09.45 Dispersion modelling considerations for Net Zero and air quality.pdf

1. Routes to Clean Air, 2023
Routes to Clean Air
10-11th October 2023
Manchester
Catheryn Price

2. Routes to Clean Air, 2023
’ 30 minutes (Assume 25 for talk)
From speaker guidelines:
’ Limit the number of slides. (Average 2 minutes per slides)
’ Recommend 7x7 guidelines – Maximum 7 words per line and 7 lines per slide
’ Pictures tell a 1000 words
’ Avoid Placing text and images at the edges, and avoid extremely bright colours

3. Routes to Clean Air, 2023
Net Zero-related projects and interests – some examples
’ Anaerobic digestion (e.g. flaring, venting emissions, odour)
’ Heat pumps (ambient cooling effects)
’ Energy centres (e.g. NOx emissions, ammonia venting)
’ Fugitive emissions of methane and CO2
’ Carbon Capture:
 Amines emissions and atmospheric degradation products
 Controlled venting of CO2

4. Routes to Clean Air, 2023
Fugitive methane modelling
’ Methane emission quantification using inverse dispersion modelling
 Reviewed and assessed methods, and application to EA-regulated sites
 Compared methods applied to landfill sites
 Recommendations for inverse dispersion modelling approaches
’ Investigating variability in landfill methane emissions using air
quality monitoring data
 Meteorological / operational factors that affect time-varying emissions
 Used statistical and machine learning techniques
 How can data from short measurement periods be extrapolated to
longer periods?
’ CERC involved in two Environment Agency (EA) funded projects on fugitive
methane emissions, with Air Quality Consultants (AQC):

5. Routes to Clean Air, 2023
Glasgow CO2 emission inventory verification
’ CERC involved in project with the University of Cambridge and ACOEM
’ Funded by the Natural Environment Research Council (NERC) and the Scottish
Government
’ Verifying the accuracy of CO2 emissions inventory using ambient measurements
and ADMS-Urban
’ Applied Bayesian-based inversion techniques
’ CO2 data was collected from 15 AQMesh sensors across Glasgow, at 2 m height
 Roadside, urban background and rural sites
 Co-located with existing air quality monitors
 Measured at 1-minute intervals

6. Routes to Clean Air, 2023
Assessment of amine atmospheric degradation products
’ An Environment Agency led project, instigated by the Air Quality
Modelling and Assessment Unit (AQMAU)
’ Main focus is the use of ADMS for assessment - specifically its amine
chemistry scheme
’ Key aims:
 Address the uncertainties of input data and assumptions
 Help users to calculate input parameters
 Improve accuracy of modelling
 Improve transparency and effectiveness of the assessment process

7. Routes to Clean Air, 2023
Assessment of amine atmospheric degradation products
NO2 D NO
O3
•OH
Amines
Nitrosamines
Nitramines
hυ
Reactions
involving
•OH and
NOx
Photolysis
NOx
Emission
of amines
and NOx
Formation of
harmful
products
•OH
NOx
Entrainment of
ambient •OH and
NOx

8. Routes to Clean Air, 2023
Assessment of amine atmospheric degradation products
CH3
CH3
N•
CH3
CH3
N H
•OH
H2O
Amine
Amino
radical
CH3
CH3
N N O
NO
Nitrosamine
CH3
CH3
N N
O
O
NO2
Nitramine
k1a
k3
k4a
k2
k4b
Imine
CH3
CH3
N
O2
NO2
hυ
Jnitrosamine/JNO2

9. Routes to Clean Air, 2023
Assessment of amine atmospheric degradation products
’ Focussed on a specific list of amines (and corresponding nitrosamines
and nitramines): 23+ species
’ Review and collation of reaction rate parameter values: database
created
’ Review of other inputs, e.g. ambient OH concentration effects
 Typical OH concentrations depend on latitude, time of day, etc
’ Investigation of aqueous partitioning parameters
’ Sensitivity tests for key parameters and assumptions

10. Routes to Clean Air, 2023

11. Routes to Clean Air, 2023
Controlled venting of CO2 from carbon capture facilities
’ Releases of pure (or close to pure) CO2
’ ‘Other than normal operating conditions’
’ Times when it’s not possible for the captured CO2 to be processed/
transported as usual
’ CO2 is well known as an asphyxiant but also has toxicity (human health)
effects
’ Stacks/venting need to be designed to protect the public against
potential health impacts
’ Permitting requirements

12. Routes to Clean Air, 2023
Controlled venting of CO2
’ No Environmental Assessment Levels (EALs) or similar thresholds for air
quality impacts of CO2
’ Workplace Exposure Limit (WEL) values (for reference):
 8 hour: 5000 ppm (0.5%)
 15 minute: 15,000 ppm (15%)
’ Ambient background levels are 420 ppm (0.042%)

13. Routes to Clean Air, 2023
Controlled venting of CO2
’ Controlled releases of CO2 via tall stacks
’ If releases are entirely in the gas phase and not complex (at ambient pressure
at release) then much more straightforward than emergency releases
’ Gaseous CO2 is dense
 But released at height
 ADMS can model elevated dense gas
releases, if no longer dense when they reach
the ground
 Inbuilt checks for plume density at all times

14. Routes to Clean Air, 2023
Controlled venting of CO2
’ Validation – limited datasets for venting
’ Historically, experiments have tended to focus on uncontrolled releases
’ Need robust data for validation
’ In the meantime:
 Comparison of output from different types of model – e.g. ADMS vs GASTAR
 Sensitivity tests
 Investigation of plume properties: trajectory, density,
 Including ‘worst case’ scenarios

15. Routes to Clean Air, 2023
Summary
’ Covered just a few examples of air quality and dispersion modelling Net Zero
topics
’ There are some new challenges for dispersion modelling
’ But there are well-established ways of dealing with these challenges,
including:
 Validation
 Sensitivity testing
 Exploring worst-case scenarios
 Transparency
 Knowledge sharing