Appendix
Environment Enterprise and Transportation Committee
26th August, 2010
Agenda Item No. 14
MOSSMORRAN & BRAEFOOT BAY
INDEPENDENT
AIR QUALITY MONITORING REVIEW GROUP
2009 Annual Report
August 2010
CONTENTS
1.
INTRODUCTION
2.
OBSERVATIONS
3.
CONCLUSIONS
APPENDIX 1
The Review Group: Constitution and Terms of Reference
APPENDIX 2
Membership of the Review Group
APPENDIX 3
Regulatory and Policy changes relating to air quality in
2009
APPENDIX 4
Regulated emissions to air in 2009
APPENDIX 5
2009 flaring report
APPENDIX 6
Atmospheric modelling Study at ExxonMobil Fife
Ethylene Plant Mossmorran
APPENDIX 7
Glossary
MOSSMORRAN & BRAEFOOT BAY INDEPENDENT AIR QUALITY
MONITORING REVIEW GROUP
2009 Annual Report
1. INTRODUCTION
The Mossmorran & Braefoot Bay Independent Air Quality Monitoring Review Group (the
Review Group) was formed to provide advice and recommendations to Fife Council (formerly
Fife Regional Council and Dunfermline and Kirkcaldy District Councils) regarding the
monitoring of air emissions arising from the operations at the Mossmorran plants and the
Braefoot Bay terminal facilities (operated by Shell UK Limited and ExxonMobil Chemical
Limited). The constitution and terms of reference of the Review Group are described in
Appendix 1. Appendix 2 lists the members of the Review Group during 2009.
Shell UK operates the Mossmorran Gas Fractionation Plant that extracts natural gasoline,
ethane, propane and butane from natural gas liquids pumped from the St Fergus gas plant
at Peterhead. The plant at Mossmorran comprises three identical process units fed directly
from the pipeline. Large atmospheric pressure tanks store propane, butane and gasoline.
These products are supplied by underground pipeline to the Braefoot Bay deep water
loading facility, where they are loaded on to tankers. Ethane is piped to feed the Fife
Ethylene Plant (operated by ExxonMobil) and to the Inneos site at Grangemouth. The plant
also supplies approximately 5% of the total propane and butane to the adjacent Shell Gas
Road Loading Terminal. The ExxonMobil Chemical Fife Ethylene Plant is one of Europe's
largest and most modern ethylene plants. It has the capacity to produce 830,000 tonnes of
ethylene a year.
Previous air quality monitoring demonstrated that concentrations of benzene and other
hydrocarbons were low in the vicinity of the facilities. The Review Group concluded in 1999
that its work was nearing completion and that further air quality monitoring was probably not
required. However, the Review Group was reconstituted in 2001 following concern
expressed by local communities, and highlighted in media reports, with regard to perceived
air quality and cancer-related health issues in the vicinity of Mossmorran and Braefoot Bay.
The Review Group continues to liaise with local communities and representatives of the local
health service.
The aims of this Annual Report are to:
Outline any substantive changes in the facilities at Mossmorran and Braefoot Bay
and their likely impact on local air quality;
Describe any changes in air quality regulation and changes in knowledge on health
effects of benzene or any other possible emissions from the plants;
Comment on the emissions from point sources at the facilities;
Summarise the available data on flaring during 2009;
Review modelling studies that were undertaken to assess the impacts of flaring at the
Mossmorran plant on local air quality; and
Note the potential impact of planned wind turbines at Little Raith on pollutant
dispersion from the Mossmorran site.
2.
OBSERVATIONS
The main observations of the Review Group in 2009 were as follows.
i)
There were no significant changes in the plant or its operation during 2009. The
replacement of the control room at the Fife Ethylene Plant was completed which will
ensure the continued smooth running of the plant. Both Exxon Mobil and Shell are
continuing to invest in their Mossmorran plants with a view to these plants operating
for at least a further 20 years.
ii)
There have been no changes in the regulations governing air quality management
and the prevention and control of emissions to air. The revised Technical Guidance
for local authorities in relation to Local Air Quality Management was issued in 2009
but this has no implications for the operations at Mossmorran and Braefoot Bay
which are regulated by the Scottish Environment Protection Agency (SEPA). Some
regulatory changes are possible during 2010 (Appendix 3).
iii)
Emissions from all regulated sources at the Mossmorran and Braefoot Bay facilities
in 2009 were within the emission limits set by SEPA (Appendix 4). Emission limits are
set to ensure that the impact of emissions are minimised through the efficient
operation of a process. As it can be difficult to monitor a substance once it has been
released into the atmosphere, operators are required to carry out periodic
measurements of gases before they exit the stacks. Emission Limit Values (ELVs)
are specified in a Permit or Authorisation and relate generally to the principal
emissions from industrial processes where control is necessary. ELVs can be a direct
requirement of legislation, set in connection with what is achievable in terms of Best
Available Techniques, or be generated on a site specific basis. ELVs are set for the
protection of human health and the environment.
