Efficiency and CO2 emission analysis of Internal Combustion Engines (ICE) and Electric Vehicles (EV)

This blog is an addition to a study commissioned by the Austrian Ministry for Transport, Innovation and Technology and the Federation of the Austrian economy [1]. We want to stress the significance of transparent information regarding the vehicles efficiency and the environmental footprint.

In Austria, an Electric Vehicle (EV) needs to drive 80.000km to have lower CO2 emissions as an Internal Combustion Engine (ICE) due to the electricity mix of the country. In countries with an electricity production depending heavily on coal like Poland and China, the EVs will always have higher CO2 emissions than an ICE. To provide you a better overview a summary of the essential drivetrain efficiency and CO2 emissions is provided.

Analysing various fuel productions and drivetrains:

For an objective analysis of the overall efficiency of a drivetrain, the entire energy chain must be examined. At the moment this is called well-to-wheel analysis, which investigates the used energy and the efficiency from the energy source to the wheel. The overall efficiency is strongly influenced by energy production. The well-to-tank analysis provides information on the efficiency of energy generation (how much energy is lost during e. g. electric power generation). The tank-to-wheel analyses refer to the used energy in vehicles from the tank system to the road.

Figure 1.1 explains the well-to-wheel analysis with the subcategories well-to-tank and tank-to-wheel.

Figure 1.1: Conceptual illustration of Well-to-Wheel analyses for efficiency and CO2 emissions (Source: Own illustration based on [2])

Well-to-tank analysis:

Figure 1.2 gives an overview of the efficiency in energy production of fuels. Minimum or fixed values are displayed in violet. Values that are dependent on the efficiency of the used production method are striped violet. Values for the EU electricity mix are marked in blue and the values for the Austrian electricity mix are marked in red.

With little effort raw natural gas is produced by drying and desulphurisation at efficiencies around 90%. The production and supply of fossil fuels, such as petrol and diesel, from is also produced at high efficiencies of up to 85%. Production efficiency of bio-fuels gaseous is strongly dependent on the raw material and the processing method, typical efficiencies between 15 and 50%. Hydrogen can be produced at efficiencies of between 10 and 80%, both in the production from methane and in the production with electrolysis, values of up to 80% can be achieved. The generation of electricity takes place between 15 and 90% efficiency.

Figure 1.2: Well-to-Tank analysis of the efficiency (Source: Own illustration based on [3])

Figure 1.3 shows the CO2 emissions of the well-to-tank analysis. The production of fossil fuels cause emissions of approximately 50 g CO2/kWh for petrol and diesel. Biogenic fuels are often described as CO2-neutral, because of the collected CO2 due to photosynthesis during the growth process of the plants. However, depending on the raw material used and the manufacturing process, a broad spectrum of greenhouse gas emissions is produced. Some production methods produce higher CO2 emissions than fossil fuels and produce fewer greenhouse gases than the plant collects through photosynthesis. For electricity, the values lie between 15 g CO2/kWh when generated from wind energy and over 1000 g CO2/kWh from lignite production. With the EU electricity mix 340 g CO2/kWh are produced. If hydrogen is produced by electrolysis, the emission loads can vary from 21 g CO2/kWh to 1400 g CO2/kWh. The value for the European electricity mix is approximately 425 g CO2/kWh and for the Austrian electricity mix 129 g CO2/kWh.

Figure 1.3: Well-to-Tank analysis of CO2 emissions (Source: Own illustration based on [3])

Tank-to-Wheel efficiencies and CO2 emissions

Despite these developments, the combustion engine is not very efficient compared to alternative propulsion technologies. Tank-to-wheel analyses refer to the used energy in vehicles from the tank system to the road. The petrol engine can achieve an efficiency of up to 35% at the best point, and an average of 20% in a driving mode according to the NEDC driving cycle. The diesel engine reaches approx. 45% at its best point and approx. 28% in a driving mode according to the NEDC driving cycle.

The battery-powered electric vehicle can achieve an efficiency of more than 85% at the best point, in driving mode (NEDC driving cycle) an average of 60 – 75% is achieved. The fuel cell vehicle can achieve an efficiency of more than 65% at its best point, in transient driving mode (NEDC driving cycle) an average of 40-55% is achieved.

Figure 1.4: Tank-to-Wheel analysis of CO2 emissions of different vehicle segments and drivetrains (Source: Own illustration based on [3])

The emissions in g CO2 per km tested on the NEFZ cycle for different vehicle segments (B/small cars, C/medium cars, F/luxury cars) and drive trains is shown in Figure 1.4. Vehicles with battery-powered electric motors or hydrogen-powered FCEV as well as hydrogen-powered combustion engines are CO2-free in operation.

