IMO’s carbon reductions push power limits down

Shaft power limitation (SHaPoLi) or engine power limitation (EPL) is likely to be a popular choice for many shipowners to meet the EEXI requirements. It is a relatively simple and cost-effective solution and should cause minimal disruption to the vessel’s operation.

At MEPC 76 in June 2021, a resolution was adopted that provides guidelines on compliance with the EEXI requirements and the use of a power reserve in limitation devices. Shipowners should be aware of these recent developments and how it affects power limitation arrangements.

Overridable power limits

Both SHaPoLi and EPL systems are non-permanent, tamper-proof, and approved, verified methods of power limitation. The former applies a limit to the maximum shaft power and the latter to the engine power.

A power reserve sits above the maximum power limitation and is only to be used in the interests of safety or saving life at sea. It can only be overridden by the Master or officer in charge of the navigational watch from the bridge without the need for entry into a machinery space (if possible).

The use of the power reserve must provide an alert and be properly recorded in the vessel’s Onboard Management Manual (OMM). The vessel’s Flag State (or recognised organisation acting on Flag State’s behalf) and the competent authority of the relevant port of destination are to be notified without delay.

Impact on power and safety

A key parameter used to calculate EEXI is the maximum engine power (P_ME), which is a percentage of the engine’s MCR – maximum continuous rating.

For overridable systems, the P_ME will be the lower of:

• 83% of the limited installed power (MCR_lim); or
• 75% of the original installed power (MCR)

Remember, classification societies may have certain rules regarding engine and shaft power limitation (e.g. ice class vessels), so always carry out any modifications in full consultation with Class.

For permanently derated main engines with non-overridable power limits, we understand P_ME will be 75% of the new de-rated MCR. Always seek confirmation with Class and check for any NOx recertification requirements that apply to non-overridable arrangements.

Challenges ahead

Ships without acceptable documented proof of their speed ~ power curve from sea trials or model tests may have their reference speed (V_REF in the EEXI equation) determined by a statistical method which imposes a penalty of 5% of speed or 1 knot, whichever is greater. In some cases, this may result in more stringent requirements than the EEDI framework for new ships.

Vessel employment and charterparty issues

Shipowners and operators should consider the effect that power limitation will have on their current and future trading patterns and whether additional or alternative energy saving devices or arrangements will be required to achieve the EEXI requirements.

Furthermore, they should consider the impact of fouling or weather on power margins.

Therefore, we urge our Members to act now and commence EEXI benchmarking of their fleet as soon as possible. This will allow an owner to understand what modifications or changes need to be made to achieve the EEXI requirements when they enter into force in 2023.

This will also help with addressing any potential future charterparty issues. For example, power limitation could impact speed and performance and vessel description warranties; therefore, these will require careful review.

Time charters that span 2023 and beyond may need careful consideration and require re-negotiation and perhaps address matters such as who is responsible for the costs and time involved in carrying out any modifications.

Charterers need to understand their rights and remedies if an owner fails to meet the EEXI requirements or maintain an International Energy Efficiency Certificate (IEEC).

The earlier this process is started and discussions between owners and charterers take place, the better!

Electronic power limitation systems: Q&A with Lean Marine

To find out more about a specific electronic power limitation system, we asked Lean Marine, maritime experts specialising in designing and manufacturing automated fuel-saving, performance management and reporting solutions for vessels.

Have you seen an increase in enquiries from shipowners preparing their vessels for the EEXI statutory requirements?

Yes, indeed! Shipowners, operators, and charterers are requesting more information on our propulsion optimisation system FuelOpt™ and how it can help them comply with EEXI requirements. Fuel efficiency, resulting in emissions reduction, is a top priority for all of them and vessel efficiency enables them to achieve green shipping targets whilst remaining competitive.

What advantages does your system give for power limitation over limiting via the governor or other fixed engine derating measures?

In addition to being compliant with the SHaPoLi requirements, our propulsion automation system dynamically optimises a vessel’s propulsion line in real-time by making sure that the engine and propeller operate at optimal conditions based on the commands or limitations set.

It doesn’t require any modification to existing machinery and can be overridden in an emergency, thereby enabling access to the engine’s power reserve. The same measures can be applied over an entire fleet, regardless of make and model of engines or propulsion control systems.

How else can you use the system data?

Data generated by FuelOpt™ and any information collected from other sources is integrated into the smart cloud-based performance management and reporting system, Fleet Analytics™.

As well as providing voyage reports and data for CO₂ emission reporting requirements (e.g. EU MRV and IMO-DCS), Fleet Analytics satisfies the EEXI regulation which says that shaft power data must be logged and prove compliance. It also provides aggregated fleet views, status insights and allows in-depth analysis for onboard and ashore personnel for voyage and operational optimisation.

The combination of FuelOpt™ and Fleet Analytics™ can also assist a shipping company in its efforts to continuously improve its operation carbon intensity to comply with the IMO Carbon Intensity Indicator (CII) rating scheme.

What is the return of investment (ROI) of your FuelOpt system based on fuel consumption savings?

Most customers are seeing an ROI in less than one year, however some of the larger ferries are reporting less than three months.