Reports of my death are grossly exaggerated
Diesel isn't dead, and anyone who thinks otherwise, (politicians), needs to spend more time talking to industry experts
We've all seen the headlines about the demise of diesel. Volkswagen's diesel-gate didn't help the fuel's appearance but in a world where we're trying to minimise emissions of all kinds we can't afford to simply ignore oil-burning technology.
Diesel is far better at minimising CO2 emissions than petrol, and although NOx and PM emissions maybe higher, they can also be driven down if we're sensible about it and don't panic. Unfortunately not panicking isn't something that politicians are very good at.
Since 2017, European legislation has required new passenger cars tested according to an RDE-compliant mix of urban, extra-urban, and freeway cycles emit no more than 168 milligrams of NOx per kilometre.
As of 2020, this limit will be cut to 120 milligrams. But even today, one of the largest suppliers in the automotive industry, Bosch, says vehicles equipped with its diesel technology can achieve as little as 13 milligrams of NOx in standard legally-compliant RDE cycles. That's quite a statement and one everyone should take note of.
That is approximately one-tenth of the prescribed limit that will apply after 2020. And even when driving in particularly challenging urban conditions, where test parameters are well in excess of legal requirements, the average emissions of the Bosch test vehicles are as low as 40 milligrams per kilometre.
Bosch's engineers have achieved this over the past few months from a combination of advanced fuel-injection technology, a newly developed air management system, and intelligent temperature management.
NOx emissions can now remain below the legally permitted level in all driving situations, irrespective of whether the vehicle is driven dynamically or slowly, in freezing conditions or in summer temperatures, on the freeway or in congested city traffic.
“Diesel will remain an option in urban traffic, whether drivers are trades people or commuters,” said Bosch CEO Dr Volkmar Denner.
As the measures to reduce NOx emissions do not significantly impact consumption, the diesel retains its comparative advantage in terms of fuel economy, CO2 emissions, and therefore climate-friendliness. And that's what everyone wants from a fuel.
And, according to Bosch, even with this technological advance, the diesel engine has not yet reached its full development potential. The firm now aims to use artificial intelligence to build on these latest advances. This will mark another step toward a major landmark: the development of a combustion engine that – with the exception of CO2 – has virtually no impact on the ambient air.
“We firmly believe that the diesel engine will continue to play an important role in the options for future mobility. Until electromobility breaks through to the mass market, we will still need these highly efficient combustion engines,” Denner said.
His ambitious target for Bosch engineers is the development of a new generation of diesel and gasoline engines that produce no significant particulate or NOx emissions. Even at Stuttgart’s Neckartor, a notorious pollution black spot, he wants future combustion engines to be responsible for no more than one microgram of NOx per cubic meter of ambient air – the equivalent of one-fortieth, or 2.5%, of today’s limit of 40 micrograms per cubic meter.
So let's not start announcing the death of diesel just yet, as we move forward we'll need all of the fuel types and technologies at our disposal to meet emissions targets while at the same time maintaining current levels of individual mobility.
Q&A: Bosch 's answer to reducing diesel emissions
What distinguishes the new diesel technology?
To date, two factors have hindered the reduction of NOx emissions in diesel vehicles. The first of these is driving style. The technological solution developed by Bosch is a highly responsive air-flow management system for the engine. A dynamic driving style demands an equally dynamic recirculation of exhaust gases. This can be achieved with the use of a RDE-optimised turbocharger that reacts more quickly than conventional turbochargers. Thanks to a combination of high- and low-pressure exhaust-gas recirculation, the air-flow management system becomes even more flexible. This means drivers can drive off at speed without a spike in emissions. Equally important is the influence of temperature. To ensure optimum NOx conversion, the exhaust gases must be hotter than 200 C. In urban driving, vehicles frequently fail to reach this temperature. Bosch has therefore opted for a sophisticated thermal management system for the diesel engine. This actively regulates the exhaust-gas temperature, thereby ensuring that the exhaust system stays hot enough to function within a stable temperature range and that emissions remain at a low level.
When will the technology be ready for production?
Bosch’s new diesel system is based on components that are already available in the market. It is available to customers effective immediately and can be incorporated into production projects.
Why is urban driving more demanding than extra-urban or freeway driving?
To ensure optimum NOx conversion, the exhaust gases must be hotter than 200 C. This temperature is often not reached in urban driving, when cars are stuck in gridlock or stop-and-go traffic. As a result, the exhaust system cools down. Bosch’s new thermal management system remedies this problem by actively regulating the exhaust gas temperature.
Does the temperature regulation require an auxiliary 48V heater installed in the exhaust-gas system or additional components of a similar kind?
Bosch’s new diesel system is based on components already available in the market and does not require an additional 48V on-board electrical system.
Will the new Bosch technology make the diesel engine significantly more expensive?
The Bosch diesel technology is based on components already in use in production vehicles. The decisive advance comes from a new combination of existing technology. It does not require any additional hardware components. So reducing emissions will not make diesel vehicles any less affordable.
Will the diesel engine lose its comparative advantage in fuel economy and climate-friendliness as a result of the new technology?
No. Our engineers’ goal was clear: to reduce NOx emissions while retaining the diesel’s comparative advantage in terms of CO2 emissions. Diesel will thus remain a climate-friendly option.