Ammonia creation and conversion technology cleans up diesel

In an era of increasingly strict emissions regulation, ammonia creation and conversion technology (ACCT) extends the operation of selective catalytic reduction systems to low-temperature exhaust conditions

Collaborate To Innovate 2017
Winner: Emissions technology for cleaner diesel engines
Partners: Loughborough University; Caterpillar; Energy Technologies Institute; Johnson Matthey

The toxic cocktail of tailpipe emissions has been closely regulated since 1993, when the EU introduced Euro 1, a set of mandatory standards designed to put OEMs on the road to cleaner vehicles. In the space of 24 years, increasingly stringent standards have led to reductions in the permissible limits for carbon monoxide, hydrocarbons, particulate matter (PM) and oxides of nitrogen (NOx), while ongoing efforts seek to further reduce their impact.

At a regional level, London is seeking to redress the situation with the introduction of a T-Charge (or Emissions Surcharge), which requires drivers of pre-Euro 4 cars to pay £10 to travel to the city’s central zone. According to the Mayor of London’s office, 7.9 million Londoners – nearly 95 per cent of the population – live in areas exceeding the World Health Organization guidelines on toxic air quality particles (PM2.5), and air pollution contributes to thousands of premature deaths in the capital each year.

ammonia creation and conversion technology

In July 2017 the UK government announced plans to improve air quality – and, by its calculations, recoup billions of pounds in lost productivity – by tackling roadside concentrations of nitrogen dioxide. One of the ways it will do this is by ending the sale of all new conventional petrol and diesel cars by 2040. The government acknowledges that Britain is among 17 EU countries in breach of annual targets for NO2, but it lays some of the blame – with a degree of justification – at the same European testing regime that sought to curb harmful emissions.

The focus on cars, however, overshadows the regulations as they apply to other modes of on- and off-road vehicle. In 2014, European Regulation UN ECE 595/2009 brought in the Euro 6 standard for heavy-duty diesel engines, reducing the limit for NOx emissions by 77 per cent, while continuing to set challenging limits for the control of other gases and particulates. According to Transport for London, the test protocol changed to broaden the range of speed/load conditions for which an engine had to meet the emissions limits. Additionally, an ammonia (NH3) concentration limit of 10ppm now applies to diesel and gas engines, which was introduced to control ammonia slip from selective catalytic reduction (SCR) systems used to control NOx emissions.

However, by the time Euro 6 was introduced in January 2014, a public-private partnership was already more than a year into a project aimed at ensuring the viability of on-highway vehicles and heavy-duty diesel vehicles (HDVs) in an era of increasingly strict regulation. The effort marked the first collaboration between Loughborough University and the Energy Technologies Institute (ETI), which commissioned the project as part of its Low Carbon Heavy Duty Vehicle (HDV) Programme. ETI’s focus on HDV efficiency was prompted by the limited options for low-carbon fuel alternatives for HDVs, plus the fact that the proportion of CO2 emitted by HDVs would continue to rise relative to other sectors. The HDV programme – incorporating land, sea and rail vehicles – identified efficiency as the most cost-effective way of reducing emissions and set a target to improve HDV efficiency by 30 per cent.

As part of the overall project, UK-based specialist teams from ETI member Caterpillar and Johnson Matthey have worked on novel SCR technology to help achieve the 30 per cent target and 3-4 per cent fuel-efficiency improvements.

Research at Loughborough has further improved SCR, with the development of its own ACCT (ammonia creation and conversion technology), a highly novel device that extends the operation of SCR to low-temperature exhaust conditions. As well as lowering NOx, ACCT could deliver fuel savings. Loughborough’s Prof Graham Hargrave developed the technology with research associate Jonathan Wilson.

In May 2017 Hargrave said that many engines – such as those used on buses and construction vehicles – never reached the optimal temperature required for SCR systems to operate efficiently because of the stop/start nature of their journeys. The SCR systems themselves treat NOx emissions with AdBlue, which provides the ammonia required to reduce NOx into nitrogen and water. According to Loughborough University, AdBlue functions well only when temperatures exceed 250ºC, so the SCR does not necessarily operate in all engine conditions, such as stop-start commutes. Similarly, at lower temperatures the use of AdBlue can result in severe exhaust blockages and subsequent engine damage.

The ACCT technology, a world first, has been tailored for HGVs but the same system is fully scalable for use in all diesel vehicles. More broadly, the project has delivered 21 innovation notifications, seven patents and a series of new models for after-treatment design. The patents include the SCR after-treatment injector/mixer concept, the exhaust architecture, new sensors and novel control approaches.

