Maritime Decarbonization in 2023: Energy Optimization Trends

By Yuhan Ma Published on Jun. 29, 2023

The International Maritime Organization (IMO) has established new regulations with the goal of reducing emissions by at least 40% by 2030 and pursuing 70% by 2050 compared to 2008 levels. As part of its strategy to move toward carbon neutrality, the IMO aims to accelerate decarbonization in 2023.

From January 1, 2023, all ships must calculate their attained Energy Efficiency Existing Ship Index (EEXI) to measure their energy efficiency. They'll also need to initiate the collection of data for the reporting of their annual operational carbon intensity indicator (CII) and CII rating.

Decarbonization will be the central theme of the maritime industry in 2023. To decarbonize, ship owners and operators must look to energy optimization initiatives and utilize alternative fuels or advanced fuel technologies. These innovations are gaining traction as the industry moves toward a more sustainable future.

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Energy optimization trends in maritime

Vessel design

The vessel's design is one of the most important factors when considering energy optimization. It affects the fuel needed to move a vessel through the water and the waste/emissions created in the process.

  • Hull design: Developing a more hydrodynamic and efficient hull is one way to reduce the fuel used. To reduce resistance, engineers and naval architects use advanced computational tools and physical models to design and optimize the hulls of ships to minimize resistance and maximize efficiency.
  • Hull coating: Coatings are applied to the hull of a vessel to reduce fouling and drag, which reduces the load on the engine and therefore leads to an improvement in fuel efficiency. This type of paint is specially designed to reduce the drag created when the boat moves through the water. The result is less energy needed to propel the vessel.
  • Onboard Carbon Capture and Storage (OCCS): This technology captures CO2 directly from ship exhaust and stores it onboard. Many countries and organizations see carbon capturing as a way to reach net-zero emissions while still using carbon resources. However, OCCS has not been widely deployed due to a lack of commercialization and high cost, and it is seen as a temporary solution. Today, the cost of implementing OCCS is decreasing as the cost of emitting CO2 increases, making it a more viable investment.

Operational improvements

  • Route optimization: Many shipowners are looking to use dynamic positioning systems to help optimize the route of their ships and reduce fuel consumption. These systems use predictive algorithms. They examine a vessel’s speed, weather conditions, waves, and currents, among others, to recommend the most efficient route and assist the captain in sailing in a more energy-efficient way.
  • Hull cleaning robotics: These robots are used to clean boat hulls, which reduces drag and improves fuel efficiency. The robotic cleaners use advanced technology to scrub the hull of a vessel. They remove fouling with minimal environmental impact.

Alternative fuels and propulsion systems

  • Wind-Assist propulsion Systems (WAPS): Wind power applications are becoming more popular as energy optimization efforts increase. These systems use wind energy and traditional propulsion to move vessels. Unacknowledged outside the industry, wind-assisted technology is racing from experimental to everyday use. Currently, shipowners have a choice of six different systems. These include rotor sails, hard or rigid sails, soft sails, kites, suction wings, and turbines. This decarbonization innovation reduces fuel consumption and provides a more efficient way to travel long distances. Watch this video to learn how a U.K. research team is developing this technology.
  • Electric or hybrid engines: Electric engines are powered solely by batteries, while hybrid engines use diesel and electricity from batteries. Hybrid engines offer superior efficiency over traditional fossil fuel-powered vessels and lower emissions levels. But their range is limited by the availability of charging infrastructure.

Find out more about upcoming maritime trends in this video:

Current alternative fuels for decarbonization and energy optimization

The shipping industry is on its path toward more eco-friendly and renewable fuels. They're expected to eventually be used instead of traditional fossil fuels like diesel or gasoline. Alternative fuels can be divided into two categories, bridging fuels and future fuels. Bridging fuels are considered short-term and medium-term alternatives for heavy fuel oil. These fuels have the potential to reduce greenhouse gas emissions by a substantial amount, dependent on the production method. However, these fuels will always cause GHG emissions somewhere in their lifecycle and are therefore considered a bridge toward net zero-emission fuels. Future fuels, on the other hand, have the potential to completely avoid the emission of greenhouse gasses over their lifecycle, again dependent on the way they are produced.

