Achieving the right balance?
Once a car engine and pollution-reduction system have been
designed, built, and mounted in a vehicle, adjustments can be made to
tailor the emission levels, fuel economy, and engine power. A modern
vehicle contains sophisticated control systems that can fine-tune the
engine, as needed, to provide drivers with the performance they require
in a given moment. For instance, the car may give you a boost of power
in moments of high acceleration or when scaling a steep incline. As a
result of these control systems, computers are playing an increasingly
crucial role in tailoring and maintaining the performance of the modern
In November 2015, Volkswagen admitted to tampering with the
software on several models of their diesel cars to slip past government
regulators, with significantly higher exhaust emissions than allowed by
law. Tests have shown that Volkswagen installed “defeat devices” on its
3.0-L diesel-model cars since 2009.
The evidence collected so far shows that Volkswagen engineers had
installed an additional piece of software that turned off the function of
the NOx adsorption sieve during normal driving conditions—effectively
putting it in a state of high fuel economy, but also high emissions. The
same software then reversed the settings (by restarting the NOx sieve)
to put it into a
low-emissions and low-fuel-economy mode when it
was tested by regulators.
Until now, such
emissions tests were
typically performed on a
stationary test bed, and
the offending software
regulators into underestimating the vehicle
emissions under the test
conditions. In contrast,
under real-world driving
conditions, the emissions exceeded regulations by as much as 40 times. These extra pollutants cause urban smog and can lead to respiratory problems.
Where do we go from here?
In the short term, government regulators are on high alert, and many
of the Volkswagen cars are being recalled and repaired to bring their
emissions back to within specifications. These adjustments will likely
come with a reduction in power and fuel economy.
For the car of the future, we can expect additional developments in
the engine’s combustion chamber, where advances are already leading to more efficient fuel use. Car manufacturers are also
researching new lightweight materials, such as
aluminum and carbon fiber, which would provide a
boost to fuel economy without having to compromise on air pollution and engine power.
Also, advances in catalytic converters and methods for reducing
nitrogen oxide emissions are limiting the pollution that exits the tailpipe
to a greater degree with every technological generation. In particular,
combinations of multiple pollution-reducing devices within one system
are likely to become the norm.
In the coming years, we can expect other fuels to have a chance to
gain a foothold in the car market. Cars fueled by natural gas—primarily
made up of methane (CH4)—or hydrogen gas are also topics of current
research. In the case of hydrogen, the emissions would be composed
entirely of water, at least in the ideal case.
Another idea is to eliminate emissions altogether. Fully electric
vehicles and hybrid-electric models currently make up less than 2% of
all vehicles sold, but this may increase if the supporting infrastructure
can keep up and if fuel prices rise. For these technologies, advances in
battery electrical storage could be a game-changer.
Diesel- and gasoline-fueled car engines have served us well, and they
will not be going anywhere anytime soon. The modern car is cleaner
now than at any other time in its history, and car developers are working
on ideas that should make them even better. Many new technologies are
already waiting in the wings, and the future of the car promises to be
even cleaner yet.
Niedermeyer, E. VW’s Diesel Crisis Is Now a Global Threat. Bloomberg View,
April 22, 2016: http://www.bloombergview.com/articles/2016-04-22/vw-s-
diesel-crisis-is-now-a-global-threat [accessed Nov 2016].
Morgan, D. West Virginia Engineer Proves to Be a David to VW’s Goliath.
Reuters, Sept 23, 2015: http://www.reuters.com/article/us-usa-volkswagen-
researchers-idUSKCN0RM2D720150923 [accessed Nov 2016].
John Uhlrich is a science writer located in Mannheim, Germany. This is his first
article in ChemMatters.
Advances in catalytic converters
and methods for reducing nitrogen
oxide emissions are limiting the
pollution that exits the tailpipe to a
greater degree with every technological generation.
Modern engines, such as the ones shown here,
are fine-tuned by control systems inside a car
to improve their power.