Spanner in clean diesel?

The Volkswagen cheating episode underlines the desperation of the diesel vehicle industry to survive the stricter emissions standards being introduced by governments across the world. While Volkswagen attempted to circumvent stringent emissions standards, evidence from Europe and the US show that several other clean diesel brands are struggling to maintain low NOx emissions during real-world driving. In 2013, the International Council o Clean Transport (ICCT) conducted a study in Europe and found that on-road NOx emissions exceed at least seven times the certified limit under the Euro VI standards—the best emission standard in Europe today.

Equally shocking is the revelation by European non-profit, Transport and Environment, which in 2015 found that nine of the ten new diesel cars sold in the continent did not meet emission limits under the Euro VI standard.

The researchers say advanced electronics and sophisticated emissions control systems in the diesel segment are the prime reason for this anomaly. These systems help achieve clean emissions, but making them perform throughout the vehicle’s lifetime without much deterioration on the road is a challenge.

It is therefore not surprising that Europe, which has dieselised significantly in the hope of curbing greenhouse gas emissions, is struggling to resolve the high NOx problem. When compared with petrol cars, diesel cars are more fuel efficient and emit less carbon dioxide, a greenhouse gas. But it has remained a complex engineering challenge globally to make diesel vehicles fuel-efficient as well as low emitters of both particulate matter and NOx emissions—technical solution to lower one raises the other.

This is one of the reasons Europe has kept diesel norms comparatively lax for a long time. In fact, its current Euro VI standards are 50 per cent less strict than the current standards in the US. Its standards also allow diesel vehicles to emit more NOx than petrol vehicles. On the other hand, the US, which has same norms for diesel and petrol vehicles, also requires vehicles to have emission control systems with 20 per cent higher durability than that in Europe.

Today, several European cities are facing the brunt of errant diesel emissions. Even after introducing tighter emissions standards of Euro V and Euro VI, several European cities are failing to meet the targets of ambient air quality standards for NOx. Last year, the UK was dragged to the European Court of Justice for violating the ambient NOx standards. This has led to a serious backlash against diesel cars that are one of the primary sources of NOx. Eight cities in the UK are planning to ban diesel cars, and more cities in Europe have banned them in areas declared low emission zones. Paris is restricting diesel car use.

The Volkswagen case is now set to change the regulatory regime in the US and Europe—the worst affected by the fraud. The US is the first country to have drafted rules to prohibit defeat devices in vehicles way back in 1978. It also has the most elaborate system to make manufacturers accountable for their emissions performance on the road. It could not detect the cheating by Volkswagen. But it at least had the system in place to act quickly when the problem was brought to them. Michael Walsh, who played a crucial role in drafting the original defeat device rule in US Environmental Protection Agency (USEPA) while heading its motor vehicle division, says, “We were preemptively staking out our position as computers took over control of vehicle systems. It didn’t take much imagination to think up scenarios that could expand the opportunities for cheating. We were constantly pushing back to establish that industry had a much broader responsibility and could not deliberately defeat the controls.” Small wonder that soon after the Volkswagen incident, USEPA and California Air Resources Board (CARB) on September 25 announced plans to modify their compliance programme to detect defeat devices in vehicles. Emission standards of European countries are not as stringent or explicit as that of the US. But they are now modifying emissions testing procedures to reflect realistic driving conditions.

But these measures may fail to yield the desired result as European regulators do not have the authority to penalise the errant industry yet. So they need to make the whole chain of car manufacturers and the technology vendors who design the engines accountable. So far, Sweden is the only European country that has a system in place that makes manufacturers accountable for the on-road performance of vehicles.

In new cars, software controls everything, right from the engine, gearbox and power windows to controlling and monitoring emission control devices. Volkswagen (VW) clandestinely tweaked this software to reduce the effectiveness of its emission control systems, mainly to achieve fuel efficiency and to avoid being noticed by regulators. Here is how and why Volkswagen fooled the world’s stringent emission regulators for four years.

Modern diesel cars use a complex mix of sensors, electronics, filtration method and catalysts to meet emission standards. To limit NOx, Volkswagen uses two approaches: one, by trapping and reducing NOx emissions from the engine, and the other by treating NOx in the exhaust with urea. Sophisticated software in the Electronic Control Module (ECM) governs this entire process

ECM is the brain of modern cars. Apart from controlling emissions, it senses, monitors and regulates air-fuel mixture, engine temperature, and ignition, exhaust gas temperature and fuel economy. Volkswagen tweaked ECM’s software (US regulators refer to this tweaked software as defeat device) so that the car can sense when it is being tested and make NOx control system work effectively. But once on road, it switches to a different operational mode to reduce effectiveness of NOx control system

Modern emission control devices like NOx control system need the energy to operate and hence require more fuel. Making improvements in both emissions control and fuel economy is, therefore, a challenge to the car maker. It can be tempting to keep some of these systems working at a suboptimal level to achieve higher fuel efficiency. Volkswagen gave into this temptation.