iv)
The total quantities of gas flared in 2009 were lower than those flared in each of the
three preceding years, although there was an increase in the quantity of gas flared at
the Shell site (Appendix 5). Some flaring occurred each month with more substantial
events in April and August (Appendix 5). A few hours of smoky flaring occurred
during September 2009 when an unplanned plant shutdown arising from a cable fault
coincided with a fault in the instrument that controlled the air supply to one boiler
which resulted in a problem supplying steam to the flare. Where possible, flaring is
carried out using the ground level flares in preference to the elevated flare with the
aim of reducing the noise and light impacts for local residents. The increased flaring
by Shell in 2009 was primarily due to a number of planned plant shutdowns required
to undertake maintenance; and to a lesser extent due to two unplanned flaring
incidents early in the year.
v)
ExxonMobil and Shell jointly commissioned modelling studies to assess the impact of
emissions from flaring episodes at the Mossmorran Fractionation Plant and the Fife
Ethylene Plant in order to characterise the environmental impact and ensure that
Best Available Techniques are being employed to minimise impacts (Appendix 6).
The assessments considered carbon monoxide (CO), oxides of nitrogen (NOx as
NO2), PM10, PM2.5, sulphur dioxide and volatile organic compounds (VOCs) including
benzene, 1,3-butadiene, butane, hexane, styrene and toluene. Impacts were
modelled for a theoretical worst-case scenario resulting in the simultaneous flaring of
the highest quantities of gas at both sites. Impacts were also modelled for three
potential scenarios involving flaring at the Ethylene plant and these were:
Base load flaring – routine flaring due to normal operation of the plant;
Planned flaring – flaring during a planned shut down of the installation; and
Unplanned flaring – flaring arising from a process problem, leading to the
propane compressor or gas turbine tripping.
The results of the modelling studies indicate that both peak and long term predicted
environmental pollutant concentrations arising as a result of planned or unplanned
flaring activities at the Mossmorran Plants, are well within relevant air quality
standards and assessment levels. The contribution of flare emissions to the total
pollutant concentrations around the Mossmorran plants is small relative to
background levels of air pollution arising from other sources, such as road traffic.
These predictions are consistent with the results of air pollution monitoring
undertaken around the Mossmorran complex before, during and after a period of
planned maintenance and related flaring activity in 2008.
vi)
Fife Council’s Air Quality Updating and Screening Assessment report for 2009
indicates that national air quality objectives are expected to be met in the area
around Mossmorran and Braefoot Bay for all pollutants included in the Air Quality
Standards (Scotland) Regulations 2007.
vii)
Following the recent grant of planning permission for the installation of a wind farm at
Little Raith Farm, north of Auchtertool and near the Mossmorran site perimeter, the
Group has considered the possible impact of the wind turbines on pollutant
dispersion during flaring episodes at Mossmorran. The group specifically considered
a study published by researchers at the University of Glasgow on the interaction of a
flue with wind turbines1. The situation at Mossmorran, however, differs significantly
from the model used in the published study in terms of buoyancy of the plume,
distance between the flare and the wind turbine and number of turbines at Little
Raith. The Group noted that Fife Council would continue to receive air quality
monitoring information from the wind farm at Little Raith as part of the planning
permission and that SEPA would provide an update on any further research and the
position at Little Raith during 2010.
3.
CONCLUSIONS
i)
Emissions from regulated sources within the plants in 2009 remained well within the
limit values set by SEPA for the protection of public health and the environment.
ii)
These results are consistent with the previous work of the Review Group. In the
areas around Mossmorran and Braefoot Bay the 2010 air quality objective for
benzene is being satisfied readily.
iii)
The quantities flared at Mossmorran were lower during 2009 than in any of the three
preceding years, despite an increase in the quanitities flared by Shell. The results of
air quality modelling studies undertaken to assess the impacts of flaring for a range
of worst-case scenarios indicated flaring has a negligible impact on local air quality.
vi)
The Review Group will continue to review the potential for interaction between the
proposed wind turbines at Little Raith and the dispersion of emissions during flaring.
v)
The work undertaken in 2009 demonstrates that emissions from Mossmorran and
Braefoot Bay continue to pose no significant risk to the health of members of the
local community.
1
Fletcher TM, Brown RE (2010) Interaction of an Eulerian flue gas plume with wind turbines.
