Automatgenererad bild.

4 June 2015

E4 – Energy efficient reduction of exhausts from vehicles


It has become evident that global warming is currently the most serious threat to the environment. Anthropogenic emissions of CO2 are the largest contributor to the problem. Because a large share of CO2 emissions comes from transportation, measures must be taken in this sector. Emission reductions can be achieved, for example, through the use of renewable biofuels or with the help of fuel cells that produce hydrogen from water with the help of solar energy. An important near-term contribution can be made by developing and stimulating the use of fuel-efficient motors. Although new drive-line concepts (such as hybrids and fuel-cell systems) are emerging, analyses indicate that combustion systems that produce excess oxygen (such as diesel engines) will be the most important engine concept over the next 20 years.

Alongside CO2, it is important to reduce emissions of environmental pollutants such as nitrogen oxides (NOx) and particulates (PM). These emissions can be reduced with the help of different types of exhaust systems, but such systems usually increase fuel consumption.

The goal of this programme is to achieve very low emission levels (0.005g PM/kWh and 0.1g NOx/kWh) with an engine that simultaneously emits low levels of CO2. These emission levels can be compared to the most stringent regulations known to date (0.013g PM/kWh and 0.27g NOx/kWh). These very low emissions levels can be combined with low fuel consumption using advanced exhaust-system components, such as innovative catalyst and substrates, reformer technology and heat recovery. As mentioned above, the disadvantage of current methods of achieving particulate and NOx reductions is the increased fuel consumption that exhaust systems cause.


The goal of the programme is to develop new knowledge and methods for energy-efficient exhaust systems for diesel engines. These methods are independent of fuel type (such as biodiesel, DME, fossil diesel) and – according to well-to-wheel analyses – generate the lowest CO2 levels when using renewable fuels.

Despite the fact that diesel engines are highly efficient, they generate large quantities of waste heat that can be recovered using methods described in the programme plan. This leads to additional CO2 emission reductions.

The programme utilizes achievements in four technological areas: thermo-electrical materials for heat recovery; catalytic NOx reduction with the help of hydrocarbons from the fuel; highly efficient fuel reformation for more efficient NOx reductions at low temperatures, and; innovative metal filters for efficient separation of particulates from exhaust gases.


The results can be used by Swedish industry in a number of sectors, but will also benefit individuals and society at large in the form of improved air quality, i.e. lower levels of local air pollutants and lower emissions of greenhouse gases. The results will even benefit vehicle owners and trucking companies through lower fuel consumption and a cleaner work environment. The results will be useful to decision makers and environmental organizations as supporting documentation for adopting future regulatory requirements.


Programme period:
2006 - 2014

Mistra 20 MSEK

Programme host:
Volvo Technology AB

Programme director:
Heije Westberg

Executive committee chairman
Thomas Johannesson

Contact at Mistra:
Christopher Folkeson Welch

Programme director Heije Westberg.

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