ISO/DIS 6338-4:2026(en)

ISO/TC 67/SC 9

Secretariat: AFNOR

Date: 2025-12-12

Calculations of greenhouse gas (GHG) emissions throughout the liquefied natural gas (LNG) chain —

Part 4:
Shipping

Calcul des émissions de gaz à effet de serre (GES) dans la chaîne gaz naturel liquéfié (GNL) —

Partie 4: Transport maritime

© ISO 2026

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Contents

Foreword iv

Introduction v

1 Scope 1

2 Normative references 1

3 Terms and definitions 1

4 Principles 1

5 GHG inventory boundaries 1

6 Quantification of GHG emissions 2

6.1 Identification of GHG sources and quantification approach 2

6.1.1 General 2

6.1.2 Emissions from combustion 2

6.1.3 Emissions from fuel cells 3

6.1.4 Emissions from venting 3

6.1.5 Fugitive emissions 4

6.1.6 Emissions associated with imported energy, utilities, and consumables 4

6.2 Calculation of GHG emissions 4

6.3 Preferred units 4

6.4 Allocation 4

6.5 Carbon capture 4

7 GHG inventory quality management 4

8 GHG reporting 4

9 Independent review 5

Bibliography 6

Foreword

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This document was prepared by Technical Committee ISO/TC 67, Oil and gas industries including lower carbon energy, Subcommittee SC 9, Production, transport and storage facilities for cryogenic liquefied gases.

A list of all parts in the ISO 6338 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Natural gas will play a key role in the energy transition (e.g. by replacing coal to produce electricity) and the use of liquefied natural gas (LNG) to transport natural gas is expected to increase. The process of liquefying natural gas is energy-intensive. Gas producers are increasingly accountable for their greenhouse gas (GHG) emissions and the ambition to reduce them. Furthermore, there is an emerging marketing demand for GHG data to enable commercial mechanisms such as offsetting to be utilized.

There is no standardized and auditable methodology to calculate the carbon footprint of the whole LNG chain (including but not limited to the well, upstream treatment, transportation, liquefaction, shipping, regasification and end user distribution). Various standards indicate possible approaches but are inconsistent in their results or not easily applicable.

The ISO 6338 series covers each part of the LNG chain and enables a consistent GHG inventory.

The KPIs and related requirements to access to key international initiatives, agreements and reporting/accounting standards on climate ambitions and zero carbon emission strategies are given in ISO 6338-1:2024, Annex B.

Attention should be paid to activities that can occur in different parts (e.g. gas treatment and distribution upstream of the liquefaction plant).

NOTE It is not possible to make like-for-like comparisons, or define a certification scheme, for one block only.

Calculations of greenhouse gas (GHG) emissions throughout the liquefied natural gas (LNG) chain —
Part 4:
Shipping

This document provides the part of the method to calculate the GHG emissions throughout the LNG chain specific to shipping.

The general requirements are covered in ISO 6338-1.

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 6338‑1, Calculations of greenhouse gas (GHG) emissions throughout the liquefied natural gas (LNG) chain — Part 1: General

ISO 14044, Environmental management — Life cycle assessment — Requirements and guidelines

ISO 14064‑1, Greenhouse gases — Part 1: Specification with guidance at the organization level for quantification and reporting of greenhouse gas emissions and removals

For the purposes of this document, the terms and definitions given in ISO 14064-1 and ISO 6338-1 apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

The principles given in ISO 6338-1 shall be followed.

The GHG report for shipping of LNG shall cover all associated activities. The list in Table 1 is not exhaustive.

The GHG report shall be done over a period (see ISO 6338-1, 6.2.2.2 and ISO 6338-1, 6.4). It shall be done for each ship. It can then be allocated to a cargo including the ballast leg.

Table 1 — List of activities within the scope of this document

The organization having operational control over the ship (operator) shall report all GHG emissions and removals within the reporting boundaries as frequently as required by the receiving body.

The general approach is given in ISO 6338-1. Emissions estimation guidance for LNG shipping can be found in the API Consistent Methodology for Estimating Greenhouse Gas Emissions from Liquified Natural Gas (LNG) Operations (2015).^[24] OGMP 2.0, Methane Measurement Protocol (tbc).

