Prof. Harry Watson, Part Time Prof, University of Melbourne
Paper Title Extra CO2 Emitted when In-Service Life not Optimized for Minimum CO2 – Comparison of ICEs, BEVs and H2 (FCEV and ICE)
Harry Watson, Emeritus Prof. University of Melbourne, Australia
KEYWORDS Vehicle life, Life cycle analysis, hydrogen fuel, electric vehicles, cars, sustainability
Research /Engineering Questions It was recognised by ‘The Club of Rome’ in 1948 that the earth’s resources were limited and by 1971 in the book ‘Fundamentals of Exhaust Emissions’ I concluded that we should also have concern for CO2 levels in the air and consequent global warming caused by transport emissions. So, what is the optimum strategy for minimizing energy use and emissions, recognizing that the car is the prime source of personal space for mobility, and although many governments support a focus as EVs the embodied CO2 in batteries, H2 fuel tanks etc. are significant contributors to Life Cycle Analysis (LCA) or carbon footprint.. What are the optimum lifetimes compared with traditional in-service lives and the consequences in CO2 emissions.
Objective To demonstrate that in-service whole-of-life mileage has a significant influence on the optimum life cycle CO2 for BEVs and for two classes of H2 fueled cars as well as ICEs. Thus, to determine how much present, typical in-service mileage differs from the optimums against a back drop of steadily improving energy efficiency, as new vehicle designs enter the market along with the greening of manufacturing, electric power supply and battery manufacturing energy,
Methodology Using the best available energy production and usage data, life cycle analysis (more than ‘well-to-wheel’ as the energy content and manufacture of consumables and recycling/reuse is included) is performed for the vehicles, accounting for the change in vehicle use as the vehicle ages, and in which new vehicles replace older, scrapped ones in the market, with improvements in energy efficiency (and reductions CO2 emissions). The present in-service mileage at the time of vehicle scrapping/recycling varies around the world. Europe is taken as the focus, where end of life mileage is around 170,000 km and 18 years, but it is shown how other regions may be easily considered.
Results Depending on the vehicle size and configuration, the optimum vehicle life ranges from 11 years to more than thirty; significantly different from 18 years. For all forms of EVs the greater the installed battery kWh or H2 tank size and hence range capability, the longer is the optimum service life. As the incremental energy efficiency trend for new vehicles entering the market reduces, as it must according to the law of diminishing returns, vehicles need to stay in use for longer to amortize the embodied energy in manufacturing even though this continues to improve.
Limitations The analysis is only as reliable as the data. However the sensitivity analysis allows the results to remain useful as the user can adjust the scenario according to updated information. No economic analysis is performed but such analysis is more complex because costs are more variable than the regional variety in global vehicle design.
Novelty The sensitivity analysis allows the reader to apply the results for regional variables such as the proportion of renewable energy in electricity generation and, included is the consequence of EVs reduced annual travel compared with conventional and hybrid light duty vehicles.. The application of the most recent input data is also novel. Finally, the author is not aware of analyses of this type that includes reducing annual travel as vehicles’ age, rather constant km of travel per year has previously been assumed throughout the vehicle life.
Conclusion This paper extends the concepts developed in FISITA’s upcoming white paper. On the basis of the median results from the projections, short to moderate range EVs offer the best path to minimizing CO2 emissions which conflicts with the general consumer desire for increased range to reduce ‘range anxiety’ and frequency of recharging. The benefits of up to 20% reduced life cycle emissions by optimal age recycling of the vehicle. Under these conditions of optimum age usage it can be seen that the switch to EVs is not so urgent (in line with the white paper message) if policies are in place that encourage best use of all vehicles.