Atmospheric Emissions – Power Generation


This Topic now focuses on requirements under the Offshore Combustion Installations (Prevention and Control of Pollution) Regulations 2001 and Merchant Shipping Regulations. UK ETS requirements are now covered under a standalone topic (see UK ETS).

For information on the impact of Brexit on oil and gas environmental legislation, please refer to the pdf document downloadable from the Home Page.

Key Legislation:

For more detail on the Legislation relevant to this page, please use the following links:

Supporting Legislation/Other Trading Schemes:


Guidance Notes:

General Guidance

Consent Needed: PPC Regulations  No offshore combustion installation* can be operated except in accordance with a permit issued under the PPC Regulations. A permit is required for any combustion installation (gas turbines, diesels, direct drive compressors, heaters, etc.) located on an offshore oil or gas platform, or other producing facility, where an item of combustion plant on its own, or together with any other combustion plant installed on a platform, has a rated thermal input exceeding 50 MW (th). This 50 MW (th) threshold applies to all operational combustion equipment.*‘Combustion Installation’ refers to the total combustion plant on a platform or group of co-located platforms and is distinct from the offshore installation itself. There are a number of exclusions including for example shuttle tankers and mobile drilling rigs. A ‘substantial change’ means ‘in relation to combustion installations, a change in operation which may have significant negative effects on human beings or the environment’. (See Renewal and Variation Tab for details on the process of determining substantial change).MARPOL Annex VIA UK Air Pollution Certificate (UKAPP) or International Air Pollution Certificate (IAPP).EU Emissions Trading SchemeSee EU ETS Topic.
How to Apply:

PPC Regulations  Permit application shall be in writing and shall contain a description of the following:

  • A description of the installation, its activities and its location
  • The materials, substances and energy used in or generated by the installation
  • The sources of emissions (release routes) from the installation
  • The nature and quantities of foreseeable emissions from the installation into each medium as well as identification of significant effects of the emissions on the environment
  • The proposed technology and other techniques for preventing or, where this is not possible, reducing emissions from the installation
  • Where necessary, measures for the prevention and recovery of waste generated by the installation
  • Measures planned to monitor emissions into the environment.

Information on new combustion installation(s) in new developments may be included in an Environmental Statement (ES), or otherwise attached to it by a reference in the main ES document. An application for a permit has to be made separately but a copy of the ES then need only accompany it with the covering letter indicating where the required information can be found.

The permit is based on a mass emissions approach for each of the main pollutants. As oil/gas production declines over field life, emissions will not be constant. It is envisaged that during the study phase, the operator will prepare yearly predictions of each emissions and these will form the basis for negotiation of the overall permit mass emissions (tonnes) for each pollutant. A pro forma of a typical permit application is given in Annex 1 to the Department for Energy Security and Net Zero (then DECC) Guidance Notes (PDF document).


MODU or others registered as a ship will be inspected by the MCA.

Fixed installations will be insepcted by the Department for Energy Security and Net Zero.

EU Emissions Trading Scheme

See EU ETS Topic.

Who to Apply to: PPC Permit  All applications for a permit should be sent to the Environmental Management Team at: the Department for Energy Security and Net ZeroEDU Licensing and Consent Unit (LCU-OED)
Atholl House
86/88 Guild Street
AB11 6ARMARPOL Annex VISee aboveEU Emissions Trading SchemeSee EU ETS Topic.
When to Apply: PPC Permit  Any new installation or existing installation undergoing a substantial change will need a permit in place before operations or modifications commence. Applications should be submitted 6 months before start up of the new combustion plant.MARPOL Annex VI For new rigs/installations – survey and certification before first sail out.For existing rigs/installations – inspections and certification will be undertaken at time of next inspection.EU Emissions Trading SchemeSee EU ETS Topic.
Exclusions/Exemptions to MARPOL Annex VI:

Annex VI only applies to diesel engines over 130 KW and does not apply to turbines. Emissions arising directly from the exploration, exploitation and associated offshore processing of seabed mineral resources are exempt from Annex VI, including the following:

  • Emissions resulting from flaring, burning of cuttings, muds, well clean-up Emissions and well testing.
  • Release of gases entrained in drilling fluids and cuttings.
  • Emissions from treatment, handling and storage of reservoir hydrocarbons.
  • Emissions from diesel engines solely dedicated to the exploitation of seabed mineral resources.

