In international shipping news, shipping: possible emissions 13/09/2021

How can the shipowner comply with the existing ship energy efficiency index (EEXI) and increase the ship’s carbon intensity index (CII) without reducing the sailing speed? In this article, we will take a closer look at potential ways to comply and alternative technologies that can be used to improve energy efficiency.

In June of this year, the Marine Environmental Protection Committee of the International Maritime Organization (MEPC 76) adopted a number of technical and operational measures aimed at reducing the carbon intensity of international shipping. These measures are applicable from 2023 and include the Energy Efficiency Index for Existing Ships (EEXI), which defines the minimum energy efficiency level of existing ships, and the Carbon Intensity Index (CII) rating plan, which provides annual ratings of ships from A to E The carbon intensity of A is the lowest.

It is believed that most shipowners will seek to comply with EEXI by adopting engine power limitation (EPL) or shaft power limitation (ShaPoLi), the latter may be the first choice for multi-engine settings. Regardless of the route chosen, the result will be a reduction in the power delivered to the propeller, which will have a potential long-term impact on the economic performance of the ship.

Although for ships with high installed power and high design speeds, reducing speed may be an effective option, but for ships aiming to sail at much lower speeds, such as tankers and bulk carriers, EPL and ShaPoLi solutions The advantages in business flexibility may be limited and attractive to tenants.

Wärtsilä recently worked with a customer to check the operation of one of its bulk carriers in the past 12 months. In this case, although the 5% speed reduction of EPL is acceptable when considering the average ship speed, when the ship needs to sail at a higher speed, it will affect approximately 15% in a 12-month period. % Of the ship’s sailing days. Another limiting effect of EPL and ShaPoLi is that they will not have any actual impact on the ship’s carbon footprint, so there is no benefit to the ship’s CII rating.

So, what are the alternatives and how can ship owners improve their EEXI without reducing the sailing speed?

ESD has a direct impact on ship propulsion efficiency by reducing hull resistance and increasing propeller thrust. Wärtsilä offers pre-swirl and post-swirl devices, such as Wartsila EnergoFlow and Wärtsilä EnergoProFin, as well as high-performance hull coatings to reduce drag and fouling. The installation of replacement propellers optimized for the current operating conditions of the ship also has significant potential advantages. Depending on the type of ship, combining ESD and optimized propellers can achieve 5-10% energy savings. The problem is that many newer ships have already installed ESD, so there is limited room for improvement. For this reason, we may see alternatives to ESD, such as air lubrication systems and wind rotors-which are also part of Wärtsilä's product portfolio-continue to gain traction on the market.

Shaft generator systems have been in existence for decades, aiming to meet the ship’s electricity needs when the ship is sailing by using the main engine instead of the auxiliary engine. With the help of modern converter technology and software, these systems can generate electricity over a wide range of engine speeds. As they have a positive impact on the energy efficiency design index of ships (EEDI-the corresponding index for newbuildings EEXI), they have now become standard equipment for most newbuildings, and as the EEXI deadline is approaching rapidly, the demand for retrofits in the market has increased significantly as well as.

Shaft generator systems have the potential to increase the energy efficiency of ships by 3-5% and reduce fuel costs and operating costs. For bulk carriers or oil tankers, the return on investment of shaft generator systems is usually about five years. As the frequency increases, the period becomes shorter and the number of days increases. For existing ESD ships, shaft generators are generally regarded as the second best technology option to achieve EEXI compliance while reducing OPEX and positively impacting CII ratings. There are currently more than 550 sailing ships benefiting from the Wärtsilä shaft generator system.

Hybrid systems usually combine energy storage systems and traditional engines. It can be used as a standard solution for new ships or as a retrofit solution for existing ships. Wärtsilä has been experimenting with hybrid systems since 2011 when it started at sea, and is now the market leader in hybrid systems for newbuildings and existing ships.

Although the modification has obvious advantages for ships with dynamic positioning systems, and the total fuel consumption can be reduced by up to 20%, the advantages for merchant ships are not so obvious. The hybrid power system can optimize the utilization of auxiliary engines of merchant ships and reduce operating time by introducing start-stop logic and optimizing fuel consumption.

