Powertrain Concepts on the Path to CO₂ Neutral Mobility

Authors

Dr.-Ing. M. Brauer, Dr.-Ing. C. Danzer, Dipl.-Ing. M. Kratzsch, Dr.-Ing. M. Leesch, Dipl.-Ing. E. Schneider, Dipl.-Ing. M. Sens, Dipl.-Ing. W. Wukisiewitsch, IAV GmbH, Berlin / Chemnitz

Year

2020

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 813

Summary

The progressive rise in temperature in our atmosphere and the associated climate change will be a major challenge for the environment and the world's population in the long term. Road transport accounts for around 20% of the CO₂ emission in Europe, which is why it is important to set ambitious CO₂ reduction targets for this sector. A first step has already been taken with the CO₂ limits based on the WLTC, but the current legislation, which only refers to tank-to-wheel emissions, has considerable weaknesses and is in this form neither open to technology nor conducive to a transformation towards sustainability and environmental protection.
Battery electric vehicles can and must make an important role to reduce the CO₂ emission. Their use makes sense in areas demanding zero emissions, "stop & go" traffic occurs and low to medium range requirements are set. The reason for this assessment is not only the CO₂ footprint of electricity production, but also the considerable CO₂ equivalent that is already emitted during the production of battery electric vehicles. This applies in particular to vehicles with large batteries and correspondingly high range targets.
This paper presents the results of a parametric study of the real greenhouse gas emissions (or CO₂ equivalent) of different fleet compositions and propulsion technologies for road transport up to the year 2035. The study systematically compares tank-to-wheel, well-to-wheel and life cycle assessment results. Various assumptions and input data are required to conduct the study, which have been presented transparently and compiled with the highest possible degree of objectivity.
The technical optimization potentials of the various powertrain technologies up to the year 2035 will be examined by simulation in preparatory study steps and explained in this article briefly.
The main result of the study is that the different powertrain technologies and fleet compositions do not differ significantly in the real emitted CO₂ equivalent according to life cycle assessment. It would therefore make sense to take the different mobility requirements (zero impact emissions, range, power-to-weight ratio, costs ...) into account when combining the powertrain technologies in the fleet. The study also shows that in order to further reduce the CO₂ emissions according to LCA, the following guidelines must be followed. Otherwise there is no chance of meeting the ambitious CO₂ targets:

• Efficiency improvement measures should be implemented for all powertrain technologies.
• PHEVs should be used rather than BEVs for applications with high range requirements, as it allows a reduction of required battery size.
• The Diesel share in the fleet should be increased rather than reduced.
• The durability and holding time of vehicles should be increased.
• Second-generation biofuels, or fuels generally produced from renewable sources, have the greatest remaining lever on the CO₂ emission according to LCA findings. For this reason, the legally stipulated blending quotas for regenerative fuels should be significantly increased in the near future.