Local authorities that successfully bid for the Department for Transport’s Clean Vehicle Technology Fund may fall into the NOx trap, warns Emissions Analytics - a provider of real-world emissions measurement.
Aimed at tackling the issue of rising NOx levels, the Clean Vehicle Technology Fund provides support and guidance, with a total of £5 million available for councils to help fund improvements to local bus and vehicle fleets.
As part of the scheme, they are required to document how they will monitor and evaluate real-world emissions. This could include the use of a realistic test cycle, as well as portable emission monitoring systems or on-street monitoring.
However, with a sizable difference between theoretical and real-world vehicle emissions, many authorities may struggle to select the vehicles that have the greatest impact on air quality, suggests Emissions Analytics.
The EU regulations for both NOx and miles per gallon are calculated using the New European Drive Cycle test, which provides theoretical emissions figures for each vehicle. However, these tests fail to predict the real-world emissions of vehicles when used on public roads.
Having conducted over 400 vehicle emissions tests to date, Emissions Analytics claims to be the most experienced emissions measurement specialist in Europe.
It believes that on average the deficiency between official and real world emissions figures is 22%. This disparity becomes an issue as air quality assessment is monitored by roadside gas analysers, which record ambient pollution.
As a result, local authorities may inadvertently allocate funds to vehicles that fail to deliver on their promise of cleaner air.
Emissions Analytics is developing a new traffic simulation model which will calculate the effect of speed and congestion on fuel economy, as well greenhouse gas (CO2) and air pollution (NOx and CO) components.
Underpinned by the data from its real-world tests, this advanced simulation aims to help local authorities select the best vehicles.
“Choosing a vehicle on the basis of its theoretical emissions, without understanding how it operates in the real world, is a lottery,” explained Nick Molden, founder and CEO of Emissions Analytics.
“It’s quite possible to select a vehicle that theoretically will help reduce NOx emissions, only to find that it has a negative impact on real-world emissions.”
Although vehicle manufacturers have introduced a number of modifications to meet the ever tightening controls of NOx emissions, a study conducted by Imperial College London and Emissions Analytics, on Euro 5 light-duty diesels, shows that in most cases real-world figures exceed Euro 5 standards threefold.
The study found a direct correlation between lower vehicle speed and higher NOx emissions, and also found that short periods of acceleration also made a significant impact.
With many towns and cities in the UK experiencing high levels of congestion, the real world emissions of ‘greener’ vehicles could be substantially higher than fleet operators anticipate.