Seeing through the big smoke?

27th October 2017

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  • Transport



Although road transport is a major source of air pollution, public transport has a key role as part of the solution. Andrew Clark reports.

The significant health impacts of pollutants such as particulate matter (PM) and nitrogen oxides (NOx) are increasingly well documented. As these pollutants result from the combustion of petrol and diesel, air quality is a key issue for the public transport sector, which has traditionally been powered largely by diesel.

This is particularly true of road transport, which has been the focus of recent UK government plans to improve air quality in our towns and cities. It’s important to note, however, that public transport is a net contributor to solving these issues. By reducing the number of vehicles, especially private cars, on the road, mass transit reduces emissions from travel and their impact on public health and the environment.

This point that public transport is part of the solution is crucial as policymakers design ways to reduce emissions from transport, and encourage behaviour change.

Recent research in the UK by Greener Journeys demonstrated that a Euro VI-rated diesel car emits 10 times as many per-passenger NOx emissions as a Euro VI-rated diesel bus. And a double-decker bus could take up to 75 cars off the road, at a time when the Department for Transport reports that the number of cars on England’s roads is rising by over half a million every year. Without buses, urban congestion in city centres would be 21% higher at peak times, with air quality significantly worse as a result.

Vehicle technology

Reducing local pollutants has been the main driver of bus technology innovation for the past few decades, primarily through implementation of new ‘Euronorm’ standards for diesel vehicles across Europe.

Recent standards drastically reduce emissions of NOx and PM, and are also rigorously tested, validated and upheld – in contrast to recent scandals around widespread breaches of emissions standards in diesel cars.

In addition, new technologies and alternative fuel types that further reduce environmental impact are emerging. Electric vehicles, with zero-tailpipe emissions, have the potential to significantly reduce air pollution. However, they also bring a raft of new challenges, including operational range, battery technology risk and capital cost, which can be twice that of a conventional diesel bus.

The best way to fund and provide the necessary vehicle charging infrastructure – and associated energy demand – is also yet to be fully understood. There are multiple options when it comes to charging technology, from the ‘plug-in’ single charge solutions common among electric cars, with charging points located in bus depots, to ‘opportunity’ charging solutions located at strategic points, such as bus stops or bus stations. An opportunity charge solution can use either inductive or conductive technology.

New fuels

While electric buses will form an integral part of future European bus fleets, other technologies will also have their part to play. Gas buses, which can be fuelled with biogas and typically have lower PM and NOx emissions than even a Euro VI diesel bus, are an option, particularly in locations with abundant gas supply and existing infrastructure.

Other liquid fuels such as biofuels are also being increasingly used, although primarily this is to reduce carbon emissions.

Recent amendments to the Renewable Transport Fuel Obligation will accelerate the use of such fuels in the UK, by requiring transport fuel suppliers to deliver an increasing proportion of renewable fuel. This will be ramped up from today’s 4.75% to 9.75% by 2020 and 12.4% by 2032, with a focus on biofuel from waste.

With international and national policy and vehicle technology developing fast, it is clear that a mix of technologies will be necessary. One size will not fit all for the diverse mix of long-distance, inter-urban and urban bus operations across the UK and Europe.

What is clear, though, is that public transport will continue to be part of the solution to tackling environmental and social challenges arising from global travel.

Arriva: Driving change (Case Study)

As a public transport provider, protecting the environment is an inherent part of Arriva’s culture.

We recognise the key role transport services have to play in addressing environmental challenges – one that will grow in importance in a world of population growth, urbanisation and resource scarcity.

Our commitment is to continually reduce the impact of global travel by accelerating a shift to shared mobility, while minimising our own environmental impact as a business. To bring this to life, in 2015 we launched an Arriva-wide environmental strategy; our Journey to Destination Green.

Air quality is an extremely high-profile issue for our business. A strategic theme of Destination Green is fuel, with an increasingly important focus on reducing local air pollution. As well as working closely with authorities to tackle congestion and improve air quality through public transport provision, we are committed to reducing emissions from Arriva’s own fleet. In the UK, the average emissions produced by an Arriva bus reduced by over 50% for PM and 40% for NOx between 2010 and 2016, as we have invested heavily in cleaner Euro VI vehicles alongside emerging technologies such as electric vehicles.

We began operating London’s first all-electric bus line in 2014, and are operating an innovative trial of inductive, opportunity charging electric buses in Milton Keynes. During 2017, we will introduce over 470 new buses in the UK, all of Euro VI standard, hybrid, gas or electric.

We are also rapidly increasing our capabilities and understanding of electric vehicles across Europe, operating a steadily increasing number, for example, in the Czech Republic, Netherlands and Slovakia. While electric buses are an integral part of our fleet strategy, other technologies play their part. We currently operate gas buses in a number of countries, including Denmark and the UK, and in Sweden our entire bus fleet is run on biofuel. We’re working hard to raise awareness of air pollution and to encourage understanding, use and support of public transport as part of the solution.

Our UK bus business participated in National Clean Air Day this year. For example, in the Midlands we led a campaign including sessions in local schools. Pupils created posters showing key facts, the best of which were displayed on board our buses.

While it is important to celebrate successes, we are looking firmly to the future to fully understand the new technologies and business models emerging to deal with issues such as air pollution, and provide the best solutions for customers.

Andrew Clark is head of environmental sustainability at Arriva


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