Environmental performance of electric vehicles, a life cycle system approach

Scriptie/Masterproef: Doctoral Thesis


How to compare the environmental performance of different vehicle technologies? Vehicles with lower tailpipe emissions are perceived as cleaner. However, does it make sense to look only to tailpipe emissions? Limiting the comparison only on these emissions denies the fact that there are emissions involved during the production of a fuel and gives too much advantage to zero-tailpipe vehicles like battery electric vehicles (BEV). Would it be enough to combine fuel production and tailpipe emissions? Especially when comparing the environmental performance of alternative vehicle technologies the emissions during production of the specific components and their appropriate end-of-life treatment processes should also be taken into account. So the complete life cycle of the vehicle should be included in order to avoid problem shifting from one life phase to another. A vehicle's life cycle can be divided into four stages: vehicle production from extraction of raw materials to delivery of the complete product, production of the fuel and/or electricity used by the vehicle during its life, the impact of vehicle use, and finally vehicle disposal at the end of its life. Within this study, a full LCA of Petrol, Diesel, Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), Hybrid Electric, Battery Electric (BEV) an plug-in hybrid vehicles (PHEV) has been performed with a range based LCA approach.
One of the shortcomings in vehicle LCA is the lack of incorporating uncertainties. In most studies environmental impacts are shown with single values. The complexity, uncertainty and variability of the system are not well approximated with traditional LCA, based on single values. Uncertainties are an inherent part of LCA and should not be avoided but embraced and made explicit in the result. A robust, range based LCA result has to include variabilities and uncertainties.
One of the main contributions towards the international State of the Art is the development of an innovative range-based LCA approach, by including statistical parameter variations into the uncertainty analysis (included into Monte Carlo integrations).
This enables to base policy decisions to be made on a comprehensive analysis that shows the variability in the result.

Furthermore, the dissertation focusses on collecting a new 'detailed' life cycle inventory (LCI) of electric vehicle components including; batteries, power electronics, electric motors and the charging infrastructure. Dedicated LCA models are developed to treat battery electric vehicles, plug-in hybrids (with different ranges and batteries) and hybrid electric vehicles (HEV).
The main driver of the environmental performance of a battery electric vehicle is the electricity production. In most LCA studies, dealing with the environmental impact of BEV, the electricity consumption is derived from general databases. The problem that arises is that often the data is outdated in these general databases. This has an effect on the assumed electricity mix. Which contained for instance more coal based electricity in the past. As stricter regulations are forcing electricity producers to have efficient power plants with after treatment that clean the waste gases, the difference between outdated and current emissions of power plants is large.
Different vehicle technologies have been compared. A BEV offers for many environmental impacts on midpoint level a significant reduction compared with conventional vehicles. This holds also for endpoint damage categories, the BEV have the lowest damages on the three areas of protection. The damage categories are human health, ecosystem diversity and resource depletion.
The environmental impact of a BEV is mostly related to the manufacturing stage of the vehicle and the production of electricity.
The energy source used to produce electricity is highly influencing the environmental performance of a BEV. A BEV powered with hydro, wind or nuclear energy has an environmental impact (calculated as a single score with Recipe) that is 5 times smaller than a BEV powered with hard coal or oil. Renewable electricity coupled with electric vehicles is a large opportunity for the future. Powering electric vehicles with hard coal or oil makes that the BEV has the same impact compared with a petrol and a diesel vehicles.
In the future it is expected that impacts related to manufacturing of components of electric vehicles can be improved.
Together with a growing share of renewable electricity the impact of a BEV can be further lowered. Nevertheless, implying good environmental solutions might prove to be not always that straightforward as for instance from copper mining is outside European borders.
However, these impacts can be looked at as opportunities to make BEV more environmental friendly in the future. The life cycle approach enables a clear understanding of the environmental issues involved in the full life of a vehicle. Furthermore, it shows the processes that contribute most; this makes LCA an interesting ecodesign tool. If LCA is used during the development of a new electric vehicle, the environmental opportunities of a BEV can be thoroughly exploited.
Datum prijs1 jul 2013
Originele taalEnglish
Prijsuitreikende instantie
  • Vrije Universiteit Brussel
BegeleiderJoeri Van Mierlo (Promotor) & Cathy Macharis (Co-promotor)

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