In addition, Regulation 13 concerning NOx does not apply to emergency diesel engines, engines installed in lifeboats or equipment intended to be used solely in case of emergency.

PPC Permit Conditions:

Any PPC Permit granted by the Secretary of State will have conditions relating to the following (amongst others) in place:

  • Required pollution prevention measures in particular through the application of Best Available Technology (BAT)
  • Requirement that the production of non-gaseous waste is avoided where possible by using clean technologies or using waste minimisation/waste recovery technologies
  • Energy is used efficiently
  • Necessary measures are taken to prevent accidents and limit their consequences in relation to the environment
  • Necessary measures are taken to ensure any liquid or solid wastes are recovered for onshore recycling or disposal or offshore disposal in accordance with any other relevant legislation
  • Necessary measures are taken upon cessation of activities to avoid any pollution risk and to decommission and remove the combustion installation
  • Emission controls are in place in the form of emission value limits or equivalent parameters or technical measures or a combination of the two
  • Monitoring and measurement requirements to enable verification of compliance with the permit
  • Provisions on the minimisation of long-distance and transboundary pollution
  • Measures relating to conditions other than normal operating conditions, e.g. process upsets and start-ups

If the application includes a plan to reduce pollution from the combustion installation, then the Secretary of State may allow the condition to achieve energy efficiency to lapse but only for six months starting with the date the permit is issued.

The Department for Energy Security and Net Zero’s preferred approach is to consider the direct mass emissions of combustion pollutants from the entire platform or floater, rather than emissions quantified in terms of mass emissions per unit volume of exhaust gas from each item of combustion plant. In an offshore context, it is considered that this will enable Operators to devote more resources to emissions from the bigger sources (e.g. main power generation turbines), which dominate the releases offshore.

PPC – Energy Assessments:

The requirement to undertake an energy assessment is a condition of most offshore PPC permits. The energy assessment should incorporate three main elements:

  • Independent review of emissions of Greenhouse Gases (GHG) and other atmospheric pollutants and investigation and quantification of any potential opportunities to reduce emissions
  • Independent review of the energy usage on an asset, and investigation and quantification of any potential opportunities to avoid energy wastage
  • Demonstration to the Department for Energy Security and Net Zero’s satisfaction that the whole plant is being operated in the most energy efficient manner that is financially viable.

Guidance is now available on the methodology for undertaking an energy assessment (see the Guidance section under the Legislation tab)

EU Emissions Trading Scheme: See EU ETS Topic for EU ETS performance standards.
MARPOL Annex VI – Diesel Sampling: Regulation 18 of Annex VI requires that every delivery of diesel be recorded on a bunker delivery note and that a sample of each delivery to be taken and retained for 12 months. However, the MCA has taken a pragmatic approach and will not require the full MARPOL procedure to be applied for the delivery of fuel to an installation. The MCA would like to see a common industry procedure developed and has been in discussion with the Chamber of Shipping on this. Oil & Gas UK is involved in these discussions.Diesel must only be supplied by a registered Fuel Oil Supplier. For the list of registered suppliers see the MCA website.
Marine Fuel Oil Suppliers: MARPOL Annex VI came into force internationally on 18 May 2005. To implement Regulation 18 in the UK, local marine fuel oil suppliers must provide bunker delivery notes to vessels over 400 GRT and be on a UK register of local suppliers.
NOx Emission Limits for Marine Diesel Engines: The MCA has issued a Marine Guidance Note (MGN 142) that establishes NOx emission limits for marine diesel engines with more than 130 kW power output, which are installed in ships, vessels or offshore installations constructed after 1 January 2000. The same limits will also be applied to marine diesel engines with more than 130 kW power output which undergo a major conversion where the maximum continuous rating of an engine is increased by more than 10%.  MGN 142 (PDF Document) also provides guidance for testing, survey and certification and for demonstrating compliance of such engines. These are now known as Tier I limits.Revised Annex VI requirements sets a 20% reduction over current NOx (Tier 1) standards for ships constructed on or after 1 January 2011, and these are to be known as Tier II limits.Ships constructed on or after 1 January 2016 operating on a NOX emission control area, a further 80% reduction will apply (Tier III limits). The more stringent Tier III standards are expected to be met through developing technologies such as water induction into the combustion process, exhaust gas recirculation and selective catalytic reduction. The new three tier approach and specific emission limits are summarised in MIN 395. NOX limits for existing marine diesel engines are also described.
Revised Annex VI – SOX and Particulate Matter Emissions: The current global cap of 4.5% sulphur content will be reduced to 3.5% from 1 January 2012 and further reduced to 0.5% from 1 January 2020 (however, this will be subject to a review on availability of suitable fuel to be completed no later than 2018).With regard to SOX emission control areas the current cap of 1.5% sulphur content has been reduced to 1.00% from 1 July 2010 and 0.1% from 1 January 2015. From 1 January 2008 the sulphur content of marine gas oil must not exceed 0.1%. For further information reference can be made to the Marine Information Notice (MIN 317) – The Sulphur Content of Gas Oil and Marine Gas as per Council Directive 199/32/EC (PDF Document). Note – marine diesel is excluded from this requirement.
Public Participation Directive:

