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Who is responsible for cleaning up the air we breathe?

A blog post by Philippa Oldham

On the 23 January the Institution of Mechanical Engineers launched A breath of fresh air: New solutions to reduce transport emissions. The report brings the discussion of Climate Change (CC) and air pollution into the same forum. It consolidates multiple sources of research into a digestible format, accessible for everyone from academia, industry and government, to those with no scientific background but who have an interest in their health and environment.

With any engineering problem, it is important that we understand the starting position and the size of the challenge, so we can gauge the effectiveness of trials and potential solutions. The consensus between Institution members was that the breadth of this topic was not fully being explored, so the Institution decided to examine the evidence.

Last year 71% of local authorities missed their air quality (AQ) targets indicating that the UK needs a joined-up and new Clean Air strategy to address the problem of AQ and CC. But why should anyone outside of the engineering and political agenda really care about this? Simply the answer is because it is affecting our health and we as individuals are ultimately causing the problem through our insatiable appetite for travel. Transport is responsible for more greenhouse gases (GHG) than any other sector and levels haven’t fallen since 1990.

To address the problem people need to get out of their cars, so investment in public transport is needed, to provide a service that is reliable, cost effective, environmentally sound and accessible to all. The transport network needs to be reviewed holistically so that the whole problem is tackled and emissions are reduced across the spectrum.

For example, every day 8 million passengers pass through UK railway stations however, railway stations are not required to comply with AQ standards imposed by the EU. Enclosed railway stations that support operators that run diesel trains have high levels of air pollution (for example Paddington, Birmingham New Street, Leeds, Manchester Piccadilly, Bristol Temple Meads and Cardiff). Knowing the levels of emission exposure that those using the services and employed within the station is imperative.

The Institution is expecting that feedback on this topic will be that this as a short term problem, with many of these stations benefitting from the scheduled electrification programmes however, some will not. Equally the idea that bi-mode trains offer a solution to routes that have had electrification schemes axed is not true. Bi-mode trains have higher capital and maintenance costs than pure electric trains, and are less powerful when working in diesel mode than when operating on the electrified network and will produce more emissions. Does it really make sense to invest in 30 year assets, powered by diesel technology on the train network while banning diesel from automotive sector?

In terms of road transport, the age of our road vehicles is a challenge as the average has increased, from 6.8 years in 2003 to 7.8 years in 2015. This works against the uptake of new vehicles with greater environmental benefits. For those inseparable from their cars, encouragement is needed to replace with newer low-carbon offerings, potentially making use of scrappage schemes or retrofitting grants.

One of public transport’s great success stories is buses, with two initiatives the Bus Service Operators Grant (BSOG) Low Carbon Emission Bus Incentive and Green Bus Fund. These led to operators refreshing their fleets with lower-carbon solutions and newer vehicles. Through Transport for London (TfL) upgrading their buses to a Euro VI fleet they saw a 90% reduction of oxides of nitrogen (NOx) along the Putney High Street. Freight and logistic operators would benefit from a similar initiative as HGVs represent 21% of surface transport carbon dioxide (CO2) emissions and struggle to decarbonise, due to powertrain requirements and limited scope for electrification.

Discussion into proven solutions that are transferable across different modes of transport are highlighted in the report. Examples include retrofitting exhaust after-treatment technology successfully used on heavy-duty diesel vehicles since the mid-1990s and transferring this to assist with emission abatement technologies currently not typically fitted to ships. This could reduce shipping emissions significantly.

Powering our transport using alternative energy options is another part of the solution. Much publicity and investment has been channelled towards the Electric vehicle (EV) market which offers an answer to the air pollution problem as they have zero tailpipe emissions. However, challenges remain in terms of the source of the electricity to power these vehicles and the sustainability of batteries. Many use rare earth materials, which are sometimes extracted using unethical methods, and it largely remains economically unviable to recycle and breakdown the batteries so that materials can be re-used. Lifecycle analysis must be at the forefront of our discussions, so that future generations are not left with significant complications. This is the aim of the Government’s Faraday Challenge.

Alongside EVs there are Plug-in Hybrids and Hybrids that all make use of co-joined technology of the internal combustion engine, electric propulsion systems and associated batteries. Hydrogen offers a solution that falls in and out of favour due to its challenges with storage, durability, reliability and safety, in addition to cost and supply chain consideration. However, it is being trailed on the rail network by Alstom’s Coradia iLint hydrogen fuel-cell powered trains, expected to enter service next year in Germany, replacing legacy diesel-powered trains.

Due to the time it takes to replenish the fleet of vehicles, alternative low-carbon liquid fuels need to form part of the mix. These include biofuels, which can reduce CO2 and have an impact on reducing particulate matter (PM) and synthetic fuels which due to their manufacturing process produces more consistent and uniform molecules compared to conventional crude oil refining. This improves combustion properties and can reduce air pollutants when used in a standard diesel engine. They are free of unwanted components including sulphur, metals and aromatics, and are nontoxic so less harmful to the environment.

Helping to accelerate and support the development of these solutions are funding competitions, including one that is currently active by the Advanced Propulsion Centre. APC9: Anchoring low carbon technology development in the UK is offering up to £30 million match funding. Successful applications will be R&D projects that can deliver significant reductions in vehicle CO2 or other harmful emissions and have the capability to develop the UK’s supply chain in the field of low carbon vehicle technology.

Congestion is another key issue which is often overlooked in AQ and CC discussions. In nose-to-tail traffic, tailpipe emissions are four times greater than they are in free-flowing traffic. This shows that to address AQ and CC it is not just about getting rid of older, more polluting vehicles but also includes reducing the number of vehicles on our most congested roads.

In the 1950s, doctors kick-started a national movement on the risks of smoking; something similar is needed to address AQ. This education needs to start in the classroom with children who are most vulnerable. Schools should encourage their pupils to use public transport, walk or cycle to school and parents informed not to leave their car engines idling during drop-off and pick-up. Initiatives such as Eco-Schools and the Golden boot challenge are all great to teach our younger generations about their surrounding environment.

In 2017 London introduced a T-charge on those older (higher emitting) vehicles, but what happens to this money? The Greater London Authority should consider re-investing it back into communities and areas where people are most vulnerable for example schools and hospitals by donating pollution absorbing plants, such as bamboo palms, peace lilies and rubber plants or by planting trees and hedges between roads and schools to absorb and disperse pollution.

The Institution recognises that this topic is tough challenge for Government, as air quality and climate change crosses five central departments. However, perhaps we are starting to see a consensus for this following from the joint inquiry on air quality launched in 2017 with four of the select committees combining forces.

But this challenge is so big that we need everyone on board: Government, industry and society at large.