IAQM/EPUK Planning Guidance, How well is it working for you? Discussion Meeting 15.07.16

1. Treatment of Small CHP Plant
and Short-term Use Diesel
Generators in the IAQM
Planning Guidance
Dr Ben Marner

2. Overview
• Small CHP can have significant impacts
Significant sources are being screened out in the
current guidance
• Diesel generators which aren’t used for long can
have significant impacts
But they are often ignored in assessments
Made using recycled slides

3. IAQM Screening Criteria

4. Comparison of Some NOx
Emission Sources
Google

5. ‘Dispersion’ Criterion
Google
Earth

6. Micro CHP Case Study
2 x 5.5 kWe (20kW fuel input) CHP
 25.5 m tall building
 27 m high flue
 Modelled using ADMS
 CHPs add 0.7 µg/m3 annual NO2
 ‘Moderate’ Impact
 Background NO2 is >40 µg/m3

7. Solution for CHP?
• Suggested “precautionary” criterion of 15kWe
• Alternatively tighten up ‘dispersion criterion’
But it would be very difficult to make this sufficiently
definitive

8. Short-term Use Diesel Generators
• Short-Term Operating Reserve
• Mobile Plant
 e.g. construction sites
Temporary but used intensively
• Backup reserve / life safety
power cuts / fires
Regular routine tests – often 20
mins 1h each month

9. Diesel Generators

10. Diesel Generators
60 MW (fuel input)
(20 MWe) bank of
generators
60 km of M25

11. Generator Case Study
• Bank of 20 x 3MVA backup generators
 12 hrs of testing per year (grew to 24 hrs)
 IF testing coincided with worst-case met:
 PC to 99.79th percentile of 1-h NOx = 4,086 mg/m3
 PC to annual mean NOx = 13 mg/m3
 Assessed the probability of significant impacts
 Could not discount potential for significant impacts

12. Solution for Generators?
• Suggested Addition to Paragraph 6.20 J
“Description of construction phase impacts. These impacts will relate
primarily to dust emissions, which give rise to dust soiling and elevated
PM10 concentrations, although construction vehicles and plant and
vehicles may need assessment; particularly if diesel power
generators are to be used.”
• Suggested New Paragraph for Section 6
“When considering standby generators that are present
only in case of power failures or emergencies,
consideration should be given to any routine testing
procedures. Even operation for a few hours per year
can give rise to impacts that should be assessed”

13. Summary
• Please can we have more stringent criteria for
CHP?
• Please can we encourage robust assessments of
diesel generators?

14. Head Office
23 Coldharbour Road, Bristol BS6 7JT
Tel: 0117 974 1086
London Office
12 Airedale Road, London SW12 8SF
Tel/Fax: 020 8673 4313