18 Jun 2024Source apportionment analysis for London’s bus fleet

The Transport for London (TfL) red-liveried bus fleet are part of the city's identity, but were a key area for improvement in the Mayor of London's 2018 Environment Strategy. Southwark Borough Council commissioned CERC consultants to assess the contribution of bus emissions to total pollutant concentrations in Southwark.

Using the ADMS-Urban model and emissions inventory tool EMIT, we created air quality maps of the borough for nitrogen dioxide and particulates, based on all emissions and then on bus emissions only. We also modelled pollutant concentrations at a large set of roadside receptors along Southwark's bus routes.

We took traffic data from the London Atmospheric Emissions Inventory, using EMIT to create a traffic scenario including only buses. The figure shows source apportionment results for NO_x, with concentrations due to bus emissions shown as a proportion of the concentration from all emissions sources.

At locations where the modelled annual average NO₂ objective is exceeded, buses may contribute to less than 10% of the total NO_x, as seen along Old Kent Road. In contrast, at Elephant Square and St. George's Circus, buses can be responsible for over 40% of total NO_x. This highlights key areas where improving bus infrastructure would result in tangible improvements to air quality.

15 May 2024ADMS 6.0.2 released

CERC are pleased to announce the release of ADMS 6.0.2. This is a minor update providing additional output options that were requested at the 2023 ADMS User Group Meeting.

The first of these new options is the ability to output additional plume properties for point sources to the .cen file. The plume density and Richardson number used in the plume rise calculations can now be output, which can be useful when examining the behaviour of elevated dense releases. Additionally, wind speed and turbulence values at the mean plume height can now be output allowing for greater understanding of the behaviour of the plume.

The other new output option is the ability to output the accumulated horizontal concentration flux at specific locations. This output is given per wind direction sector making for easy comparison with measurements obtained from directional passive air samplers.

In addition to these new output options we have decreased run times for runs with spatially varying deposition. For full details on the changes within ADMS 6.0.2 please see the What's New document.

ADMS 6.0.2 is available to download from the User Area for licence holders with current support.

3 May 2024Air quality assessment of amine-based carbon capture

The Environment Agency commissioned CERC to carry out a project instigated by their modelling team AQMAU, entitled Improving Post-Combustion Carbon Capture Air Quality Risk Assessment Techniques. The project aimed to increase confidence in risk assessments for regulatory purposes, to integrate practical tools and evidence, and to inform decision-making.

The decarbonisation of industry is pushing the evolution of air dispersion modelling to assess the risk of emissions from emerging techniques such as amine-based post-combustion carbon capture.

As developers of the state-of-the-art ADMS amines chemistry module, CERC were ideally placed to carry out this project and have published their report.

The project addresses the uncertainties of ADMS input data and assumptions and improves the transparency and significance of the assessment process. It will further increase confidence and understanding of the ADMS approach and assessment strategies.

As part of the project, CERC developed an additional user-friendly tool and user guide to help model users calculate and document the amine-related input parameters.

2 May 2024Booking is now open for the ADMS User Group Meetings, 4-5 December 2024, Cambridge

You can now book your tickets for the 2024 ADMS User Group Meetings, which will be held at Murray Edwards College on 4th and 5th December.

• ADMS 6 User Group Meeting, 4th December
• ADMS-Urban and ADMS-Roads, 5th December

The annual ADMS User Group Meetings are a great opportunity to hear the latest ADMS model news and advice from CERC consultants and model developers, to hear talks by model users about their own applications of the software, and to network with other model users.

Tickets are available to order through Eventbrite until 23:30 on Tuesday 12th November. Organisations with a valid software support contract are entitled to one or more tickets free of charge depending on the type of licence held. The draft programme will be published soon.

29 Apr 2024Air quality impact of paint spraying facilities

CERC has carried out assessments of the air quality impact of exhaust plumes from vehicle and aircraft paint spraying facilities to support planning applications, using ADMS 6.

CERC's consultancy team worked from a list of paint products, together with Safety Data Sheets and Technical Data Sheets for paint components. These were combined with paint usage data and Emission Limit Values (ELVs) to calculate emission rates of particulates, VOCs and isocyanates from spray booth exhaust stacks.

Process-specific ELVs are provided in Defra Process Guidance Notes such as 6/47(11): Statutory guidance for original coating of road vehicles and trailers.

The Guidance Note 6/47(11) refers to the calculation of a suitable stack height using HMIP Technical Guidance Note (Dispersion) D1, now obsolete. The Note states that alternative dispersion models may be used.

We have found that the application of ADMS can lead to the calculation of a lower stack height than screening methods such as D1, especially where working hours are represented.