The Public Participation Directive (PPD) requires a number of aspects of public notification and consultation, and the Offshore Combustion Regulations have been amended to incorporate these:

  1. An outline of main alternatives (if any) should be included in permit applications.
  2. The public should be notified and made aware of any decisions making available relevant consents and permits with the reasons and considerations on which decisions have been based.
  3. Public notification must be at the earliest possible time where the information can be provided on the nature of possible decisions.
  4. Making available within time-frames the necessary reports, advice issued to the regulator in accordance with legislation when applications were made and information relevant to a decision which only became available after advertisement of an application.
PPC Permit Monitoring Requirements:

Where possible, direct measurements should be taken for emission reporting or generation of machine specific factors for emission calculations. Although there are inherent inaccuracies in the measurement of emissions in an exhaust stack, it is considered by BEIS to be an acceptable method of determining the emissions from a machine.Pollutant gases and the thermal efficiency of the plant have to be monitored and reported. The main pollutant gases that will need monitoring are:

  1. Oxides of nitrogen and other nitrogen compounds.
  2. Sulphur dioxide and other sulphur compounds.
  3. Carbon monoxide.
  4. Unburned Hydrocarbons – UHC*.

(* In practice, it is expected that only UHC as an overall ‘total hydrocarbons’ will be measured/monitored, rather than each individual hydrocarbon gas, although an indication of the ratio between methane and other hydrocarbon gases should be estimated).  BEIS published The Offshore Combustion Installations (Pollution Prevention and Control) Regulations 2013 – Offshore Emissions Monitoring Guidance in 2016 (PDF document.

In order to establish an emissions baseline, direct measurement of combustion plant exhausts must be carried out. Priority should be given to monitoring of the principal emitters, i.e. the gas turbines. Monitoring of any remaining combustion plant, which has not been included in the first phase, should be conducted thereafter.

Predictive Emissions Monitoring Systems (PEMS) are considered an acceptable means of monitoring emissions from turbine exhausts as well as offering machine management benefits. However, direct measurements must be carried out initially to verify the emissions estimate from the PEMS.

More information on measurement and monitoring requirements can be obtained from Offshore PPC (Combustion Plant) Monitoring Guide (PDF document), in particular information on frequency of measurements required.

The monitoring programme must be agreed with DECC before commencing the programme, and the initial survey must be completed within twelve months of first permit issue or first oil and gas. Monitoring reports must be submitted directly to DECC at within 3 months of completion of each survey or by any other deadline given in the PPC permit. The frequency and scope of ongoing monitoring surveys will be reviewed following an assessment of the results of each survey.

BEIS has revised and updated the Offshore PPC (Combustion Plant) Monitoring Guide (PDF document), to provide clearer guidance to operators on what constitutes ‘Best Practice’ with respect to offshore emissions monitoring. The principle objective was to detail the minimum requirements for valid initial baseline measurements, and to outline how these can be achieved.

