Categories
Mobility

5: Go-Ahead • vehicles that filter air as they drive

Problem:

Construction, industrial and vehicle-generated PM10 (Particulate Matter) contribute to life-shortening cardiovascular illnesses and respiratory diseases.

Solution:

To mount various types of air purifiers onto circulating vehicles. In September 2018, Bluestar, one of the UK’s largest bus operators launched the country’s first air filtering bus prototype in an effort to tackle air pollution in the city of Southampton.

They chose one of their low-emission Euro VI buses, each of which produces no more than 0.08g/km of nitrogen oxide.

The filter, designed and manufactured in collaboration with PALL Aerospace, headquartered in Port Washington, New York, the world’s largest aerospace and defence filtration company, is made in an engine barrier-type filter construction and designed to remove up to 99.5% of particles from the air without any impact on the passenger or travel experience.

Southampton was chosen as the location for the pilot following a 2018 World Health Organisation (WHO) report, which warned that the city was at the limit of unsafe air pollution.

From September 2018, running for 100 days, covering 9,000 miles (14,500 km), the pilot bus was able to clean 113 million cubic ft. (3.2 million cubic m.) of the city’s air, the equivalent to the volume of 1,288 Olympic swimming pools.

The air filter took in 35 cubic feet (1 m³) of air per second meaning that in one hour it was filtering the same volume of air as 6,000 people breathing.

It extracted PM10 weighing a total of 65g – roughly the same as a tennis ball – over the course of the trial. Encouraged, Bluestar decided to retro-fit an additional five buses on the number seven route serving Lordshill and Sholing via the general hospital, Millbrook, Shirley, City Centre and Woolston.

While a single bus has the capacity to clean the air on its route every 215 days, to a height of 33 ft. (10 m), it would take just nine days for the newly expanded fleet to achieve the same target passenger capacity and remove as much as 2.8 lb (1.25kg) of PM10 from the air every year.

Further encouraged, from summer 2020 “breathe Bluestar” introduced the technology to Oxford, Plymouth, Newcastle, Manchester, Crawley/Brighton.

A further five buses were also brought into service in Southampton. If the air filter were to be deployed on 4,600 buses across the UK, it could remove as much as 2,425 lb (1,100 kg) of PM10 particles every year.

In parallel, Bluestar also fitted a total of 19 vehicles with solar panels, one of them fitted with the air filter to see whether solar energy could be used to make the filter completely self-sufficient. (www.bluestarbus.co.uk)

Shivom Sharma and François Maréchal at the Industrial Process and Energy Systems Engineering group, EPFL in Zurich had patented a concept which involves capturing CO₂ within the exhaust system of a truck, converting it into a liquid and storing it on the vehicle.

The liquid CO₂ would then be delivered to a service station where it will be turned back into fuel using renewable energy. The system could theoretically work with all trucks, buses and even boats, and with any type of fuel.

The advantage of this system is that it can be retrofitted to existing vehicles in order to neutralize their impact in terms of carbon emissions. (epfl.ch/labs)

In terms of private transport, automobile manufacturer Hyundai has developed the NEXO hydrogen fuel cell automobile with an advanced air purification system capable of filtering 99.9% of very fine dust.

As a test, they teamed up with University College London (UCL) to take on London’s dirtiest driving route, which includes areas such as Kings Cross, Westminster, Elephant and Castle, and Deptford.

Hyundai claims that if just one NEXO is driven for an hour, it has the potential to purify 59 lb (26.9 kg.) of air, which it says is the same amount as 42 adults breathe in 60 minutes. The car producer also claims that if there were 10,000 NEXOs on the road it would subsequently have a carbon-reducing effect akin to planting 60,000 trees. (hyundai.com)

Other schemes in South Korea and China are also working on air purifying transport. And in Thailand there is also work on an air purifying bike.

In Rotterdam, the Netherlands, Studio Roosegaarde’s Smog Free Project has teamed up with China’s largest bike-share company Ofo, to develop a Smog Free Bicycle with a dual function: not only does it offer transport on two wheels and ease traffic congestion, it also cleans smog.

Through a device mounted on the handlebars, polluted city air is drawn in through vacuum suction while the bicycle is in motion. As the air passes through a filter, it is cleaned of harmful particles and purified, literally giving the cyclist a breath of fresh air.

Dan Roosegaarde often takes his inspiration from biomimicry for his innovative eco-friendly projects. The Smog Free Bicycle was inspired by the manta ray, the large flatfish which has a unique filter system of pores that acts as a sieve for the plankton it feeds on, while expelling the purified seawater through its gills.

The plan is to launch an initial 300 bicycles. There is interest in cities such as London, Paris and Luxembourg as part of their bicycle-sharing programs. (.studioroosegaarde.net)

Together, fleets of buses, automobiles, electric and pedal bicycles, all fitted with air filtering systems could certainly make a contribution to planet protection.

Shivom Sharma and François Maréchal, “Carbon Dioxide Capture From Internal Combustion Engine Exhaust Using Temperature Swing Adsorption” Frontiers in Energy Research, 16 December 2019.

Discover solution 6: a machine that recycles soot to make printing ink

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