Energy saving devices trend report
Key insights:
In 2023, the majority of ship owners who invested in vessel enhancement went for power limitation. This trend represents a missed opportunity, as ship owners miss the many benefits of ESD investment for minimum compliance.
The rest of the investment went to rudder optimisation, hull ducts or fins, propeller boss cap fins, and propeller ducts or nozzles. These are all positive and impactful enhancements.
RightShip is adjusting the requirements for propeller boss cap fins for the GHG Rating. Ship owners and managers will soon be able to submit a structured report and calibration on top of their original sea trial without the PBCF, which RightShip will cross-reference, and then award the 1.5% efficiency gains.
GHG Rating and energy saving devices in the bulk sector
RightShip’s GHG Rating has been providing the commercial shipping market with meaningful insights into the potential efficiency of vessels since 2013. The A-E scale allows selection of the most efficient vessels and facilitates a metric for discussion on collaboration between shipowners, charterers, ports and terminals and finance institutions on their respective decarbonisation journeys.
The rating encourages investment in energy saving devices, driving the industry towards effective decarbonisation measures. RightShip has been gathering data on investments for over a decade and is able to highlight a number of trends. If we take the bulk sector as a focus segment, we can see over the past decade there has been a steady increase in ESD investments.
Propeller boss cap fins
From data submitted to RightShip over the past 10+ years through the GHG Rating review process, we identified propeller boss cap fins (PBCF) improve energy efficiency by approximately 1.5%, a small but significant improvement for a low price. Since the simulated CFD study to prove installation is often more expensive than the installation itself, RightShip is reviewing the removal of this requirement to submit absolute evidence from its GHG Rating for PBCFs. Once formalized, ship owners and managers will be able to submit a structured report and calibration on top of their original sea trial without the PBCF, which we will cross-reference, and then award the 1.5% efficiency gains.
Hull coating
Hull coating and cleaning are direct and immediately impactful ways of reducing vessel emissions. IMO studies suggest that a reduction of as much as 8% in energy is possible with hull coating and cleaning (this goes both for silicone-based and self-polishing types of coatings). However, the total is usually more in the range of 1-4%, with vessel size, segment, operation profile, and trading areas all playing a role. However, the potential is certainly there, and some manufacturers are bullish about the impact of their hull coatings.
Hull coatings can improve hull smoothness and reduce the roughness penalty, which is the increase in resistance due to the deterioration of the hull surface over time. Hull coatings can also prevent or delay the onset of fouling, which is the accumulation of marine organisms on the hull that can increase drag and thus fuel consumption significantly. Hull coatings can also extend the service life of the hull and reduce the frequency and cost of drydocking and cleaning.
Of note are the emerging low-friction anti-fouling (LFAF) paints such as silicone, graphene, etc. The paint’s traditional role in antifouling makes it challenging to communicate their acceptance as a performance enhancing systems like an energy saving device. Such paints work by modifying the velocity profile within the boundary layer of the ship’s hull leading to reduced frictional resistance. However, since a ship’s hull deforms it becomes challenging for paints' effect to be noticed in real sea trials. It is also a fact that paints undergo continuous degradation in service.
RightShip is reviewing such methodologies with Class Societies on how to show such efficiency improvements in the absence of industry-wide guidelines. This will allow us to award a certain percentage improvement in efficiency to the specific vessel on which such coatings are applied through RightShip’s EVDI and GHG Rating system.
The good and the bad in ESD investment
Power limitation and missed opportunities
The impact of power limitation devices as a compliance mechanism for EEXI is quite pronounced with the majority of investments in 2023 being either Engine Power Limitation (EPL) or Shaft Power Limitation (ShaPoLi).
There is a danger that the focus on compliance through EPL is a missed opportunity for achieving the many benefits of ESDs, including impact on GHG Rating and fuel, emissions, and cost savings during operation of the ship. Forward thinking organisations should consider the design of the vessel, and how that interacts with increased costs such as the EU ETS and Fuel EU Maritime.
Increased investment across four categories
When examining ESD investment trends in the bulk sector, it’s clear that there are four investments that are seen as the most favoured: rudder optimisation, hull ducts or fins, propeller boss cap fins, and propeller ducts or nozzles. All of these investments modify the propulsion efficiency and/or hydrodynamics of the vessel thus reducing the fuel consumption and greenhouse gasses emitted over a journey.
In terms of benefits, the main trends from the top four investments can be seen below.
It’s worth remembering that the g/c02/t/nm translate into real operational savings. So, for example simply saving 0.19g of c02 at one tonne one nautical mile will translate into large savings over a long journey These savings should be factored into the cost of fuel, and any liabilities for carbon emitted through ETS and Fuel EU maritime policies. Below is an estimate of the vessel sailing at design optimum conditions which is shown as a guide. We can calculate the estimated C02 based upon EEDI using the formula
Estimated emissions (tonnes) = EEDI X DWT X nautical miles / 1,000,000 (1 tonne = 1,000,000g)
We can then compare the potential savings on a 10,000-mile journey for a 200,000 DWT vessel for a vessel that has and hasn’t invested in an ESD that provides a 0.15g saving at optimum design efficiency. This translates into a potential 300 tonnes of emissions saving, €22,500 at current EUA price of €75 and €98,750 in fuel costs (MGO). Of course, the operational reality of savings needs to be tracked to verify the investment but the potential in just a small saving is there to be seen.
EU ETS: 300t emissions savings @ €75 AN EUA = € 22,500 potential saving in Carbon Tax
Fuel Saving: Estimated 125t @ €790/t MGO = €98,750 potential saving in fuel cost.
(Note: the above is for illustration purposes in perfect conditions)
This exercise could be undertaken for various technologies to understand the impact and the benefits of investment on individual transit legs and across time charters. Finally, with the advent of technology with even larger impacts on EVDI and efficiency, such as WAP and low friction anti-fouling paint which has the potential for even greater savings forward thinking shipowners should be considering the holistic picture for their investments.
Conclusion
For ship owners, it is worth monitoring these trends and considering investment in such ESDs to go beyond compliance of EEXI. This offers the benefit of design efficiency, which, as stated, translates into real-world operational savings on fuel, emissions, and emissions costs to the planet and the pocket.
This will help the journey of decarbonisation by bending the curve towards net zero 2050, and lock in learnings of more efficient vessels ahead of the fuel transition.