The quantification approaches for emissions from fuel combustion are described in Table 2.

Emissions from fuel production are not covered (tank-to-wake and not well-to-wake).

Table 2 — Emissions from fuel combustion

The quantification approaches for emissions from fuel cells are described in Table 3.

Table 3 — Emissions from fuel cells

The quantification approaches for emissions from venting are described in Table 4.

Table 4 — Emissions from venting

The quantification approaches for fugitive emissions are described given in Table 5.

Table 5 — Fugitive emissions

Emissions associated with imports require data from the exporter or ship operator. Contractual relationship with the exporter or ship operator should include a requirement to provide emissions data. In the absence of reliable GHG data for imports, the calculation shall account for the complete supply chain for the imported commodity. The cut-off criteria for reporting shall be defined in accordance with ISO 14044.

There are no such emissions in shipping.

The calculation of GHG emissions is given in ISO 6338-1.

The preferred units are given in ISO 6338-1. A list of unit conversion factors is provided in ISO 6338-1:2024, Annex A.

The principles and methodology are given in ISO 6338-1.

All emissions are allocated to the LNG shipped. Emissions associated with planned or unplanned maintenance like gassing up or cooling down, etc… (pre/post dry docks) should be spread across next cargoes delivered. These emissions should be identified separately, and applied to subsequent cargoes, allocated to cargoes in the same ratio, and divided across the time to the next such activity. For example, for a 5-year dry docking cycle, 1/5 of the emissions associated with the dry dock activity are allocated to the cargoes per year subsequently.

The opportunities for carbon capture and the quantification of carbon capture benefit are described in ISO 6338-1.

The quality management of the GHG inventory is given in ISO 6338-1.

The reporting of GHG emissions is given in ISO 6338-1.

The independent review of the quantification of the GHG emissions is given in ISO 6338-1.

Bibliography

[1] ISO 6338, Method to calculate GHG emissions at LNG plant

[2] ISO 14020, Environmental statements and programmes for products — Principles and general requirements

[3] ISO 14064‑2, Greenhouse gases — Part 2: Specification with guidance at the project level for quantification, monitoring and reporting of greenhouse gas emission reductions or removal enhancements

[4] ISO 14064‑3, Greenhouse gases — Part 3: Specification with guidance for the verification and validation of greenhouse gas statements

[5] ISO 14065, General principles and requirements for bodies validating and verifying environmental information

[6] ISO 14066, Environmental information — Competence requirements for teams validating and verifying environmental information

[7] ISO 14067, Greenhouse gases — Carbon footprint of products — Requirements and guidelines for quantification

[8] CEN/TS 17874, Methodology for methane emissions quantification for gas transmission, distribution and storage systems and LNG terminals

[9] PAS 2060, Specification for the demonstration of carbon neutrality

[10] EPA AP-42, Compilation of Air Emission Factors

[11] EPA Method-21, Determination of Volatile Organic Compound Leaks

[12] Marcogaz, Recommendations on LDAR campaigns

[13] Methane Guiding Principles, Reducing Methane Emissions: Best Practice Guide Equipment Leaks

[14] API, compendium on GHG methodology

[15] GHG Protocol, Scope 2 guidance

[16] IEA, Yearly report Emission factors

[17] IPCC, Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

[18] IPPC, 6^th assessment report

[19] IOGP report 2.59-197 Method for estimating atmospheric emissions from E&P operations

[20] IPIECA Petroleum industry guideline for reporting GHG

[21] World Business Council for Sustainable Development (WBCSD)/World Resources Institute (WRI). Greenhouse Gas Protocol, Corporate Accounting and Reporting Standard, April 2004

[22] EFFAS THE EUROPEAN FEDERATION OF FINANCIAL ANALYSTS SOCIETIES, Key Performance Indicators for Environmental, Social & Governance Issues

[23] United Nations, Global indicator framework for the Sustainable Development Goals and targets of the 2030 Agenda for Sustainable Development

[24] API Consistent Methodology for Estimating Greenhouse Gas Emissions from Liquefied Natural Gas (LNG) Operations