2030 – Shorter Term Targets

Frictional resistance hinders a ship from moving through the water. It can be reduced by injecting air bubbles between the stationary and moving water (turbulent boundary layer). This will assist in reducing fuel consumption and CO₂ emissions.

In a similar way to modern cars all electric and hybrid ships use Lithium Ion(Li-ion) batteries for energy storage. This contributes to reductions in emissions. The cost of batteries and installation is high and until battery technology is further developed may be seen more on small, short sea vessels.

This is a technology which has been mostly seen in shore power plants and is at very early development stages for ships. Up to 90% of the CO₂ emissions from fossil fuels can be captured. However suitable storage tanks are needed to transport the very dense carbon dioxide to the specially selected underground geological rocks which are used for long term storage.

These are energy saving devices (ESD) aimed at improving a ship’s propulsive efficiency. There are many different designs which can be positioned ahead of the propeller on the ship’s hull or behind it on the rudder or propeller hub.

The Mewis duct, for example is positioned in front of the propeller along with an integrated fin system. Forward thrust is created as the duct straightens and accelerates hull wake into the propeller.

Some makers claim energy efficiency gains up to 8% but this depends on the type and service speed of the vessel.

A fuel cell provides an electrical output in a similar manner to a battery. However, it does not run down or need charging and has a higher power density and lower weight than batteries.

Hydrogen is fed to the (–) anode, and oxygen is fed to the (+) cathode.

The platinum catalyst activates the hydrogen atoms/molecules to separate into protons (H+) and electrons (e–), which take different paths to the (+) cathode.

The electrons go through an external circuit, creating a flow of electricity which can be used to power smaller vessels such as ferries and river vessels. They can also be used for auxiliary loads on larger vessels or providing shore power to docked vessels.

The high costs of hydrogen as a fuel and the bespoke vessel and storage tank requirements mean that this lower carbon option may need to be incentivised before it’s used more. Fuel cells have been used for small ferries as part of a hybrid system with batteries.

As the name suggests optimisation means finding the best solution with many variables. It can be applied to all vessel types and ages. However, there is a larger potential for saving where the expected operating profile differs from the standard design. A container ship, for example may have been designed for a service speed of 22 knots at a fixed draft. If continued slow steaming is required at less than 16 knots, then hull form and propeller optimisation may be required to gain the best efficiencies which in turn will reduce emissions.

A comprehensive series of model tests and computational fluid dynamic (CFD) assessments are needed to optimise a hull form. In some cases, the costs for this may be in excess of 100,000 USD so by arranging this for a group of Sister vessels it may spread the cost.

Hybrid is a merge of an electrical and mechanical source of rotating energy. There are many different types of hybrid systems in use for ships. But the common denominator is usually lithium ion (Li-ion) batteries. Batteries may be fitted for energy storage to work alongside internal combustion engines or in rare cases hydrogen fuel cells where the batteries are secondary to the main engines and generators.

Power demands placed on ships vary dependent on their mode of operation. The type and trade of the vessel also plays a big part in this. If cargo is carried there may be high load at sea and when coming in and out of port for bow thruster and starting air compressor operation. For typical mechanical propulsion systems with one or two main engines directly connected to the propeller batteries may provide little in the way of fuel savings. However, power take off (PTO) and power take in (PTI) may be useful here.

PTO systems have been around for some time and a shaft generator is a classic example. The propulsion engine’s power is transferred into the electrical network via gearboxes and generators. The stored electrical power can be used in lieu of starting another generator which reduces emissions.

PTI works as part of the propulsion system and more like the operation of a hybrid car seen in the 2020’s. Fully electric mode can be used for limited periods in lower power ranges as an emission free option. Hybrid mode can also be used to add propulsive engine performance where extra power is required.

Hybrid technology is seen more in smaller vessels and ferries at present but as battery technology improves, we may see this being developed for other types of larger ships.

In the same way that an electric car needs re-charging to continue so does a full electric propulsion ship. This can restrict trading patterns for obvious reasons and means that ferry operations such as Fjord crossings with few variables and repeated nature are feasible if there is a suitable infrastructure on shore for charging between crossings. Class rules dictate that there are two independent battery systems so that there is a back-up if one fails.

Batteries can be charged by an AC/DC converter which can be located either on the vessel or ashore.

The below diagram shows a typical layout of battery propulsion for an all-electric ship.