American Institute of Aeronatics and Astronautics 48th Meeting 4-7th January 2010
APPENDIX 1
The Review Group: Constitution and Terms of Reference
The Review Group reports to Fife Council which requires its operating costs to be financed by
ExxonMobil Chemical Limited (ExxonMobil) and Shell UK Limited (Shell). Review Group members
are appointed by Fife Council.
Professor Sibbett continues as Independent Chair, with representatives from Fife Council, SEPA and
the Institute of Occupational Medicine participating as members. The Review Group also includes
representation in public health from the Dunfermline and West Fife Community Health Partnership
(formerly West Fife Local Health Care Co-operative) on behalf of NHS Fife and two members
represent the local Community Councils. This is designed to ensure that timely and informative
communications can be provided in respect of any relevant health issues that might arise in the local
communities. Representatives of ExxonMobil and Shell attend the Review Group meetings by
invitation.
The full constitution and terms of reference of this reconstituted group are given below. Briefly, the
Review Group’s approach to carrying out its functions has been re-assessed, allowing it to take less
involvement in the monitoring of air quality, but instead to focus attention on the review of such data.
Of particular relevance are issues relating to any health concerns raised by residents within the local
communities and a key role is assisting with the communication of information relating to
environmental air quality.
Detailed Constitution and Terms of Reference
1.0
TITLE
1.1
The Group is known as the Mossmorran & Braefoot Bay Independent Air Quality Monitoring
Review Group (referred to below as the Review Group).
2.0
INTRODUCTION
2.1
The Review Group was formed to provide advice and recommendations to Fife Council
(formerly Fife Regional Council and Dunfermline and Kirkcaldy District Councils) regarding
the monitoring of air emissions arising from the operations at the Mossmorran plants and the
Braefoot Bay terminal facilities. Specific terms of reference which previously pertained were
as required by planning conditions applying to the operation of the plants.
2.2
The Review Group’s approach to carrying out its functions has been re-assessed, allowing it
to take less involvement in the monitoring of air quality, with its primary responsibilities being
re-directed towards reviewing such data. Of particular relevance are issues relating to any
health concerns raised by residents within the local communities, and a key role is assisting
with communications of air quality related information.
3.0
TERMS OF REFERENCE
3.1
The Review Group (as reconstituted in terms of para. 2.2 above) has the following remit:
(i)
To provide advice on air quality related monitoring arrangements.
(ii)
To review air quality monitoring data obtained at sites in the vicinity of the
Mossmorran complex and the Braefoot Bay terminal.
(iii)
To consider, advise and make recommendations on the outcome of monitoring data.
The Review Group intends by inclusion in its membership of public health
representation that timely and informative communications can be provided in respect
of any relevant health issues that might arise in the local communities.
(iv)
To submit reports to Fife Council and to make presentations as appropriate to
representatives of the Community Councils that are local to the Mossmorran plants
and the Braefoot Bay terminal. The Review Group intends inclusion in its
membership of representation from the local Community Councils to assist with this
communications related responsibility.
3.2
These terms of reference shall not imply any responsibility for, control over, or restriction of
the statutory or common law positions of Fife Council, Shell UK Limited (Shell), ExxonMobil
Chemical Limited (ExxonMobil), or any other local authority, statutory authority or agency, or
company, or institution, nor derogate from the rights, powers and responsibilities of such
authorities, agencies, companies or institutions.
4.0
APPROACH
4.1
The Review Group’s approach will be based on:
(i)
Making the Minutes of its meetings publicly available;
(ii)
Ensuring that all reports produced by, or on behalf of, the Review Group are fully
documented and contain source references to all relevant data;
(iii)
Providing regular and non-technical summaries on its activities;
(iv)
Informing the local communities through submissions to existing liaison structures
(i.e. primarily the Mossmorran & Braefoot Bay Community & Safety Committee) and
through direct presentations by Review Group members as appropriate, and
(v)
Being open to approaches from local communities and individuals.
5.0
MEMBERSHIP
5.1
Membership of the Review Group comprises appropriate representation from the following:






An Independent Chair
Fife Council officials
Institute of Occupational Medicine (IOM)
Scottish Environment Protection Agency (SEPA)
Public health services
Community Councils on the Mossmorran & Braefoot Bay Community & Safety
Committee (inland and coastal)
5.2
The Review Group will invite representatives of Shell and ExxonMobil to attend meetings, and
may invite others to address group members on issues related to the terms of reference set
out at para. 3.1 above.
5.3
The Review Group Secretary (see para. 6.2 below) shall maintain a current register of
members, for distribution and information purposes.
5.4
ExxonMobil and Shell maintain a list of Community Council contacts who are notified of
flaring.