Well-to-Wheel efficiencies and CO2 emissions

For an objective analysis of the overall efficiency of a drivetrain concept, the entire energy chain must be examined. This is called well-to-wheel analysis, which investigates the used energy and the efficiency from the energy source to the wheel. The overall efficiency is strongly influenced by energy production. For petrol engines, the Well-to-Wheel efficiency drops and reaches between 14% and 20%. The diesel engine still achieves 21% to 26% overall efficiency.

With BEVs, the well-to-wheel efficiency drops to approx. 32% with the EU electricity mix. With the Austrian electricity mix, an overall efficiency of approx. 50% is possible. With FCEV, the well-to-wheel efficiency drops to approx. 22% due to the high energy consumption with the EU electricity mix. With the Austrian electricity mix, an overall efficiency of approx. 34% is possible. This corresponds to a higher degree of efficiency than with combustion engines.

Figure 1.5: Well-to-Wheel analysis of CO2 emissions of different vehicle segments and drivetrains (Source: Own illustration based on [3])

For the determination of the total CO2 emissions, the values of the tank-to-wheel and well-to-wheel are summed up for the well-to-wheel analysis, shown in Figure 1.5. The range of the BEV reaches from a CO2 free operation with energy from renewable energy sources to electricity produced with lignite. For FCEV and internal combustion engines the range is between electrolysis from renewable electricity to lignite produced electricity. The Austrian Energy mix is shown with red bars and the EU energy mix is marked with the blue bars.

With the Well-to-Wheel analysis it is possible to assess the efficiency of drivetrains and the energy transport/production. The analysis above was made with the NEDC test cycle. It is to be expected that with the new WLTP test cycle the CO2 emissions will increase about 20%. Another disadvantage is that, the analysis gives no information about the raw material production (steel, aluminium, …), the production of the vehicle itself, the recycling and the disposal of the vehicle. An analysis considering the use phase, the energy supply and the product life cycle is called Cradle-to-Grave analysis. Only with the Cradle-to-Grave analysis the vehicles can be compared objectively and as a whole. The other methods will lead to insecure customers and false information.

What can be seen very clearly with the Well-to-Wheel analysis is that the electrification of the drivetrain requires an energy revolution towards sustainable energy production.

Authors: Dr. Hans-Peter Kleebinder, Michael Semmer


[1] H.-P. Dr. Kleebinder, A. Dr. Kleissner, and M. Semmer, “Auf der Siegerstraße bleiben! Automotive Cluster der Zukunft bauen.,” Wien, Nov. 2019.

[2] Mazda, MAZDA: Aiming to Make Cars that are Sustainable with the Earth and Society. [Online] Available: https://www.mazda.com/en/csr/special/2016_01/. Accessed on: Nov. 06 2019.

[3] M. Klell, H. Eichlseder, and A. Trattner, Wasserstoff in der Fahrzeugtechnik: Erzeugung, Speicherung, Anwendung, 4th ed. Wiesbaden: Springer Vieweg, 2018.

Thumbnail by Petovarga – stock.adobe.com

On May 16, 2018, the University of Applied Sciences Fresenius Munich presented and discussed the topic “Designing Digital Cities” for the first time together with the Academy for Fashion and Design AMD at the Zukunfts Forum (Future Forum) 2018:

  1. How do we live and move in the future?
  2. Which technologies will become important and what does this mean for people?
  3. How does #NewMobility affect our quality of life?

Munich can look to the future, but other cities are currently faster

In the fully occupied Audimax, curator and presenter Dr. Hans-Peter Kleebinder greeted the audience and three global experts from the metropolises of London, Shanghai and Copenhagen with a strong personal connection to Munich with the following question:

What must happen that Munich, as the epicenter of the mobility industry, once again experiences a similar modernization push as it did last in 1972 at the Olympics?  

What are the premises and possible solutions for this?  

Munich has already shown convincingly how to cope with the future: In the only six years from 1966 to 1972, the city made itself fit for its 1972 Olympic Games and catapulted itself forward by a whole generation span with the infrastructure created for this purpose.

Car traffic shapes our cities

Our cities today are infrastructure built around the automobile. The basis for this is the 1920 Athens Charter, which postulated the separation of living, producing and shopping as the basis for global urbanization. This flood of cars has taken over the cities through urban highways and expressways. Almost all other available areas were diverted for parking traffic. In major German cities, traffic and parking space account for around 40 percent of the total urban area, in Los Angeles 80 percent. Nevertheless, people in cars are by no means always mobile. In Beijing, the Chinese capital, people spend 75 minutes a day, well over an hour in traffic jams; that’s about one working day a week. In Los Angeles, motorists spend more than 100 hours a year in traffic jams, in New York over 90, in Munich over 50, in Hamburg, Berlin and Stuttgart 44, in Cologne and the Ruhr 40 – in other words, more than one working week a year even there.