Waste heat recovery systems convert thermal energy from exhaust gases into electrical energy. An exhaust gas boiler may be assisted by an oil-fired boiler to drive a power turbine and /or steam turbine which in turn rotates an alternator.

It’s important to note that waste heat units can be retrofitted, but the cost of fitting, weight of additional machinery, pipework, controls and maintenance costs all need to be factored in.

A container ship, for example which was built with a service speed of 22 knots and now slow-steaming at around 17 knots may not benefit as much from waste heat recovery because of all of the heat from the exhaust gases may be needed for fuel heating or other equipment in colder climates.

There is a potential for a reduction in main engine fuel consumption up to 8% which contributes to emissions reductions overall.

A ship with a lower friction hull coating reduces drag which results in lower fuel consumption and reduced CO₂ emissions. This has always been the aim for hull coatings but recent products such as Nippon paint’s A-LF-Sea (advanced low friction) have brought this onto the next level. The concept was inspired by tuna fish and means that the hull coating uses a hydrophilic compound called hydrogel. The science behind this means that the hull coating traps a layer of sea water into the surface membrane. This reduces friction by increasing the hull’s boundary layer.

Shore power is sometimes referred to as cold ironing. Below you will see a brief description of what’s involved and where it may be used.

When a ship is in port it no longer needs propulsive power. However, many different types of vessels still need energy in port for pumps, control systems, cargo handling systems, heating, cooling, ventilation and IT systems as well as domestic use. Generators are commonly used to provide the required power in port. However, use of shore power may prevent localised noise and air emissions created by generators. Dependant on the energy source shore power may also reduce CO₂ emissions overall.

Smaller vessels with power requirements below 100 KW can make use of normal grid voltage and frequency and a small investment may only be required. For larger vessels up to as much as 15 MW with high power requirements it gets far more complicated with a higher expense.

The required modifications to serve higher power vessels on land and ashore include but are not limited to upgrading grid capacity, frequency converters and complex, high-power connectors. This reduces the amount of ports and ships which can make use of shore power.

It should also be considered that this will only reduce fuel consumption whilst the vessel is in port so recharging of batteries may be possible in addition to supplying power but for larger vessels with internal combustion engines fuel consumptions in port will only represent a very small proportion of fuel used overall. This may translate to a smaller reduction in Co2 emissions when you consider the trading pattern of the vessel.

It may be feasible to provide small amounts of AC or DC power to certain types of ships including car carriers, bulkers, passenger ferries and smaller domestic vessels by using marine grade solar panels. However, this may not suit container vessels because of the space required.

This technology is in its infancy and there are certain development projects also considering the fitting of marine grade solar panels onto the sails to combine solar and wind power.

Sail power on its own will not be the magic solution in achieving a zero-carbon means of propulsion. But if harnessed, wind-assisted propulsion can reduce a vessel’s fuel consumption, resulting in lower GHG emissions. The difficulty of course is harnessing the power of the wind, which seafarers have been tackling for millennia.

Modern wind propulsion comes in a variety of forms and some are already being used on cargo ships at sea.

There are many different types in this North article giving more info on this.

DNV have predicted that ammonia will be the most popular of the alternative fuels by 2050.

Like hydrogen, most ammonia is currently made using natural gas. For it to be a viable option, it must in the future be manufactured through low-carbon processes. Ammonia can be burnt in dual-fuel internal combustion engine (MAN B&W report only minor modifications to its LPG fuelled engine are required) or as the energy source for fuel cells.

There is precedence on using ammonia on vessels, but this has been limited to its use as a refrigerant. The concerns on its toxicity are well-known and it requires careful handling.

Biofuels can be blended with traditional crude-derived marine fuel oils or used as a ‘drop-in’ fuel, where they act as a direct substitute.

There are numerous biofuels, all derived from various feedstocks through different processes. Two of the more well-known biofuels whose use may become more widespread include heavy vegetable oil (HVO) and biodiesel (FAME, fatty acid methyl ester). Both are sourced from vegetable oil crops but through different processes.

There are several significant barriers to the widespread adoption of biofuels – the nature of which are environmental, economic and technical. For example, fuels must be sourced from sustainable feedstocks if it is to be a ‘green’ option. Also, there is competition for the oil crop feedstocks from the food, cosmetics and pharmaceutical industries. Furthermore, there are long term storage issues with some biofuels, especially if they come into contact with water.

