IMOS - UK ETS in the Carbon Calculator

Introduction

The UK Emissions Trading Scheme (UK ETS) expands to maritime from 1 July 2026. This article summarizes the scheme's scope and compliance mechanics as they apply to shipping, alongside how UK ETS modifiers and carbon pricing are intended to be handled in the Carbon Calculator. Like EU ETS, UK ETS percentages apply to the Carbon Cost calculation per voyage leg, determined by the relevant ports.

This feature requires the configuration flag CFGEnableUkEts to be enabled.

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UK ETS Scope

From 1 July 2026, the UK ETS applies to cargo and passenger vessels of 5,000 GT and above. Offshore ships are brought into scope later, from 1 January 2027. The scheme covers emissions on domestic voyages between UK ports and emissions generated while in UK ports of call.

Phase-in and Reporting Timeline

Unlike EU ETS, which phases in surrender obligations over several years, the UK ETS applies a 100% surrender obligation from the start, but the first scheme year is a half-year.

Period

Notes

1 Jul – 31 Dec 2026

First (partial) scheme year; reporting begins 1 July

2027 onward

Standard reporting year, 1 Jan – 31 Dec


Greenhouse Gases Covered

The greenhouse gases covered align with EU ETS and include combustion and slippage emissions of:

  • Carbon dioxide (CO₂)

  • Methane (CH₄)

  • Nitrous oxide (N₂O)

Emissions are calculated on a tank-to-wake basis. Methane and nitrous oxide are reported using IPCC AR5 global warming potential values: CH₄ = 28 and N₂O = 265. (Note: this is the same GWP convention used for EU ETS and differs FuelEU - AR4)

Domestic Voyages and Ports of Call

A domestic voyage includes any voyage from one UK port to another, as well as a voyage that starts and ends at the same UK port. Emissions generated during ports of call are also in scope, including time at berth, whether moored or anchored, at UK ports and offshore installations.

Because port-of-call emissions are captured, the port stay portion of an international route calling at a UK port is also within scope, even though the international voyage leg itself is not a domestic voyage.

Northern Ireland <–> Great Britain Deduction

Coming Soon - this feature will be available shortly

A 50% deduction applies to the surrender obligation for voyages between Northern Ireland and Great Britain. Port stays in both Northern Ireland and Great Britain remain subject to a 100% surrender obligation.

For comparison, on a voyage between a non-UK port (e.g. France) and Great Britain, the voyage leg carries no (0%) surrender obligation, while the Great Britain port stay remains at 100%.


Configuration Flags

Related Configuration Flags

Name/Flag

Description

Enable UK ETS
CFGEnableUkEts

When enabled, a tab in the Estimate's Carbon Calculator appears to calculate the UK ETS.

*Minimum Schema Required: 502