Diesel vehicle emissions could be twice as much as what companies claim, says study

NEW DELHI: A recent study by the International Council on Clean Transportation (ICCT) on oxides of nitrogen (NOx) emissions from diesel vehicles in 11 countries including India has highlighted that “excess NOx emissions” from passenger as well as commercial vehicles can cause a major public health challenge in the future.
This is because scientists have found that on-road emissions of diesel cars are far higher than in lab certification conditions, and therefore they do not meet the standard in real world driving conditions even if they technically comply with the standards in labs.Their compliance with standards for particulate matter (PM) is however much better.
In fact, in India even if BS VI is implemented but without a strong “real-driving emissions program” to ensure low NOx emissions in actual driving conditions, NOx emissions from diesel vehicles will increase manifold. TOI spoke to ICCT researchers who are authors of the study on the impacts India will face.
“Without a strong real-driving emissions program (on-road testing of vehicles), improved compliance and enforcement, diesel cars could continue to emit 4 to 6 times the BS VI NOx limit. The on-road NOx emissions in India in 2015 may be already twice the norms for heavy duty vehicles and more than three times the norms for light duty vehicles our study has shown,” said Anup Bandivadekar, Passenger Vehicles Program Director at ICCT. Real-driving emission (RDE) tests can be carried out with the help of Portable Emission Measurement System (PEMS). These tests that are being implemented in Europe can measure the emissions when the vehicle is being driven.
The study called “Impacts and mitigation of excess diesel related NOx emissions in 11 major vehicle markets” published in Nature journal recently is based on emission inventories for 11 major vehicle markets by combining NOx emission factors, current vehicle regulations in these countries, historical data on diesel vehicle activity, sales and population and projections till 2040. The team has applied a global transportation emission inventory model that has been earlier applied in a number of global and regional studies.
The background to this are a number of instances where diesel vehicles’ real world emissions have been found to be higher than lab certification conditions. In fact Euro VI and US EPA 2010 for both heavy and light duty vehicles in US and Europe have dramatically reduced particulate matter (PM) emissions and other pollutants. “Yet reducing NOx emissions had proved more challenging for diesel vehicles—there is a growing gap between real world NOx emissions and certification limits under tightened emission limits of Euro IV and V,” the study says. The excess NOx emissions from diesel vehicles came to light after 11 million Volkswagen cars in US, Europe and other places were found to be installed with a defeat device – a software that senses when the car is undergoing emission testing and activates emission control systems.
Assuming BSVI is implemented as effectively as Euro VI for heavy-duty vehicles, these standards will reduce NOx emissions from new vehicles by 90% compared to BS IV, adds Bandivadekar. This is due to use of improved testing cycles, as well as a stronger emphasis on durability, and off-cycle emissions testing requirements. The resulting emissions from the in-use heavy vehicle or commercial vehicle fleet will decline by 75% in 2040. But there can be a four-fold increase in NOx emissions by 2040 in India from diesel passenger vehicles even if BS VI is implemented but real driving emissions (RDE) tests are not implemented.
“We have noticed that with Euro VI, the heavy duty vehicles more or less meet the lab certification conditions. But we are seeing continuing problems from diesel cars. We have additional data for India which is yet to be published that corroborates that real world emissions from diesel cars is much higher,” explained Anup Bandivadekar.
The authors also recommend “next generation policies” similar to US Tier 3 emission standards for light-duty vehicles and California Air Resources Board (ARB's) voluntary NOx rule for heavy vehicles. Both of these interventions can achieve a 90% reduction in NOx emissions compared to Euro VI levels according to the study.
What are ICCT’s recommendations to Indian government to counter excess NOx emissions from diesel cars?
1) Adopt a strong real-driving emissions program that includes in-service conformity testing, expanded test conditions, market surveillance/independent testing.
2) Screen for defeat devices, and ensure the legal authority to recall vehicles and issue substantial penalties for manufacturers that cheat (i.e. roughly equal to the purchase price).
3) Consider adopting the petrol limit values for NOx emissions for diesel cars. Even in BS VI standards, diesel cars will be allowed to emit 33% more NOx than petrol cars