A further patent has been submitted under the Green Channel accelerated scheme for ACCT. According to Loughborough marketing manager Anna Leather, the overall project presented a range of challenges, not least the need to strike a balance between the interlinked requirements for legislation relating to NOx emissions and CO2 reduction, lower fuel consumption and engine efficiency for the consumer, and the performance and cost concerns of the manufacturer. The project therefore required a multi-disciplinary approach in which each partner was assigned key reporting responsibilities alongside their expertise. Individual responsibilities were also assigned within the control system, catalyst and applied research teams, with an agreement to share key decisions as each parallel work package progressed to inform the next project phase. This resulted in it being delivered on time, in budget and meeting legislative, consumer and manufacturing requirements.

With the project now entering the exploitation phase, the ETI’s influence in engaging government and industry is crucial to the rollout of this groundbreaking technology. It is also engaged with several OEMs that may wish to exploit the technology, including the ACCT device, for on-highway application.

As first adopter, Caterpillar has produced a demonstrator vehicle to showcase the efficiency improvements for the off-highway HDV application.

The potential environmental, societal and economic impact of this project is significant given that trucks, buses and coaches produce about 25 per cent of CO2 emissions from road transport in the EU, and some 5 per cent of the EU’s total greenhouse gas emissions.

Shortlisted – Transportation

Project name: Air Products’ cryogenics expertise supports world’s first refrigerated truck cooled by liquid-nitrogen engine
Partners: Sainsbury’s; Air Products; Dearman

The global market for refrigerated transport is predicted to double by 2025, but growth comes at an environmental cost with cooling accounting for 7 per cent of global greenhouse gas emissions. This figure is projected to double by 2030, and the problem is exacerbated by refrigerated vehicles that emit grossly disproportionate amounts of toxic pollutants. To counter this growing problem, Air Products and Dearman created the first refrigerated vehicle to be cooled by a liquid-nitrogen powered engine. In doing so, they have demonstrated the commercial viability of solving pressing environmental challenges. By displacing diesel engines, the collaboration’s solution reduces life-cycle CO2 emissions
by up to 85 per cent and cuts total engine emissions by up to 90 per cent.

The system has been on trial at Sainsbury’s, where 1.6 tonnes of CO2 was saved, which is the equivalent of driving for more than 14,500km in a modern family car. Similarly, the trial saved 37kg of nitrogen oxides and 2kg of particulate matter compared to a similar diesel system. The trials to date bring delivery vehicles cooled by liquid-nitrogen powered engines one step closer to becoming a commercial reality, offering a viable alternative to diesel engines. The uptake of the trial by Sainsbury’s should help to encourage the rest of the sector to follow suit.

Project name: East West Rail Phase One
Partners: Chiltern Railways; Network Rail; Carillion Buckingham Joint Venture; Atkins; Siemens; RSK

The Bicester to Oxford Collaboration has been acknowledged by C2i for delivering Chiltern Railways’ Oxford-to-London service and the first phase of the East West Rail programme (EWR1). Multiple deliverables ­– including the first rail connection from a major British city to London in over 100 years via a cord line – were achieved through a combination of technical design excellence and digital engineering, with collaboration between client, designer and contractor. EWR1 was commissioned to rehabilitate a 16km section of railway, between Oxford and Bicester, from a single-track branch line to a modern, 100mph (161km/h) twin-track railway.

The scheme’s premise was to connect Oxford to London Marylebone station, but it has since grown to become an essential part of the wider East West Rail programme. This meant the project transformed from a £130m Chiltern Railways-funded scheme to a £320m effort co-financed with Network Rail. This necessitated the opening of communications channels with the affected local authorities and their representatives. Hence it was paramount to the success of the project to establish the right mechanisms to maximise collective performance. The Bicester to Oxford Collaboration is made up of Chiltern Railways, Network Rail, Carillion Buckingham Joint Venture, Atkins, Siemens and RSK.

Project name: Rolls-Royce University Technology Centre in Combustion System Aerothermal Processes
Partners: Loughborough University; Rolls-Royce

The Loughborough-based Rolls-Royce University Technology Centre in Combustion System Aerothermal Processes is conducting industry-driven research that aims to deliver innovative technologies for current and next-generation low-emission gas turbine engines. The combustion systems of gas turbines consume large quantities of fuel that are burnt at high temperatures and pressures, and the UTC-RR partnership has consistently addressed ways in which such systems can be made ‘leaner and greener’.

A fitting testimony to the UTC-RR partnership was demonstrated in 2016 when the government announced plans for a new £15m National Centre in Combustion and Aerothermal Technology to be based at Loughborough. In keeping with the collaboration’s ambitions, the centre will focus on the development of future low-emission aerospace combustion systems designed to reduce the environmental impact of aircraft.