Urbanization as a driver of traffic congestion and air pollution

Contemporary and sustainable quality of life looks different. Once upon a time, the separation of functions in cities should serve, among other things, to improve air quality in residential areas. Today, road traffic pollutes the air everywhere in cities massively. Just one example: In Paris, air quality is the top priority issue for the population;47 percent of respondents cite it first, followed by housing (46 percent) and education (37 percent). Anyone who wants to improve our quality of life must move from outdated auto-centered mobility to “human-centered” #NEWMobility, a new form of mobility that does not reduce voluntary mobility and requires multimodal transport services, i.e. choices between sufficiently short footpaths, sufficiently safe cycle paths, sufficiently frequent buses and trains, and easy transfer options.

  • Collective taxi (in Dubai, electronically linked pods of the start-up NEXT are on the move),
  • car sharing (1.7 million people in Germany used it in 2017) and
  • ride sharing (BlaBlaCar as the EU market leader with 55 million rides in 2017).

A basic requirement of this multi- and intermodal #NEWMobility is its availability, another is its networking. In London, this is done by the Citymapper app and creates transparency about the available means of transport for the mobility route preferred by the individual situation and person. One solution is an app on your smartphone or Smartwatch as a personal assistant for the organisation of individual mobility needs – the travel agency for every route from A to B in your jacket pocket, which individualizes and anticipates and learns to reserve, book and bill for us.  

These possible premises and concrete solutions of one of the climate-neutral, intermodal and networked #NEWMobility outlined the “Future Forum 2018: Designing Digital Cities” of the Fresenius University of Applied Sciences on 16 May 2018 in Munich.

Solutions from Copenhagen, Shanghai and London

Jon Pers, Head of Innovation at the Danish Innovation Center in Munich, presented the example of Copenhagen: The city has to decide what it spends money on: whether for pedestrians, cyclists or the car. In the Danish capital, local politics has given priority to sustainability, liveability and technology, with cycling being given priority 1. The result: 45 percent of commuters come to work or school by bicycle.

Dr. Rainer Daude, responsible for new mobility concepts at the BMW Group, presented “Vision E³ Way”, an innovative solution approach for megacities. E³ stands for “elevated, electric, efficient” – the characteristic features of the idea, which was developed in and for Shanghai: a modular, largely roofed and thus comfortable and safe elevated road over the existing city highways as a model for electrified pedelecs, scooters and motorcycles. The speed of these vehicles will be limited to 25 km/h and electronically controlled – with free driving on intersection-free routes. Will there be robot routes in the future according to this model, lanes for self-propelled cars, alongside car, pedestrian, bicycle and bus lanes?  Munich, as the Future Forum showed, with its mobility-oriented hardware and software companies is predestined for #NEWMobility as a model city and global #NEWMobility hub:

  • Traditional mobility companies such as BMW and MAN and within a radius of only 245 kilometres Mercedes, Porsche and Audi, new mobility offers such as FLIXBUS/Flixmobility, Clunno but also new mobility providers Lilium Aviation, Volocopter, the TU project Hyperloop and
  • new players on the market such as Tesla, Sono Motors, Byton and Faraday and the EU Mobility Cluster of TUM.

So far, however, other cities and metropolises such as Singapore, Dubai, Paris and London have outstripped the Bavarian metropolis.

The author and consultant for #NEWMobility, Lukas Neckermann, who grew up in the USA and works in London and Munich, was not surprised. The more traditional mobility providers, especially automobile manufacturers, are rooted in a location, the more the question of how their jobs can also be preserved in #NEWMobility counts. Neckermann calculated ahead: Private cars, which are usually only used in the morning and evening on the way to and from work, stand around 95 percent of the day unused. In Car-Sharing, cars are used intelligently six times more often than a private car several times a day. If everyone were to use Car-Sharing services and if flexible working hours allowed this, the demand for new private cars could be reduced to one-sixth – a blessing for cities plagued by cars, but an existential problem for car manufacturers. Even if they can cope with climate change with electric cars as a necessary (transitional) solution. Digitization and #NEWMobility will transform the image of our cities

As the discussion moderated by Dr. Hans-Peter Kleebinder at the Future Forum showed, #NEWMobility has not only friends, but also natural opponents. Nevertheless, it must and will come and give answers to the questions:

  • Will our city still look like a city in the future? 
  • Will our car still look like a car in the future?

The digital revolution offers new approaches, solutions and design possibilities for improving our quality of life for a better and more sustainable future for us and our future generations.