6.0
OFFICE BEARERS
6.1
The Independent Chair may be nominated by any member of the Review Group. If any
change in the appointment as Chair is proposed, the agreement of Fife Council will be
required.
6.2
The Review Group approves the appointment of a Secretary, who prepares a record of
meetings and is responsible, in consultation with the Chair, for preparing agenda papers,
summoning the meetings, and circulating a record of meetings to the membership.
6.3
The finalisation of reports by the Review Group shall be as determined by the Chair.
7.0
MEETINGS
7.1
The Review Group will meet as frequently as is considered necessary by the Chair (normally
at least once a year), having regard to the remit set out at para. 3.1 above.
7.2
The Secretary shall send to all members and others, as appropriate, a record of the previous
meeting, together with notice and agenda papers for all meetings of the Review Group, at
least seven days before the day of the meeting.
7.3
Business shall be in keeping with the terms of reference set out at para. 3.1 above.
8.0
FINANCE
8.1
The companies, having met the cost of monitoring work previously undertaken in fulfilment of
planning conditions, shall meet relevant costs based on the advice of the Review Group.
8.2
The local authority shall meet any reasonable costs of the administration of the Review
Group.
APPENDIX 2
Membership of the Review Group (as at December 2009)
Name
Designation/
Representing
Address
Prof. Wilson Sibbett
Independent Chair
School of Physics & Astronomy,
University of St Andrews
Stuart Wilson
Interim Team Leader
(Development, Promotion and
design) Fife Council
Development Services,
Dunfermline
Douglas Mayne
Fife Council (Environmental
Services)
Environmental Services,
Glenrothes
Liz Box
Committee Administrator, Fife
Council
Democratic Services,
Dr Alison Searl
Institute of Occupational Medicine
(IOM)
Edinburgh
Michelle Hickson
Scottish Environment Protection
Agency (SEPA)
Perth
Belinda Morgan
Dunfermline & West Fife
Community Health Partnership
Lynebank Hospital, Dunfermline
Robert Arnott
Crossgates & Mossgreen
Community Council
Crossgates (Inland)
William Dryburgh
Aberdour Community Council
Aberdour (Coastal)
Barry Jarvis
Shell UK Limited
Fife NGL Plant, Mossmorran
Norman White
Shell UK Limited
Fife NGL Plant, Mossmorran
Alex Baird
Shell UK Limited
Fife NGL Plant, Mossmorran
Ian Hackers
ExxonMobil Chemical Limited
Fife Ethylene Plant, Mossmorran
William Sweenie
ExxonMobil Chemical Limited
Fife Ethylene Plant, Mossmorran
Kenny Bisset
Fife Council (Environmental
Services)
Environmental Services,
Glenrothes
Dr. Alastair
Robertson
Institute of Occupational Medicine
Edinburgh
John Lamb
Air Quality Management
Specialist, SEPA
Edinburgh
Dr Jackie Hyland
NHS Fife, Cameron Hospital
Leven, Fife
Linda Whetren
NHS Fife
A. MEMBERS
B. BY INVITATION
George Tickersgill
Auchtertool Community Council
Auchtertool
Alexander
Macdonald
Burntisland Community Council
Burntisland
David Taylor
Cardenden & Kinglassie
Community Council
Cardenden
Alex Haddow
Cowdenbeath Community
Council
Cowdenbeath
Colin McPhail
Dalgety Bay & Hillend Community
Council
Dalgety Bay
Ernest McPherson
Lochgelly Community Council
Lochgelly
APPENDIX 3
Regulatory and Policy changes relating to air quality in 2009
There were no changes in regulation relating to air quality in Scotland during 2009. The
technical guidance for local authorities on how to undertake assessments to meet their
obligations with respect to Local Air Quality Management under the Environment Act, Part IV
(1995) that is provided by DEFRA and the Devolved Administrations was revised during
2008 and published in 2009 as TG(09). There are no implications arising from the revised
guidance for the operations at Mossmorran and Braefoot Bay which are regulated by the
Scottish Environment Protection Agency (SEPA).
Some minor regulatory changes are likely to occur during 2010. A new air quality directive
came into force in June 2008 which must be transposed into national legislation by June
2010 (Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008
on ambient air quality and cleaner air for Europe). This Directive consolidates existing air
quality legislation and provides a new regulatory framework for PM2.5. PM2.5 is the fraction of
PM10 that comprises particles that are less than about 2.5 um in size that are able to
penetrate to the gas exchange region of the lung in people with compromised breathing
(“high risk respirable fraction”). In terms of future air quality regulation in Scotland, the key
feature of the latest Directive are the new objectives and standards for PM2.5 that have
already been adopted as non statutory objectives in Scotland. As with previous EU Air
Quality directives, Scotland has committed to meeting a more demanding target than
required by the Directive (Table).
