Exhaust Gas Treatment

Exhaust Gas Treatment

Air quality and decarbonisation are linked but are also distinctly different

Across the industry these two issues are often grouped together but they are quite different problems requiring quite different solutions.

Why is Air quality an issue?

Poor air quality, particularly in urban areas, is linked to 29,000 early deaths in the UK each year and an estimated 4.2 million worldwide. Emissions from older internal combustion engines are one of the primary sources of such pollution in urban environments. These emissions include particulates, hydrocarbons, and oxides of nitrogen. Technologies exist to reduce heavy duty diesel engine exhaust emissions and we are experienced in implementing these to deliver cleaner air for our clients.

Whilst some sectors such as automotive have been faster to adopt the implementation of these technologies because of both legislation and consumer pressures, rail rolling stock adoption has been slower for many reasons. Considerations such as the much greater longevity of rail vehicles, demanding duty cycles and packaging constraints on vehicles are all barriers to implementation.

The long life and aging nature of many fleets combined with the lack of public & political focus has slowed adoption of exhaust gas treatment technologies. For example, whilst rail freight delivers better CO2 results than road freight, the same cannot be said for urban air quality emissions. So far incentives and legislation has been largely directed toward the sectors with highest CO2 emissions.

As other industry sectors significantly reduce their exhaust emissions, it is vital that rail is not left behind otherwise it risks both the wrath of the legislator and being shunned by an ever more environmentally conscious consumer. 

Why are Air quality and Decarbonisation different?

One important fact tempers the argument to retrofit modern emissions control equipment to all diesel rollingstock to improve urban air quality:

Adding exhaust gas aftertreatment almost always increases fuel consumption and therefore carbon emissions. 

This is the centre of the thorny issue that puts improved air quality and decarbonisation / carbon intensity potentially in conflict with each other. Striving to improve air quality in stations and depots may result in increasing the carbon emissions overall, if only exhaust aftertreatment is considered. Is this a trade-off worthwhile? Well, we can certainly help to try and answer that question depending on each client's individual requirements. 

Our automotive teams are expert in planning, design, simulation, and implementation of exhaust aftertreatment systems. They can assess whether exhaust aftertreatment is the right option for your air quality and decarbonisation goals. Take a look at our in-house design and test capability here

As our teams also work in many different technology areas, giving a unique technology-agnostic view, we can also advise on whether other alternatives such as selective engine shut down or hybrid "last-mile" drivetrains may offer better opportunities to achieve your air quality and decarbonisation goals within limited budgets.  Contact our team to see how we can help you arrive at the best value solutions to match your ambitions.