Hydrogen as a marine fuel

As the maritime industry looks for zero-carbon fuels to replace traditional fossil-fuels, hydrogen has emerged as a serious contender.

Whether it can be a true zero-carbon fuel on a lifecycle (or ‘well-to-wake’) basis depends on how the hydrogen is derived.

While hydrogen has the potential to be a truly zero-carbon fuel, it is not without its hazards and challenges.

Here, we take a closer look at hydrogen and how it can be used as a marine fuel.

Hydrogen Production methods

Below is a schematic showing more information on the hydrogen production methods.

• The above is a basic guide open to interpretation and subject to change
• Pink and purple Hydrogen are different names for the same process.
• Brown and black carbon is effectively the same but the type of coal burnt differs.
• In some cases fossil fuels are used to produce yellow hydrogen

Hydrogen properties 

• Very buoyant and much lighter than air
• It’s non toxic and does not contaminate the environment or threaten humans or wildlife.
• Low energy density – requiring a lot of storage space which may reduce cargo carrying capacity

Hydrogen – dangers

• Highly combustible, explosive gas, invisible and tasteless
• Very wide flammability range – ignited at 4-74% concentration in air by volume
• Bunkering operations – may require specific risk assessments and safety zones

Safety Systems – required

The below is an example of some of the safety systems required. Please consult with your Classification Society for further guidance.

• Emergency shut downs
• Double walled system – ventilation
• Leak strategy sensors
• 3 layer safety system

Safety planning

Guidance by the owner’s Classification Society is required. Below are some points to consider at the planning stage.

DNV strongly predict LNG will be the transition fuel of choice. Comprising mostly of methane (CH4), LNG is already being adopted by an albeit small proportion of the world fleet. It is an attractive option because of its zero-sulphur content (satisfying the IMO 2020 sulphur cap) and its CO₂ emissions are approximately 20% lower than that of distillate fuels (such as MGO) and the new VLSFO products.

However, LNG as a marine fuel is not without its drawbacks. Bunkering, storage and handling takes much more care and presents very different risks to those of traditional marine fuels. Making a vessel LNG-ready requires significant investment – from installing gas (or dual fuel) engines, to additional storage requirements. Also, the global warming potential (GWP) of methane is more than twenty times that of CO₂ , which will be an issue if excessive ‘methane-slip’ is experienced in the engines.

The definition of liquified petroleum gas (LPG) is a mixture of propane and butane in liquid form. A tank of LPG will typically be three times the size of a tank containing oil-based fuel so needs to be factored into the design of the ship.

LPG can be used in dual fuel internal combustion engines (two and four stroke) with pilot ignition. It can also be used with gas turbines.

LPG has a higher density than air which may create a danger if it leaks in lower spaces.  This places extra focus on leak prevention and suitable ventilation. The flashpoint of LPG is also very low, and this means that double walled pipelines are required in the engine room with suitable leak detection equipment. The IGF code mandates a risk-based design approach which can be quite time consuming and expensive.

When considering CO₂ emissions on a well to wake basis LPG is not as low as LNG but lower than oil-based fuels.

In a 2019 DNV article they advised that LPG may act as a suitable bridging fuel to ammonia since LPG installations in a ship may be suitable for ammonia too.

Currently, methanol is produced using natural gas feedstock, and as such it provides only a very modest reduction in CO₂ emissions compared to traditional marine fuels. However, methanol derived from biomass can bring up to a 50% reduction.

Mostly used in the chemical industry, methanol is gaining popularity as an automotive fuel in China.

Methanol is a liquid at ambient pressure and temperature. This makes storage and handling much simpler compared to many of the other alternative fuels.

In 2018 AIS provider Marine Traffic provided statistics to show certain types of vessels spending between 4% and 9% of the year at anchor. By reducing this down time and optimising connectivity between ports, carriers and ships there are some gains to be made which will reduce bunker consumption and in turn reduce GHG emissions.

A Just In Time (JIT) arrival guide developed by the IMO’s Global Industry Alliance to support low carbon shipping (Low Carbon GIA) has been developed. It documents the findings of a series of roundtables which brought together nearly 50 companies and organisations which are key stakeholders in the port call process.