Table: New objectives for PM2.5
Applies to
Objective
All UK authorities
25 µg m-3 (target)
Annual mean
15% cut in urban Annual mean
background
exposure
12 µg m-3 (limit)
Annual mean
Authorities in
Scotland Only
Averaging time
Date to be
achieved
2020
2010 - 2020
2010
The practical implications of the proposed Scottish objective for PM2.5 include the likelihood
of more stringent measures being imposed by local authorities in order to meet the objective
along heavily trafficked streets. Strict limits on particle emissions are already imposed on
large combustion plant, but some additional measures may be required to limit emissions
from smaller plant such as proposed biomass boilers in public buildings. There are no
foreseeable implications for the operations at the Mossmorran or Braefoot Bay facilities.
The National Emission Ceilings Directive (NECD; Directive 2001/81/EC) set ceilings for the
emissions of four key pollutants to be met by 2010:

Sulphur Dioxide (SO2);

Oxides of Nitrogen (NOx);

Volatile Organic Compounds (VOCs);

Ammonia (NH3);
The NECD is currently being reviewed to produce new emissions ceilings targets for 2020.
The revised targets are due to be delivered during 2010 and may have longer term
implications for the emissions limits set for the operations at the Mossmorran and Braefoot
Bay plants.
APPENDIX 4
Regulated emissions to air

Emissions from all regulated sources at Mossmorran and Braefoot Bay
during 2009 were well within the limits set by SEPA.
SEPA authorises the operations carried out by both Shell and ExxonMobil at Mossmorran
under the Pollution Prevention and Control (Scotland) Regulations 2000 (PPC). The PPC
permits are based on the concept of Integrated Pollution Prevention and Control (IPPC) and
define limits for emissions from the facilities at Mossmorran to air, water and land. SEPA has
set permit conditions that ensure that Best Available Techniques are being employed by the
companies to prevent or generally reduce the impact of emissions on the environment.
ExxonMobil’s ethylene bulk storage at Braefoot Bay is also authorised under the PPC
Regulations for emissions to air only and their vapour control unit, also at Braefoot Bay is
authorised under the Environmental Protection Act 1990.
For airborne emissions from Mossmorran, the Shell and ExxonMobil permits concentrate on
stacks from furnaces, boilers and a gas turbine. They define emission limits for each
regulated source and set out sampling and reporting regimes for assessing compliance with
these limits. The companies must report results to SEPA’s Strathearn Office in Perth for
appraisal. SEPA also make these results available in a public register.
The emissions monitoring measurements for 2009 submitted to SEPA are summarised for
each regulated Shell and ExxonMobil source at Mossmorran in Tables A4.1 to A4.3
respectively, and for Braefoot Bay in Table A4.4. The emission limits, authorised by SEPA
for each emission source, are also listed in these tables. During 2009, emissions from all
regulated sources at Mossmorran were well within the limits set by SEPA.
Table A4.1: Emissions from Regulated Shell Sources at Mossmorran during 2009
CO Concentration (mg/m3)
NOx Concentration
(mg/m3)
SO2 Concentration
(mg/m3)
Authorised
Emissions
Limit
2009
average
Authorised
Emissions
Limit
2009
average
Authorised
Emissions
Limit
2009
average
Furnace 1
100
<6
150
80
10
<10
Furnace 2
100
<6
150
90.3
10
<10
Furnace 3
100
<6
150
86.4
10
<10
Table A4.2: Emissions from Regulated ExxonMobil Sources at Mossmorran during
2009 – sources not included in Large Combustion Plant Directive
CO Concentration
(mg/m3)
Authorised
PPC
Emissions
Limit
no limit
no limit
no limit
no limit
no limit
no limit
no limit
NOx Concentration
(mg/m3)
Authorised
PPC
Emissions
350
350
350
350
350
350
350
2009
Average
nm
nm
nm
nm
nm
nm
nm
Furnace 1
Furnace 2
Furnace 3
Furnace 4
Furnace 5
Furnace 6
Furnace 7
Gas Turbine
Stack
no limit
nm
No limit: no emission limit applied by SEPA
nm: not measured
SO2 Concentration
(mg/m3)
2009
Average
159.7
189.3
172.6
177.8
165.2
193.5
157.7
Authorised
PPC
Emissions
Limit
no limit
no limit
no limit
no limit
no limit
no limit
no limit
316.0
no limit
550
2009
Average
nm
nm
nm
nm
nm
nm
nm
nm
Table A4.3: Emissions from Regulated ExxonMobil Sources at Mossmorran during
2009 – sources included in Large Combustion Plant Directive
CO Concentration
(mg/m3)
Authorised PPC
Emissions Limit
2009
Average
Boiler A
200
0.3
Boiler B
200
1.4
Boiler C
200
0.2
NOx Concentration
(mg/m3)
Authorised
PPC/LCPD
Emissions Limit
Limit
is
fuel
weighted (450 on
liquid fuel, 350 on
gas).