EU Emissions Trading Scheme: See the EU ETS Topic for EU ETS monitoring and sampling requirements.
What to Report: PPC Permit  Emissions reporting is required for all relevant installations. Annual reporting will be required thereafter. Wherever possible this data should be gathered from sampling rather than calculated from emissions factors (see the Sampling/Monitoring Requirements tab).  Generic emissions factors such as those produced by Oil & Gas UK will no longer be an acceptable means of estimating emissions for reporting under the Regulations. An approach more tailored to the specific equipment item will be required. In theory, there may be some scope to use vendor emission factor data to predict emissions rather than installing a monitoring port and carrying out machine specific measurements. However due to the limited dataset available, this approach could not be assumed to give good agreement in all cases. Extensive verification is required in order for such a method to meet with the Department for Energy Security and Net Zero approval. Operators should also provide information on pathways of release, methods of relevant monitoring, sampling and analysis which are acceptable to the Department for Energy Security and Net Zero, and provide evidence that quality assurance procedures are in place to ensure all monitoring and test results are sufficiently accurate and reliable. Where the Operator uses a specialist monitoring contractor, then the Operator shall be responsible for ensuring that the appropriate technical skills, equipment, QA procedures, etc. are in place within the contractor’s organisation.EU Emissions Trading Scheme See EU ETS Topic.
How to Report: PPC Permit  Statutory reporting required under the PPC Regime is to be submitted via the EEMS Atmospheric Reporting system. The Atmospherics reporting form can be obtained from the EEMS website.EU Emissions Trading Scheme See EU ETS Topic.
Who to Report to: PPC Permit  Completed EEMS reports are submitted electronically to the EEMS website.EU Emissions Trading SchemeSee EU ETS Topic.
When to Report: PPC Permit  The EEMS report is to be submitted by 7 February each year. The section of the report of relevance to the PPC Permit will be verified by EEMS and then returned to the operator for signature. EEMS will then submit the verified report to the Department for Energy Security and Net Zero by 1 March each year. For more information see the EEMS website.EU Emissions Trading SchemeSee EU ETS Topic.
European Pollutant Release and Transfer Register (E-PRTR) and UK-PRTR: See Atmospheric Emissions Reporting.
PPC Non-Compliance:

Any non-compliance with PPC permit conditions, issued under the Offshore Combustion Installations (Pollution Prevention and Control) Regulations 2013, as amended, should be reported to OPRED through the submission of a PPC NCN on the Integrated Reporting Service (IRS) on the UK Energy Portal. If the IRS system is unavailable, a PPC non-compliance notification form should be sent to OPRED. Examples of non-compliance may include, but are not limited to:

  • Exceeding total annual emissions of polluting substances from combustion equipment authorised under the permit
  • Failure to carry out and/or submit monitoring programme survey and findings, independent energy audits, cost benefit analysis or improvement programmes if requested by the Department.
Offshore Inspection: The Department for Energy Security and Net Zero (then DECC) Offshore Oil and Gas Environment Unit Enforcement Policy (PDF document) sets out the general principles that Inspectors shall follow in relation to enforcement including prosecution.
Enforcement Notice – PPC Permits: This regulation empowers the Secretary of State to issue a notice – known as an ‘enforcement notice’ – where he is of the opinion that an operator has contravened or is contravening any condition of his permit. The Secretary of State will do this by issuing a notice which will state what the contravention is, what measures must be taken to remedy or prevent the contravention and the time scale in which these measures must be taken. Such measures can include the steps to be taken to remedy any pollution caused.
Prohibition Notice – PPC Permits: This regulation empowers the Secretary of State to issue a notice – known as a ‘prohibition notice’ – where he is of the opinion that the operation of combustion plant. Such a notice can cover any aspect of the operation of a combustion installation – not just the conditions in an existing permit. A prohibition notice will state the Secretary of State’s opinion, specify the risk involved, specify the steps to be taken to remove the risk and the timescale in which they must be done, and direct that an existing permit shall be withdrawn wholly or to the extent specified in the notice until the notice is withdrawn. The Secretary of State may withdraw a prohibition notice if he satisfied that the steps specified in it have been taken.
EU ETS: See EU ETS Topic.
PPC Permits – Renewal: The PPC Permit shall be subject to formal review every 5 years. The Department for Energy Security and Net Zero will contact the installation operator at least 3 months prior to review to confirm the arrangements for it. The operator will need to provide to the Department for Energy Security and Net Zero any information that is reasonably necessary to undertake a review. If the results of the review indicate that the atmospheric emissions and/or combustion plant efficiency estimates are at variance with the existing permit, the operator will be required to submit revised estimates to the Department for Energy Security and Net Zero to support an application for a permit variation.
PPC Permits – Evaluation of Substantial Change:

