DNV introduces decarbonization class notation for floating offshore assets

Erik Carlberg * DNV

When the IMO announced its new, more ambitious decarbonization targets for the shipping industry in July 2023, the decision was praised by politicians and the general public around the world. But the regulations in place to achieve these targets, such as the Energy Efficiency Design Index (EEDI), Energy Efficiency Existing Ship Index (EEXI) and Carbon Intensity Indicator (CII), apply to the merchant fleet only. One key parameter in the carbon intensity calculations described by IMO is transport work. Since floating offshore units do not transport any cargo, they are not subject to these regulations.

Floating offshore assets emit significant amounts of greenhouse gases during operation. The type and function of the actual installation, drilling vs production, will of course determine the relevant GHG emission sources.

For a production unit, according to the UK Oil and Gas Authority’s 2021 “Emissions Monitoring Report,” 88% of total emissions are CO₂, followed by CH₄ (methane) at 10%, and N₂O (nitrous oxide) at 2%. The majority of the methane, a powerful climate gas, originates from venting and flaring, whereas most of the CO₂ and N₂O emissions are from fuel combustion in gas turbines as well as flaring.

Meanwhile more major oil and gas companies are setting ambitious environmental and decarbonization goals for their operations to show their commitment to making a difference and are willing to embrace the ESG standards and the 17 UN Sustainable Development Goals. By adopting effective carbon reduction measures, mobile offshore unit (MOU) operators can improve not only their public image but also their access to sources of investment capital as financial institutions are increasingly looking to minimize their exposure to the fossil fuel industry and move into the renewables sector. What is more, carbon trading schemes penalize carbon emissions and act as a financial incentive for operators to minimize their carbon footprint to avoid loss of profitability.

Abatement measures

Decarbonizing offshore oil and gas installations is technically complex and very costly. To help MOU operators and ultimately provide them with a means to credibly demonstrate their commitment to reducing their operational GHG emissions, DNV’s new class notation Abate, introduced in July 2021, defines a framework for identifying, assessing and implementing effective GHG reduction measures. The Abate notation comprises a management aspect (Abate Ready notation) and a number of additional technical qualifiers which can be adopted individually. It can be awarded to a newbuild project or an existing asset. The required emission management system is very similar to the ISO quality assurance, environmental and energy standards, and will therefore be quite familiar to any organization.

The basic scope of Abate requirements includes the assessment of the emissions management system and also involves an assessment of potential abatement measures based on a thorough analysis of the asset and its emission sources. Both are necessary to obtain the Abate (Ready) notation and are prerequisites for obtaining any of the other Abate qualifiers. A dedicated person or team must be put in charge of the emission management system, and an emission abatement policy must be established that specifies realistic emission abatement goals and how they will be achieved.

The more detailed technical scope is reflected in the additional technical qualifiers directed towards specific emission sources. These qualifiers add prescriptive requirements for specific features of a floating offshore asset related to its function, such as power generation (P), carbon capture (CC), flaring (F) and others. Adopters of the class notation are expected to apply state-of-the-art abatement technology. A variety of measures may be taken, again depending on the installation function, such as:

Reducing onboard energy demand
Improving energy efficiency
Optimizing system configurations
Upgrading equipment and control systems
Improving waste heat recovery
Reducing flaring
Capturing associated gas for productive use
Minimizing process and tank venting as well as leakage
Optimizing monitoring, inspection and maintenance regimes
Installing carbon capture and storage equipment.

Whether or not some or all such measures are implemented will be subject to assessment of parameters such as technical feasibility, contribution to emission reduction, and the cost/benefit profile.

Compliance with the agreed scope of requirements, including implementation of the emission management system, proper function of abatement installations, potential further abatement measures, and assessment of the best available abatement technology is verified by DNV through regular surveys.

Early adopters

The first FPSO owner to adopt the DNV Abate class notation was Altera Infrastructure with their FPSO Petrojarl Knarr in 2021. This pioneering project helped DNV, working closely with the customer, to further develop and fine-tune the rules of Abate based on real-life observations.

Additionally, the first jackup unit to receive DNV’s Abate Ready notation was the self-propelled Vahana Aryan, the flagship vessel of the Dubai-based Vahana Marine Solutions DMCC, in spring of 2023.

The Abate Notation provides a structured approach to identifying potential abatement measures which can then be incorporated into a newbuild design.

Of course many offshore operators and contractors have developed their own internal processes, and have their own operational philosophy on how they wish to address the issue.

In many cases, for existing units, the Abate notation can provide a means, by an independent assessment, to give credit to measures which companies have already put in place based on their own emission reduction philosophy, and also then identify potential additional measures which may be feasible to implement.

Since the Abate notation is a modular approach, the initial stage of assessment of the management system and assessment of best available technology may represent the start of the journey in documenting both current status and future intentions. Credit is given for conducting this assessment by award of the Abate (Ready) notation.

By reducing the environmental impact of floating offshore installations, DNV’s Abate Ready class notation thus implies a promise to the industry, the public and the financial sector that the necessary measures are underway.

A number of other MOU owners are about to follow or have indicated strong interest in the Abate class notation. There is particular interest among owners and operators of FPSOs in the Asia region to be at the forefront of these developments and to demonstrate how seriously they are taking the climate challenges that we are all facing. DNV are currently working with many of these owners in ongoing projects to implement the Abate framework, and thereby supporting them to reach their ambitions in reduction of greenhouse gas emissions from their operations.