Limit
is
fuel
weighted (450 on
liquid fuel, 350 on
gas).
Limit
is
fuel
weighted (450 on
liquid fuel, 350 on
gas).
2009
Average
94.8
104.1
119.1
SO2 Concentration
(mg/m3)
Authorised
PPC/LCPD
Emissions Limit
Limit
is
fuel
weighted (1,700 on
liquid fuel, 35 on
gas).
Limit
is
fuel
weighted (1,700 on
liquid fuel, 35 on
gas).
Limit
is
fuel
weighted (1,700 on
liquid fuel, 35 on
gas).
2009
Average
28.2
143.7
0.3
LCPD = Large Combustion Plant Directive
Table A4.4: Emissions of Benzene and Total Hydrocarbon from ExxonMobil Regulated
Source at Braefoot Bay (Vapour Control Unit) measured in 2009
Activities during
monitoring period
Benzene (mg/m3)
VOCs (mgm-3)
(Authorised Limit = 10
mg/m3)
(Authorised Limit = 20
mg/m3)
26 March 2009
<0.17
<0.1
road tanker offloading
03 June 2009
<1.21
2.5
C5+ ship loading
30 June 2009
<1.84
1.0
road tanker offloading
28 September 2009
<1.83
3.3
road tanker offloading
02 November 2009
<1.83
2.6
road tanker offloading
13 November 2009
<0.62
1.4
C5+ ship loading
Date
APPENDIX 5
2009 Flaring Report
A5.2
ExxonMobil Fife Ethylene Plant
2009 Flaring Report
A5.2
ExxonMobil Fife Ethylene Plant
Table A5.1, below, indicates the quantities flared during 2009. There were a small number of
periods of planned and unplanned maintenance that led to plant shutdown and flaring during
the year. There was a short period of smoking flaring over a few hours in September 2009
following a cable fault on an instrument that led to an unplanned plant shutdown and flaring.
The shutdown coincided with a fault on another instrument controlling the air intake to B
boiler that resulted in a low steam header pressure, reduced steam supply to the flare and a
smoky flare. Measures were quickly put in place to improve flare combustion and the smoky
episode was short lived. Both ExxonMobil and SEPA have reviewed the circumstances
leading to the episode with a view to identifying the cause of the problem and putting
measures in place to prevent a reoccurrence. The boiler instrument that failed was less than
1 year old and a review has been undertaken with the manufacturers in order to fix this
instrument and the other two boilers.
Table A5.1 Quantities Flared from the ExxonMobil Fife Ethylene Plant
Month
Flaring from
Planned Start
Up/Shutdown
Flaring
Elevated
Flare
Tonnes
Flared
January
February
March
April
May
0
2
0
0
Ground
Flares
Tonnes
Flared
0
0
0
0
Flaring from
Routine, Normal
Baseline
Operations
Elevated
Flare
Tonnes
Flared
0
2
64
22
Ground
Flares
Tonnes
Flared
227
281
211
271
Flaring from
Abnormal or Non
Routine
Operations
Elevated
Flare
Tonnes
Flared
0
2
0
0
Ground
Flares
Tonnes
Flared
0
0
0
0
0
0
26
294
529
440
1220
152
7
257
0
0
0
0
0
0
0
0
26
99
0
306
152
229
0
0
3431
0
0
887
0
0
0
0
0
0
30
9
9
269
231
192
0
0
0
0
0
0
June
July
August
September
October
November
December
Event Reason
Elevated
flaring
due to Acetylene
Convertors outwith
specification
Sulfinol
Plant
shutdown to carry
out line repairs.
1.
Demethaniser
trip
2. C-P-503
CV
positioner
repair
The quantity flared varies from year to year depending on circumstances. The ground level
flares are used in preference to the high level flare because the operators seek to minimise
noise and light nuisance for local residents. The quantity flared in 2009 was substantially
less than in each of the preceding three years as shown in the bar chart below.
Tonnes flared: elevated and ground flares
40000
35000
30000
25000
20000
15000
10000
5000
0
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Year
A5.2
Shell Natural Gas Liquefaction Plant
The total quantity flared in 2009 was 1836 tonnes compared with 392.3 tonnes in 2008. The
increased flaring in 2009 was primarily due to a number of planned plant shutdowns required
to undertake maintenance; and to a lesser extent due to two unplanned flaring incidents
early in the year. The quantities flared each month are summarised in the bar chart below.
