeled a LiMn2O4 battery, assuming that manganese will in the near future be substituted for the nickel and cobalt commonly used currently. They also performed calculations on different cathode materials containing nickel, cobalt or iron-phosphate in order to check the sensitivity of the results.

The electric vehicle studied was comparable to a Volkswagen Golf in size and power with a range of around 200 km (124 miles) per charge with an assumed lifetime of 150,000 km (93,000 miles). They assumed that 14.1 kWh of electric energy is needed per 100 km to propel a Golf-class vehicle with an overall efficiency of 80% (including charging losses and recuperation gains) in a standard driving cycle (New European Driving Cycle, NEDC). Heating, cooling, and electronic devices consume 2.9 kWh/100 km. The BEV thus required a total of 17 kWh/100 km.

They chose the average electricity production mix (UCTE) in Europe for the operation of the BEVs in agreement with the criteria used in the rest of their study and in the ecoinvent database. The environmental burden for the operation of BEV depends mainly on the choice of electricity production.

The ICEV reference vehicle was a new efficient gasoline car (Euro 5 standard) consuming 5.2 L/100km (45 mpg US) in the NEDC, resulting in a direct emission of 0.12 kg CO2 per km.

They expressed the environmental burdens as global warming potential (GWP) applying a time frame of 100 years; the cumulative energy demand (CED) of which only the nonrenewable (fossil fuel and nuclear) are disclosed; and the Ecoindicator 99 using the hierarchic perspective and an average weighting (EI99 H/A). They indicated resource depletion as abiotic depletion potential (ADP), one of the impact categories in the CML method. They also presented cumulative particulate matter (PM10), SO2, and NOx emissions.

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 EI99H/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.

...PM10-, NOx-, and SO2-emissions caused by E-mobility (PM10 100%, 16.2 kg; NOx 100%, 49.5 kg; SO2 100%, 83.7 kg) are higher compared to mobility with an ICEV (PM10 79.0%, 12.8 kg; NOx 87.9%, 43.5 kg; SO2 74.7%, 62.5 kg; Supporting Information Figure S1 and Table S20). All these emissions result mainly from operation independently of the vehicle type. The production of the battery, the glider, and the drivetrain also emits considerable amounts of PM10, NOx, and SO2.

—Notter et al.

A breakeven analysis showed that an ICEV would need to consume less than 3.9 L/100km (60 mpg US) to cause lower CED than a BEV or less than 2.6 L/100km (90 mpg US) to cause a lower EI99 H/A score. Consumptions in this range are achieved by some small and very efficient diesel ICEVs, the authors noted.

Resources

  • Dominic A. Notter, Marcel Gauch, Rolf Widmer, Patrick Wäger, Anna Stamp, Rainer Zah and Hans-Jörg Althaus (2010) Contribution of Li-Ion Batteries to the Environmental Impact of Electric Vehicles. Environ. Sci. Technol., Article ASAP doi: 10.1021/es903729a


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