Bridging fuels

  • Biofuels: Biofuel is a fuel made from biomass - organic material derived from living organisms - or its byproducts. It can be produced in liquid or gas form and used as a substitute for traditional fossil fuels. They’re considered renewable because they can be regrown or recycled from waste products. Biofuels can be used in existing diesel engines with little or no modification. As a result, they can be used to keep older ships running and complying with the new regulations for some time.
  • Methanol: Methanol is a liquid fuel and the simplest alcohol molecule with the highest ratio of hydrogen to carbon of any other liquid fuel. It is the lightest and lowest-carbon option available. Methanol is a fuel that can be produced from renewable sources. It can be stored in liquid form, making it easier to transport and use. There is already an established infrastructure for converting methanol into power, and it has low pollutant emissions.
  • Natural gas: Natural gas, including liquefied natural gas (LNG) and compressed natural gas (CNG), is a matured alternative fuel option. It produces fewer emissions than traditional fossil fuels, making it a more eco-friendly option. However, it's still a non-renewable resource, and some technology choices need to be made depending on specific vessel designs and operations.

Future fuels

  • Ammonia: Ammonia is a potential zero-carbon fuel cheaper and easier to store than hydrogen or LNG, as it is a liquid under ambient conditions. It produces no greenhouse gasses when it’s completely combusted or when it’s used as a hydrogen carrier. However, it's highly toxic and must be handled carefully.
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  • Hydrogen: Hydrogen is produced from a renewable energy source and is one of the cleanest alternative fuel options available. Hydrogen can be used directly as a compressed or liquified gas and in existing engines with little modification. However, it's expensive to produce and store. The infrastructure for producing and distributing hydrogen is currently limited.

As a transition fuel, liquefied natural gas (LNG) is currently the dominant alternative fuel used in the industry. The ultimate goal is a transition towards ammonia, hydrogen, and battery or hybrid, dependent on the route and vessel type operated.

Maritime decarbonization startup innovations


Maritime decarbonization startups are working on developing solutions to reduce emissions and move the industry away from traditional fossil fuels. These innovative solutions will play a significant role in realizing carbon neutrality in the industry.

  • Innovative coating:Silverstream is using air lubrication as a new type of hull coating to reduce friction between the hull of the vessel and water. Its patented technology shears air from air release units (ARUs) in the hull to create a uniform carpet of microbubbles that coats the full flat bottom of a vessel. As a result, frictional resistance is decreased. Graphite innovation & technology is a Canadian startup that developed technologies allowing their coating to self-clean and reduce drag caused by biofouling effectively. Its marine coatings are free of harmful toxins and biocides, entering the industry with environmentally friendly solutions.
  • Ammonia as alternative fuel:Amogy is building a novel portable carbon-free energy system using ammonia as a renewable fuel. It believes that this new energy system will enable the decarbonization of commercial transportation.
  • Carbon Capture Utilization and Storage (CCUS): Carbon Ridge's Onboard Carbon Capture and Storage (OCCS) solution is unique compared to conventional CCS technology for stationary emitters. It requires an alternative approach to point-source carbon capture. Carbon Ridge's systems are modular and externally mounted on board vessels. It captures CO2 from the exhaust systems and stores it in liquified tanks. Another startup within this field is D-CRBN. The company is using the Carbon Capture and Utilization (CCU) principle. The startup is based in the Port of Antwerp-Bruges and recycles captured CO2. It's then split into carbon monoxide (CO). The CCU process creates new value-added products such as e-fuels, polymers, and chemicals. Therefore, a harmful gas that causes climate change is turned into a business opportunity.

In 2023, decarbonization and energy optimization in the maritime industry will be a significant focus. The decarbonization trends will create new opportunities in the maritime industry, such as using alternative fuels and carbon capture technologies. Shipping companies investing in decarbonization efforts can help them remain competitive in the long term. Ship owners must stay informed if they're to embrace it as part of their operations. They'll also need to understand the potential benefits decarbonization offers.