Sensitivity Analysis in the Life-Cycle Assessment of Electric vs. Combustion Engine Cars under Approximate Real-World Conditions

Eckard Helmers,Johannes Dietz,Martin Weiss

doi:10.3390/su12031241

Abstract

This study compares the environmental impacts of petrol, diesel, natural gas, and electric vehicles using a process-based attributional life cycle assessment (LCA) and the ReCiPe characterization method that captures 18 impact categories and the single score endpoints. Unlike common practice, we derive the cradle-to-grave inventories from an originally combustion engine VW Caddy that was disassembled and electrified in our laboratory, and its energy consumption was measured on the road. Ecoivent 2.2 and 3.0 emission inventories were contrasted exhibiting basically insignificant impact deviations. Ecoinvent 3.0 emission inventory for the diesel car was additionally updated with recent real-world close emission values and revealed strong increases over four midpoint impact categories, when matched with the standard Ecoinvent 3.0 emission inventory. Producing batteries with photovoltaic electricity instead of Chinese coal-based electricity decreases climate impacts of battery production by 69%. Break-even mileages for the electric VW Caddy to pass the combustion engine models under various conditions in terms of climate change impact ranged from 17,000 to 310,000 km. Break-even mileages, when contrasting the VW Caddy and a mini car (SMART), which was as well electrified, did not show systematic differences. Also, CO2-eq emissions in terms of passenger kilometers travelled (54–158 g CO2-eq/PKT) are fairly similar based on 1 person travelling in the mini car and 1.57 persons in the mid-sized car (VW Caddy). Additionally, under optimized conditions (battery production and use phase utilizing renewable electricity), the two electric cars can compete well in terms of CO2-eq emissions per passenger kilometer with other traffic modes (diesel bus, coach, trains) over lifetime. Only electric buses were found to have lower life cycle carbon emissions (27–52 g CO2-eq/PKT) than the two electric passenger cars.

Highlights

Transport accounts for 23% of the global energy-related CO2 emissions
This is a lesson learned from the European transport emission policy of the past two decades: the primary focus on saving CO2 led to European Union (EU) policy boosting diesel cars to the disadvantage of petrol cars [7,8], which resulted in massive additional NOx emissions and subsequent health costs [9,10]
We modelled with a consumption of 7.02 L/100 km for the analogous 77 kW-diesel model based on 77 vehicles by www.Spritmonitor.de at the time of database access (2015) [55]

Summary

Introduction

Transport accounts for 23% of the global energy-related CO2 emissions. Unlike other sectors, emissions from transport did not decrease but continued to increase annually by 2.5% on average between 2010 and 2015 [1]. Many LCA studies solely focus on climate change [6], further impact categories must be considered to avoid unintended environmental consequences This is a lesson learned from the European transport emission policy of the past two decades: the primary focus on saving CO2 led to EU policy boosting diesel cars to the disadvantage of petrol cars [7,8], which resulted in massive additional NOx emissions and subsequent health costs [9,10]. Corresponding to this, there has been no significant difference until 2015 in the NOx emissions between Euro 5 and Euro 6 diesel cars [14]

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Conclusion