Clearing the air

SCRT equipment can reduce nitorgen dioxide from diesel emissions

Published:  31 August, 2015

Back in May, the Supreme Court ordered the UK government to produce new air quality plans by the end of 2015, for zones exceeding NO2 limits on air quality.

When they made this ruling, which was the culmination of a five year battle fought by ClientEarth, they were unanimous in their decision, saying: ‘The new Government, whatever its political complexion, should be left in no doubt as to the need for immediate action to address this issue.'

ClientEarth's case against the UK Government was centred on a failure to comply with the EU Ambient Air Quality Directive. Central to the case were 16 cities and regions where government plans showed that they would suffer from illegal levels of air pollution long after the limits came into force in 2010.

Some of the UK's largest built up areas including London, Manchester, Leeds, Birmingham and Glasgow are affected. This ruling was against a background of the UK being in breach of European legal limits for NOX and potentially facing a fine by the EU for its failure to meet the regulations. It is predicted by some that local authorities may be liable to pay all or part of any such fines from the EU.

While it may be possible to exclude certain types of vehicles from pollution hotspots, this is not a viable option with essential vehicles such as buses. As a result, cost-effective solutions are needed to reduce emissions, particularly NO2, from existing vehicle fleets.

Aside from the focus on NO2, there is growing evidence of the damaging effects of other exhaust pollutants, such as particulate matter (PM). It has been widely reported that particulate matter (PM) in the air causes around 29,000 deaths in the UK each year.

Of pressing concern are the ultra fine particles within PM that have been shown to cause damage to the heart and lung when inhaled. However, the true figure for premature deaths could be much higher because the 29,000 refers only to those resulting from PM. It excludes deaths from NO2, which affects lung function and lung development in children and is emitted by diesel vehicles.

The Committee on the Medical Effects of Air Pollutants (COMEAP) is expected to publish figures including deaths caused by NO2 later this year. The combined number of premature deaths caused by vehicle pollution in 2015 could come close to rivalling smoking as the number one cause of premature mortality in the UK, which is estimated to be around 80-100,000 deaths per year.

Following the Supreme Court Ruling, Defra said: ‘We recognise that clean air is vital for people's health and have seen air quality improve significantly in recent decades. Work is under way to ensure compliance with EU NO2 limits – we've invested £2 billion since 2011 to increase the uptake of ultra-low emission vehicles, sustainable travel and green transport initiatives.

'Local Authorities are responsible for improving the air quality in their areas and it is for them to identify the best solution for their area. The government supports these efforts through our Air Quality Grant Scheme and Clean Vehicle Technology Fund.'

The Clean Vehicle Technology Fund has already been used to help many cities tackle the NO2 challenge, although it is clear that more support will be needed if the new plan is to have an immediate impact. For example, provisional allocation of the European Clean Development Fund from 2014 – 2020 covers both air quality and transport – a key area for NO2 reduction.

As both central government and local authorities search for solutions to reduce the level of exhaust pollutants, especially in light of the Supreme Court ruling, we are reminding everyone that there is a cost-effective and immediate way of cutting NO2 from diesel exhausts.

SCRT technology, which combines SCR (selective catalytic reduction) and CRT (continuously regenerating trap), has been shown to reduce NO2 emissions by 96.7%, along with NOX (95%), PM (98.8%), HC (98.1%) and CO (96.5%) in real world operation.

In addition, independent tests which simulate urban bus operation, have also confirmed that SCRT can achieve this reduction. By achieving emissions reductions equivalent to Euro VI when retrofitted to buses as old as Euro III, it means there is no need to buy new vehicles in order to meet new pollution standards. It has already been retrofitted to more than 2,400 buses in the UK and elsewhere in Europe.

Air Quality experts at King's College, London have attributed a 16% reduction in NO2 pollution on Putney High Street to SCRT technology retrofitted to 93 buses.

We upgraded the buses between April and July 2013 and King's College identified a clear decrease in NOX and NO2 concentration during the same period. NO2 concentrations on Putney High Street were well above legal limits before the buses in regular use were retrofitted with our SCRT.

As well as the large drop in kerbside NOX, there was a sustained decrease in NO2 concentrations of 12% (kerb) and 16% (faade) over the full period of the study.

We recently supplied our SCRT system to Brighton Bus for fitting on Euro III buses. The technology was tested against other buses on a route in the city centre that crosses Brighton and Hove through a known air pollution hot spot.

The bus was fitted with Portable Emissions Monitoring System (PEMS) and loaded to represent a 70% passenger load. Multiple trips were conducted in normal traffic during business hours, stopping at regular bus stops in a similar manner to the passenger service.

The research found that, when averaged across the bus route on which tests were taken, the total NOX emissions results of the Euro III bus retrofitted with SCRT were substantially below those of all the other buses tested, including a Euro V hybrid vehicle.

SCRT technology has already been retrofitted to more than 2,500 vehicles, including buses as old as Euro II and III. The focus is now moving to Euro IV and V vehicles.

Many operators invested in these vehicles believing they would help to solve pollution problems but test cycles did not reflect the stop/start reality of urban driving, so many Euro IV and V are not effective in real world urban operation.

The latest advances in SCRT technology means that it is now possible to upgrade these existing vehicles to Euro VI standard at significantly lower cost than buying new. Upgraded vehicles can also meet even tougher standards, such as the new London Ultra Low Emission Zone (ULEZ) limits, which will come into force in 2020.

UK air pollution at a glance

16 UK zones still exceed legal limits for NO2 pollution.
SCRT can upgrade existing vehicles as old as Euro III to the latest Euro VI standard.
SCRT technology can remove 95% of exhaust pollutants.
PM from exhausts is estimated to cause 29,000 premature deaths per year.
Total deaths will be much higher once NO2 figures are published this year.
London Ultra Low Emission Zone (ULEZ) comes into force in 2020. Other cities expected to follow.

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