Tonnes flared
2000
1500
1000
500
0
2005
2006
2007
Years
2008
2009
APPENDIX 6
Local air quality modelling studies for the Fife Ethylene Plant and
Mossmorran Fractionation Plant
Non Technical summary
______________________________________________________________
Introduction
1) ExxonMobil and Shell jointly commissioned the independent consultants Entec to
undertake comprehensive modelling studies to assess the impact of emissions from
flaring episodes at the Mossmorran Fractionation Plant and the Fife Ethylene Plant
(FEP) in order to meet conditions within the environmental permits for the two plants.
Both plants were required to assess the impact of emissions from flaring episodes in
order to characterise the environmental impact and ensure that Best Available
Techniques are being employed to minimise impacts.
2) Dispersion modelling is a tool that enables the assessment of the air pollution impacts of
events such as flaring. The impacts of flaring events are difficult to assess through air
quality monitoring because they are typically unplanned. Modelling is particularly
important in the estimation of worst case effects as even planned intervals of flaring are
unlikely to coincide with the weather conditions that would give rise to the highest
potential pollutant concentrations. Modelling also allows the prediction of impacts at any
location within the area included for study, whereas cost and practicality limit monitoring
to a few discrete locations within the area of interest.
3) The assessments considered carbon monoxide (CO), oxides of nitrogen (NOx as NO 2),
PM10, PM2.5, sulphur dioxide and volatile organic compounds (VOCs) including benzene,
1,3-butadiene, butane, hexane, styrene and toluene.
4) The assessments included both short term and long term air quality impacts. Predicted
impacts were compared against the Scottish Government’s air quality objectives for CO,
NO2, PM10, PM2.5, 1,3-butadiene and benzene and the Environment Agency’s
Environmental Assessment Levels for the remaining pollutants. These standards and
assessment levels are set for the protection of human health.
5) Background pollutant concentrations are up to 40% of the relevant objectives or
assessment levels (depending on pollutant) for short term peak events (15 minutes, 1
hour or 24 hours) and up to 57% of the relevant objectives or assessment levels for
annual mean concentrations.
Simultaneous flaring at both plants
6) Impacts were modelled for a theoretical worst-case scenario resulting in the
simultaneous flaring of the highest quantities of gas at both sites. This could arise if
planned flaring on the Shell site arising from the shut down of a single module was
combined with a simultaneous gas turbine failure at the FEP.
7) The maximum predicted short term peak environmental concentrations of the study
pollutants as assessed from the sum of the maximum predicted increment and
background concentration for each pollutant in ambient air were all less that 48% of the
relevant air quality objective or environmental assessment level. The predicted
increments in pollutant concentrations arising from flaring were less than 15% of the
short term objective for NO2, less than 10% of the short term objective for PM10 and less
than 5% of the short term environmental assessment level for benzene. The predicted
increments of other pollutants were much smaller in relation to relevant objectives and
assessment levels. The predicted increments in pollutant concentrations arising from
flaring were smaller than background concentrations of pollutants.
8) The predicted impacts of flaring on annual mean concentrations of air pollutants were
assessed by considering the likely frequency and duration of flaring episodes during the
year. The predicted increments in pollutant concentrations arising from flaring were less
than 10% of the annual mean objectives for NO2 and benzene and less than 4% of the
annual mean objectives for PM10 and PM2.5. The predicted increments of other pollutants
were much smaller in relation to relevant objectives and assessment levels. The
predicted annual mean concentrations (background plus increment) were less than 59%
of the relevant air quality objective or assessment level.
Flaring at the Fife Ethylene Plant
9) The study considered the following three potential scenarios:
Base load flaring – routine flaring due to normal operation of the plant;
Planned flaring – flaring during a planned shut down of the installation: and
Unplanned flaring – flaring arising from a process problem, leading to the propane
compressor or gas turbine tripping.
10) The modelling took account of variations in emissions from other point sources on site
arising during flaring episodes.
11) The maximum predicted short term peak environmental concentrations of the study
pollutants were all less that 48% of the relevant National Air Quality Standard or
Environmental Assessment Level. The predicted increments in pollutant concentrations
arising from flaring were up to about 15% of the short term objective for NO2 and less
than 5% of the short term objectives/assessment levels for PM10 and benzene. The
predicted increments of other pollutants were much smaller in relation to relevant
objectives and assessment levels. The predicted increments in pollutant concentrations
arising from flaring were smaller than the background concentrations of pollutants.
