Key technologies to reduce air pollution

Key technologies to tackle air pollution can include lower emission vehicles (including electric, hybrid and LPG), car sharing, and lower emission sources of heat and power. Whilst the role of these technologies in reducing air pollution is generally accepted, there are also numerous other emerging technologies which could also play a role in the future. Here is a selection of these technologies:

Gas to Liquids

One solution to tackle emissions from diesel vehicles is to switch to alternative fuels. Whilst electric and LPG offer completely separate fuel systems, there are also other options which offer the potential to clean up existing diesels. For example, Shell has developed a new synthetic “gas to liquid” (GTL) fuel derived from natural gas which is a “drop in” replacement for diesel (i.e. the engine requires no modification). Testing has shown that the use of GTL in heavy duty vehicles such as trucks, buses and ships could reduce Nitrogen Oxide (NOx) emissions by 5-37%, and Particulate Matter (PM) emissions by 10-38%, depending on the vehicle age. GTL fuel is already being produced in significant quantities globally, and is available commercially in the Netherlands, but its use is currently very limited in the UK. Similarly, natural gas can also be converted into dimethyl ether (DME) – another potential alternative to diesel. It is thought that the use of DME reduces NOx emissions by around 25% (compared to a standard diesel), and virtually eliminates PM emissions.  DME is less straightforward to implement than GTL in the sense that it requires some engine modification, although manufacturers such as Ford and Volvo are apparently investigating the potential to bring vehicles to market which use DME as a fuel.

Hydrogen Fuel Additives

Reductions in emissions can also be achieved by improving the fuel combustion cycle in existing vehicles through the use of additives. The ezero1 technology produced by UK developer CGON does this by feeding small amounts of hydrogen into the vehicle air intake such that it creates a more efficient burn. Independent tests show that this increases fuel efficiency, whilst reducing emissions of NOx, PM, Hydrocarbons and Carbon Monoxide. The technology can be retrofitted to existing cars and vans (petrol or diesel) and is available commercially, although to date has only been sold in relatively small numbers.

Autonomous vehicles

One of the mega-trends in the automotive sector is the move towards autonomous vehicles or “self-driving cars”.This could fundamentally change the way that vehicles use the road network, reducing the stop-start nature of traffic (which is partly caused by the way that we humans drive cars), and opening up the possibility of “vehicle platooning” on motorways. A range of studies have estimated that autonomous vehicles could improve fuel efficiency by 15-40%, reducing emissions of local pollutants as well as greenhouse gases, not to mention the benefits in terms of safety and congestion. Volvo has launched plans to trial driverless cars in London by 2017, whilst the 2016 Budget also contained a number of measures to promote connected and autonomous vehicles.

Liquid air

New technologies are also being developed to address very specific sources of pollution. For example, a growing source of pollution in cities comes from refrigerated vans and trucks. It has been estimated that there are around 84,000 transport refrigeration units on the road in the UK, each of which emits 29 times as much PM and six times as much NOx as a modern truck. Whilst trucks are subject to emissions standards, the auxiliary engines used to power refrigeration units are largely unregulated and are highly polluting. Technology company Dearman is developing an alternative system based on the use of “liquid air”, which produces zero emissions on the road.

Photo-catalytic materials

An alternative to cleaning up emissions from vehicles directly could be to deploy technologies which remove pollution from the ambient air. For example, a number of companies are developing photo-catalytic treatments which remove pollutants from the air in the presence of sunlight. These treatments can be applied to a range of surfaces, for example roofing tiles, roofing felt or even the surface or roads. A recent report by the Environmental Industries Commission suggested that applying photo-catalytic treatment to roads is amongst the cheapest options to reduce PM and NOx pollution, although it acknowledged that further trials of the technology would be required to understand its potential. However, contrary to this, a recent report for Defra found “no compelling evidence” that the use of these treatments would actually reduce NOx pollution.

Air purification

Developers are also looking at other ways of cleaning air in urban environments. Studio Roosegarde, a Dutch design company, has developed the “Smog Free Tower” – an air purifying tower which sucks in pollution and expels clean air. The extracted pollution is, somewhat bizarrely, turned into pieces of jewellery. The first tower has been installed in Rotterdam (paid for by a kickstarter campaign), and the designers claim that a single tower could clean 3.5 million cubic metres of air per day. They plan to roll out the smog free towers across other global cities.

Green infrastructure

The role of vegetation in mitigating the effects of air pollution has been highlighted as one of the potential benefits of urban green space. Trees in urban green space can influence air quality in a number of ways; for example through direct absorption of gaseous pollutants and interception of particles onto leaf surfaces, by lowering air temperatures through transpiration which can reduce the formation of ozone, and through the direct production of oxygen during photosynthesis. The overall success of green infrastructure is still widely debated, but a potential solution which should not be left out.

Extract edited from: ‘6 New Technologies Which Could Improve Urban Air Quality‘, Richard Howard, Policy Exchange, 2016