It is suggested that applicants prepare a PPC application detailing before and after emission profiles, and use this, together with an examination for significant environmental impact, as the basis for discussion with the Department for Energy Security and Net Zero. The Department for Energy Security and Net Zero will enter into dialogue with the applicant and will give its decision as to whether the change is considered “substantial”. If substantial change is deemed likely to occur, then the initial study work can be used as input to a formal IPPC application.Any queries regarding ‘Substantial Change Assessment’ should be directed at the appropriate Environmental Manager within the Department for Energy Security and Net Zero Team. The Department for Energy Security and Net Zero EIA Guidance (PDF document) details the following as a guide for evaluating substantial change.

  • If there is an increase between 40,000 – 100,000 tonnes of CO2 at the host installation then this may constitute substantial change under the PPC Regulations. An application to vary the PPC permit will be required.
  • If as a result of the propopsed activity there is an increase of >100,000 tonnes CO2, a new PPC application would be required.
PPC Permits – Variation: If in the course of field production, unforeseen circumstances mean that the original permitted tonnage values of emissions are likely to show a marked increase, then either a variation to the terms and conditions of a permit can be sought, or an application for a revised permit will need to be made. Additionally, The Department for Energy Security and Net Zero should be advised of marked change to the fuel composition or overall fuel mix.
PPC Permits – Operational Down-sizing: It is recognised that space on offshore facilities is at a premium, and that combustion installations may be removed or rendered inoperable when oil/gas throughput has fallen from original plateau levels. If this results in the facility falling to the overall 50 MW(th) level or less, then there will no longer be a requirement for a permit under the Regulations, and the permit should be surrendered in this situation. The Department for Energy Security and Net Zero will require evidence that plant rendered “inoperable” is physically disconnected to ensure it is indeed inoperable.
EU ETS Permit – Variation: See EU ETS Topic.
EU ETS Permit – Closure of Installation: See EU ETS Topic.

Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency, amending Directives 2009/125/EC and 2010/30/EU and repealing Directives 2004/8/EC and 2006/32/EC:

Energy efficiency is a valuable means to address the EU’s increased energy import dependency and scarce energy resources. It improves the EU’s security of supply by reducing primary energy consumption and decreasing energy imports.

Further details are available from the Official Journal of the EU.

Draft Clean Air Strategy 2018 The draft Clean Air Strategy outlines ambitions to reduce overall air pollution and make our air healthier to breath, protect nature and boost the economy.
It highlights the importance of effective co-operation with the devolved administrations and sets out actions already underway in Scotland, Wales and Northern Ireland to cut air pollution right across the UK. It is currently under consultation.
Improving air quality: reducing emissions from medium combustion plants and generators

Summary of responses and government response now available here.

MIN 519 (M+F) MARPOL – Amendments to MARPOL Annex VI – Chapter 3

The purpose of this Note is to inform the industry of the amendments to Chapter 3 in Annex VI of the International Convention on the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978 (MARPOL 73/78).

The amendment is regarding the control of emissions from ships, particularly Nitrogen Oxides (NOx). Non identical replacement marine diesel engines must meet the standards in this regulation although exceptions apply.  The regulations entered into force internationally on 1st September 2015. The note is accessible here.

Updated Energy and Emissions projections: 2015

A report detailing projections of the UK emissions performance against national greenhouse gas targets under existing policies has been released by the Department for Energy Security and Net Zero. It includes projections of the demand for each type of fuel for different sectors of the economy. The report includes projected energy demand for electricity and indicates what mix of generation will meet it (link here).

Transitional National Plan (TNP): quarterly register
The TNP scheme allows large combustion plants (with a thermal rating equal to or greater than 50 megawatts) first licensed before 27 November 2002 to trade their annual allowances for sulphur dioxide, nitrogen oxide and particulate matter (dust) with other large combustion plants within the TNP scheme.