The purpose of the JIT arrival guide is to provide information and proposals to the port and shipping sectors as well as maritime administrations on how to facilitate JIT arrival of ships to reduce GHG emissions. This could be achieved by optimising the port call business process and providing sustainable solutions to customers in the end-to-end supply chain.

The JIT arrival guide is useful for shipowners, ship operators, charterers, ship agents, shipbrokers, terminals, port authorities and marine service providers. There are also other relevant stakeholders. The combined efforts help to communicate and make the required changes to achieve JIT arrival from a port perspective.

JIT is useful in all sectors of shipping; however, it’s suggested that early efforts are made for container vessels because liner trades are more predictable. Wet and dry bulk sectors may follow next.

Voyage optimisation is key to operational efficiency. Safe operation, fuel efficient voyage planning, weather routing, ballast and trim optimisation as well speed setting all play a part. Even rudder and auto-pilot operation are an area of focus. Some of the larger container carriers operate fleet efficiency centres and departments using a holistic approach to monitor and assist on a global basis.

To ensure the vessel sails through the water efficiently it’s important to ensure hull coating is optimised and there is no fouling or detachment. This needs careful monitoring with dive teams inspecting the coating of vessels who appear to be consuming more fuel than they should and/ or experiencing high slip.

This all contributes to the Ship Energy Efficiency Management Plan (SEEMP).

Remote data is sent from ships to a portal where users can access diagnostic and efficiency reports. Fuel reporting including consumption and many other engine and operating parameters are transferred. This can assist with optimising fuel consumption and comparing similar vessels in the Fleet against sea trial data.

By remotely monitoring engine status and running hours it’s easier to avoid failure caused by overdue or unplanned maintenance. This then reduces downtime which means that the ship can work more efficiently with port schedules being more accurate.

In some cases, Masters, Chief Engineers and officers do not like their ships and equipment being remotely monitored and feel it questions their professional judgment when shore personnel question certain elements. However, it has been proven beneficial in improving efficiencies by many large companies.

Safety of the vessel, crew and cargo is of paramount importance and weather routing can assist with suitable voyage planning in this respect.

The IMO stated that weather routing reduced fuel consumption by between 2 and 4% as far back as 2008 (MEPC58/INF.31). This reduction can be even greater on large container vessels.

In some cases, the shortest distance between two points may not be the fastest or use the least amount of fuel because of currents, wave heights or winds. By allowing ship and shore to see the same accurate route and weather data it’s easier to ensure a safe, fuel efficient and compliant voyage takes place. This will contribute to a reduction in CO₂ emissions.

This a mandatory system for fuel oil which entered into force on 1 March 2018. Ships of 5,000 GT and above are required to collect consumption data for each type of fuel they use as well as other specified data relating to transport work. After 31^st December 2018 ships of this size would need to include in their Ship Energy efficiency management plan a description of the methodology used to collect the data and the processes used to report same to the ship’s flag state.

More information can be found on the IMO website here.

As part of the European Union’s action to tackle greenhouse gas emissions from shipping, the EU MRV Regulation requires shipowners and operators to monitor, report and verify CO₂ emissions from their vessels calling at EU ports.

Many shipowners are beginning to focus their efforts on decarbonising their fleet as we move towards 2030 and 2050 in line with IMO policies and ambitions. But with the introduction of the Sea Cargo Charter, cargo interests and charterers can play an important role too.

The Sea Cargo Charter (SCC) provides a framework that enables shipowners, charterers and cargo owners in the bulk industry to align their activities and promote shipping’s green transition.

The maritime financial sector has recognised the importance of its role in ensuring responsible environmental stewardship and has created the Poseidon Principles.

This is a framework for financial institutions, banks, lenders, vessel mortgagees, guarantors etc. to make sure their portfolios are aligned with environmental principles – in particular, the IMO’s GHG targets for 2030 and 2050.

Thirteen leading banks, who between them represent about US$ 100 billion in shipping finance, have publicly committed to measuring the carbon intensity of their portfolio on an annual basis and to report on whether decarbonisation efforts are on track.

Poseidon Principles shouldn’t prove to be a further administrative burden on ships’ crews. Data will be collected from the IMO Data Collection System (DCS), so there shouldn’t be double reporting.

The simple message from these financial backers of the maritime industry is that they may move away from shipowners whose fleets aren’t decarbonising at the rate needed to meet the IMO targets.