How to calculate the environmental impact of electric vehicles? Energirelaterad Fordonsforskning 2017 4&5 Oktober 2017 Patricia van Loon
BACKGROUND 0.16% of all vehicles are fully electric (bilsweden.se, 2017)
Background Estimated impact of electric vehicles (BEVs): EC target by 2021 Messagie et al., 2014 Faria et al., 2013 Frischknecht and Flury, 2011 0 95 190 285 g CO2-eq/km
Existing guideline for LCA electric vehicles: No guidance on relevant and realistic input values
Project FOU Program Energieffektivisering i transportsektorn Review of previous LCA studies (~100 studies) Collection of energy consumption electric vehicles in Sweden Preliminary guidelines Test of guidelines by car manufacturers - NEVS Supplement existing LCA guidelines 2016 2017 2018 Budget: 1 793 200 SEK
Findings from literature review Main findings Urgent need for actual vehicle data, based on modern vehicles More broader system boundaries, e.g. recycling, other environmental impact categories besides GHG emissions, etc. Rigorous and scenario based assessments Standardization on report
Scope
Functional unit and reference flow Environmental impact reported per km driven. Uncertainty in lifespan of vehicles (100.000 to 563.250 km assumed) What are equal cars: Same vehicle class? Same mass? Same mass-to-power ratio? Same drive range? Same volume? How to decide? Tagliaferri et al. (2016) Faria et al. (2013)
Production phase Most studies assume same vehicle, but change propulsion system, which impacts total weight of vehicle. All components can be assumed equal, except (Hawkins et al., 2012): fuel tanks / temperature control systems fuel lines / wires internal combustion engine / electric motor electronic combustion control system / electrical system controls tires / higher mass tires - / additional regenerative braking system Need to be checked with real data from an electric vehicle
Production phase Battery production largely responsible for higher GHG emissions in vehicle production Lithium-ion battery
Production phase Few papers on batteries: Ambrosse and Kendall, 2016 Dunn et al., 2012; 2015 Ellingsen et al., 2013 Kim et al., 2016 Majeau-Bettez et al., 2011 Notter et al., 2010 Oliveira et al., 2015 Wang et al., 2017 Ongoing research: IVL? Wang et al. (2017)
Production phase Infrastructure not often included Nansai et al. (2001) Japan Lucas et al. (2012) Portugal Infrastructure conventional vehicles contributes up to 0.7% of the CO 2 emissions, electric vehicle infrastructure can be responsible for up to 7.9%. Infrastructure should be included
Use phase NEDC will most likely be replaced with WLTC 21% higher energy consumption on road than NEDC Not included in NEDC are: Driving styles (+46% energy consumption possible) Weather conditions (+60% in harsh winter conditions) Path elevation / other terrains Regenerative breaking Auxiliaries (+21% up to +40%)
Use phase Increase in emissions when using real driving instead of NEDC (Renault, 2011): 1.6 l 16v petrol engine Electric motor Abiotic depletion +13% +6% Primary energy demand +12% +9% Global warming potential +12% +6% Acidification +9% +5% Eutrophication +7% +4% Photochemical ozone potential +11% +4%
Use phase Procedure to calculate likely energy consumption of electric vehicle (Del Duce et al. 2016) Step 1: calculate mechanical energy F t t = m v a t + 1 2 C w ρ A v 2 t + C r m v g F t t = force required for traction of vehicle m v = mass of vehicle a t = acceleration v t = speed C w = aerodynamice drag coefficient ρ = air density A = frontal area C r = rolling resistance g = acceleration due to gravity
Use phase Procedure to calculate likely energy consumption of electric vehicle (Del Duce et al., 2016): Step 1: calculate mechanical energy Step 2: multiply with the average efficiency of the entire powertrain, usually 90%.
Use phase Procedure to calculate likely energy consumption of electric vehicle (Del Duce et al., 2016): Step 1: calculate mechanical energy Step 2: multiply with the average efficiency of the entire powertrain Step 3: multiply with 1.15 for real-world driving instead of NEDC Step 4: Add auxiliaries: 0 to 2.8 kwh/100 km Results in 19.9 kwh/100 km However, many LCA studies reduce value to standard NEDC values given by the manufacturer.
Use phase Emissions related to electricity generation: Average annual mix Time dependent average mix Marginal electricity mix No consensus, marginal mix best option? Future changes in electricity network, e.g. more renewables. How to include? Sensitivity analysis advised
Use phase Different charging possibilities: Standard EV loading / uncontrolled charging Least-cost EV charging / off-peak charging Controlled charging by energy provider Vehicle-to-grid charging Environmental impact of charging strategies unclear, some argue that off-peak is more carbon intensive 100% renewable sources should not be used in LCA, unless there is a clear link.
Use phase Should additional renewable energy be used to fuel electric cars or if it would be better to use the renewable capacity to replace coal power plants? (Frischknecht and Flury, 2011)
Use phase Maintenance Non-exhaust emissions (tires, road, brake wear) Innovation (both batteries and ICEVs) Large uncertainty and usually not included in LCA studies
End-of-life Often not included in LCAs g/kg shredded g/kg dismantled g/kg glider BEV powertrain ICE Aluminum scrap 4.2 g 270 g 409 g Copper scrap 6.6 g 125 g 5.7 g Ferrous scrap 654 g 411 g 299 g Plastic 155 g - 135 g Residue 180 g - 153 g Electronic - 194 g component scrap adapted from Del Duce et al., 2016 dismantled
End-of-life (Tagliaferry et al., 2016)
End-of-life Second-use phase of battery (in stationary energy storage system) reduces overall environmental impact of electric vehicle Not part of LCA of electric vehicle? (due to uncertainty and to prevent allocation problems) (Lisbeth Dahllof, IVL)
Impact categories Usually limited More should be included, including but not limited to toxicity, acidification, eutrophication, and water consumption
Conclusions Uncertainty on many factors, including Lifespan of vehicle Comparability of cars Battery production Emissions related to electricity More collaboration between car manufacturers and researchers
Thank you for listening! Any questions? Patricia van Loon Senior Researcher Postdoctoral fellow RISE Viktoria Lindholmspiren 3A 417 56 Göteborg, Sweden Tel: +46 730 48 0160 Mail: patricia.van.loon@ri.se www.viktoria.se INSEAD social innovation centre Boulevard de Constance 77305 Fontainebleau, France Mail: patricia.vanloon@insead.edu www.insead.edu