12) The predicted impacts of flaring on annual mean concentrations of air pollutants were
assessed by considering the likely frequency and duration of flaring episodes during the
year. The predicted increments in pollutant concentrations arising from flaring were less
than 10% of the annual mean objectives for NO2 and benzene and less than 5% of the
annual mean objectives for PM10 and PM2.5. The predicted increments of other pollutants
were much smaller in relation to relevant objectives and assessment levels. The
predicted annual mean concentrations (background plus increment) were less than 59%
of the relevant air quality objective or assessment level.
13) The output from the modelling study are consistent with the results of air pollution
monitoring undertaken around the Mossmorran complex before, during and after a
period of planned maintenance and related flaring activity between 21 August and 1
October 2008 and reviewed in the 2008 Annual Report.
14) The predicted short term impacts on concentrations of NO2, CO and PM10 during
unplanned flaring at the Fife Ethylene Plant were greater than those predicted for
combined flaring at both sites. This is because part of the FEP gas stream would be sent
to the Shell ground flares if there is a turbine trip at the FEP while the Fractionation Plant
is operating normally. The Shell Ground Flares have a lower effective release height that
the FEP elevated flare and therefore have poorer dispersion characteristics resulting in
higher ground level concentrations. The visual and noise impacts of the ground level
flares are, however, much smaller than those of the high level flare and it is considered
appropriate to send part of the gas stream to the ground level flares in order to minimise
these impacts.
Conclusion
5) The results of the modelling studies indicate that both peak and long term predicted
environmental pollutant concentrations arising as a result of planned or unplanned
flaring activities at the Mossmorran Plants, are well within relevant air quality
standards and assessment levels. The contribution of flare emissions to the total
pollutant concentrations around the Mossmorran plants is small relative to
background levels of air pollution arising from other sources, such as road traffic.
These predictions are consistent with the results of air pollution monitoring
undertaken around the Mossmorran complex before, during and after a period of
planned maintenance and related flaring activity in 2008.
APPENDIX 7
GLOSSARY
Concentration Units
ppb: parts per billion by volume, concentration unit for gases and vapours, equivalent to one
cubic millimetre of gas mixed with one cubic metre of air.
ppm: parts per million by volume, concentration unit for gases and vapours, equivalent to
one cubic centimetre of gas
µg/m3: microgram per cubic metre, mass concentration unit for particulates and gases.
There are 1,000,000 micrograms in a gram and 25,000,000 micrograms in an ounce.
mg/m3: milligram per cubic metre, mass concentration unit for particulates and gases. 1
mg/m3 = 1,000 g/m3.
Pollutants
PM10: This is the fine fraction of airborne dust, defined by international convention, that can
be deposited in the lung. It is the fraction of airborne dust around which the UK air quality
standard is defined. There are many sources, including road traffic, agriculture, industry and
many personal activities. It includes particles that are approximately less than 10 μm in
diameter.
PM2.5: This is a subfraction of PM10 sometimes referred to as “high risk respirable”. It is the
fraction of airborne particles that can penetrate to the gas exchange region of the lungs in
those with compromised respiratory health. PM2.5 is largely comprised of particles generated
by combustion plus particles that form as a result of reactions in the atmosphere. These
include particles that form from sulphur dioxide and nitrogen oxides.
Benzene: This aromatic hydrocarbon is a minor component of petrol. Fuel distribution and
car exhausts are its most important environmental source. It is present in cigarette smoke,
some foods and drinks and widely in nature. Benzene is recognised as causing cancer in
people.
1,3-Butadiene: Butadiene is a hydrocarbon that arises in air solely from human activity. It is
an important industrial chemical, being used in synthetic rubber manufacture and is found in
some liquid petroleum gases. Its main sources in the environment are, however, from road
traffic emissions. It is considered as capable of causing cancer in people.
Nitrogen Dioxide: This gas is produced by the reaction of oxygen and nitrogen during
combustion. Vehicle emissions are a major source. It is well known as an irritant and, more
recently, has been found to affect health at concentrations that can be found in the
environment and indoors. Nitric oxide always occurs when nitrogen dioxide is formed. The
two gases together are known as oxides of nitrogen, sometimes described in shorthand form
as NOx..
VOCs or Volatile Organic Compounds: Carbon-based (or organic) chemicals that readily
evaporate. Many hydrocarbons, including benzene, butane, pentane and hexane are VOCs.
Organisations/facilities
SEPA: Scottish Environment Protection Agency
FEP: Fife Ethylene Plant - ExxonMobil Chemical Limited (ExxonMobil)’s production facility at
Mossmorran
Fife NGL Plant: Fife Natural Gas Liquids Plant – comprises Shell UK Limited (Shell)’s
production facility at Mossmorran for the fractionation of liquefied natural gas
NPL: National Physical Laboratory
Other
ELV: Emission Limit Value
PPC: Pollution Prevention and Control