One thing to note is that the EEXI formula has not yet considered the benefits of a separate hybrid system because it does not reduce the total installed power.

When hybrid systems are intended to be part of "free power technology" installations (such as photovoltaic cells), the EEXI impact can be expected to be 4% and a very good return on investment. In addition to the above-mentioned on-board energy optimization, in this case, the hybrid system aims to achieve a higher level of optimization by combining the functions and productivity of solar power generation with the on-board auxiliary engine, and using the battery as a storage buffer. Wärtsilä is currently piloting such a system.

In addition to saving energy immediately, hybrid power should also be seen as a bridge to the future. New power generation technologies, such as fuel cells and engines that can run on cleaner future fuels, may require hybrid system integration to ensure safety and operational stability, especially under transient load conditions or when connected to a port shore power system .

Although the fuel of the future will play a key role in helping the maritime industry to achieve the IMO's goal of reducing the carbon intensity of international shipping by 40% by 2030, the road ahead is full of uncertainty.

LNG is both an established reality for new markets and an excellent choice for retrofitting; it can immediately reduce CO2, NOx, SOx, and particulate matter emissions. It is a recognized marine fuel in almost every field of ships in the world, with a mature legislative framework and a strong refueling infrastructure.

Methanol is currently attracting a lot of attention as an alternative fuel for new construction and renovation. The physical properties of methanol make it an attractive option, and the use of hydrogen from renewable electricity and recycled carbon to make green methanol will neutralize its carbon.

Wärtsilä is one of the few marine engine manufacturers with methanol engine experience. In 2015, a project to retrofit the Wärtsilä Z40 engine to the Ro-Ro ship Stena Germanica to burn methanol was started. The engine now runs mainly on methanol, and the successful installation inspired Wärtsilä to further study this fuel. Learn about Wärtsilä’s overall marine methanol conversion.

In the long run, ammonia and ultimately hydrogen represent the future 100% carbon-free fuel. Interest in these fuels is increasing, and Wärtsilä has established itself as a technology leader. Learn more in our in-depth article on ammonia as a marine fuel.

Obviously, all of these future fuels will have a significant positive impact on the ship’s EEXI and CII ratings. However, their implementation requires substantial investment in refueling infrastructure and on-board fuel storage and processing systems.

In the discussion around decarbonization, shipowners and operators are faced with a series of choices in energy-saving hardware and software. But sometimes one basic thing is overlooked: to ensure that the engine itself runs as efficiently as possible. Wärtsilä’s series of life cycle service agreements are designed to provide appropriate service levels to ensure this.

The starting point for achieving optimal engine performance (thus minimizing emissions) is to ensure that the power system settings match the ship’s operating conditions. Engine modification and engine operation improvements can save a lot of fuel, thereby significantly reducing emissions. It is also important to ensure that these assets are properly maintained. Every component can play a role; for example, replacing the filter or cleaning the air cooler at the right time can help reduce fuel consumption. Data collection and expert analysis can be used to determine the best timing for such maintenance interventions.

The Wärtsilä Life Cycle Agreement provides different levels of support according to customer needs, but all agreements are based on reliable and actionable data. The three-tier combination of rule-based restrictions, anomaly detection, and human expertise allows our customers’ assets to not only maintain normal operations, but also operate in a way that helps, rather than weakens, the ship’s overall decarbonization efforts.

The four approaches discussed in this article—ESD, shaft generator systems, hybrid power, and future fuels—can help shipowners comply with EEXI without requiring them to accept speed losses; in addition, they also improve the ship’s performance by reducing the carbon footprint. Carbon intensity index rating improves its reputation in the eyes of investors and financial institutions.

Read our insight article on LNG conversion to learn about methane-fueled ships reducing greenhouse gas emissions.

Watch our webinar to learn how Wärtsilä can improve fuel efficiency and reduce greenhouse gas emissions by reducing methane leakage. Source: Wärtsilä