What is the fuel of the future shipping?

Next winter will be difficult throughout Europe. The prices of fossil fuels, coal, gas and electricity have skyrocketed as a result of the war in Ukraine. On the other hand, the increase in the price of fossil energy accelerates the development and introduction of renewable forms of energy.

Different alternative fuels are also constantly brought in for testing in shipping. With the rise in the price of traditional heavy fuel oil and LNG, alternative fuels have become more and more economically viable – almost every day we read how shipping companies are planning to introduce new low-carbon fuels. In this case, a distinction must be made between where the energy was originally produced and what form it was then transformed into so that it can be used at sea.

Shipping companies switch to low-emission fuels

The first and often the most important measure in reducing maritime carbon emissions is energysaving. These measures include lowering the sailing speed, often combined with speeding up the operations in the port, increasing the payload of vessels and reducing ballast voyages. Other significant actions are various technical aids, such as wind rotors and reducing the resistance of the hull, etc.

In the end, however, we come to the question of what is the non-fossil fuel to which shipping is moving. There is still no unequivocal answer to this question, but it is gratifying how many pioneering shipping companies have already announced that they are testing new fossil-free fuels. The following shipping companies have already announced their development path:

• Finnferries has already brought two electric ferries into Finnish traffic, there are also many similar small ferries in use in other Nordic countries.

• Stena is planning an electric ro-pax vessel.

• Meriaura has announced that it will start developing an ammonia-powered ship.

• Viking Line plans to switch to carbon-neutral traffic between Finland and Sweden with the help of biofuels.

• In London, in addition to electricity, city waterway traffic is moving to vegetable oil-based biofuel.

• ESL Shipping plans to use renewable biofuel already in the current traffic and plans to switch to using hydrogen-based fuels in the future.

• Aurelia Green Ship Concept aims for a hydrogen powered ship.

• However, the world’s largest shipping companies, such as Maersk and COSCO, seem to be investing in methanol as their future fuel.

What should be taken into account when choosing fuel?

The choice of fuel is naturally influenced by the price of different fuels in the future, and what the use of that energy form costs compared to, for example, the fuels currently in use. However, this is far too narrow a perspective.

The matter should also be looked at from the following perspectives:

• Energy density, how much of the fuel in question should be stored on the ship, and how much will it displace other cargo space and thus become more expensive than traditional fossil, very energy-dense fuels?

• What is the primary energy source of the fuel in question and how much emission losses occur when the energy changes form?

• Manufacturing technology, has a commercial manufacturing technology already been developed for the fuel, and is it under development. Can you already buy fuel somewhere?

• Legislation related to the use of fuel. Is its use permitted and safe, are there already instructions and training for the ship’s crew on the use of fuel.

• Storage on board and in port, is it possible to store fuel on board and in ports.

• Distribution logistics, whether it can be transported to the users.

• Engine technology, whether there are ships that can use that fuel and what such an engine costs compared to other options.

Technology development will change all the factors listed above and their price for the shipping company. If fuel is not yet produced, stored or distributed today, the situation may be different in a few years.

The matter is made even more complicated by international regulations that calculate emissions in different ways and punish or support different solutions. This is why various pilots and experiments are key: which fuels will become more common, and at the same time – usually – become cheaper.

How do the greenhouse gas emissions of various fuels differ?

When comparing fuel solutions, the most important long-term perspective is how much greenhouse gases its use produces – most often this is compared to the current use of heavy fuel oil. In this case, a distinction must be made between where the energy was originally produced and what form it was then transformed into so that it can be used at sea.

Fuel energy sources can be divided into two categories based on their basic energy: non-renewable and renewable energy sources. Non-renewable energy sources include coal, lignite, oil, natural gas and nuclear power. Renewables are wind, sun and biofuels.

Some of these energy sources can be used as such as marine fuel, such as oil or natural gas. Some energy sources, such as wind energy or biomass, are converted into another form instead. This second form is currently usually electricity.

Several forms of transport, such as road or rail transport, are becoming electrified at a rapid pace. However, it is difficult to store electricity for a long sea voyage, so instead hydrogen or some other chemical compound derived from it is used. Hydrogen-based fuels can be stored for a long time, hydrogen is like a more efficient battery than traditional batteries. Depending on the hydrogen energy source, different color codes are used in the discussion.

• Green hydrogen refers to hydrogen made by electrolysis from renewable energy, such as the wind or the sun. In electrolysis, water is split into hydrogen and oxygen.

• Blue hydrogen refers to hydrogen made from natural gas. In this case, carbon dioxide is released, which is recovered in the process and is not released into the atmosphere.

• Gray hydrogen means hydrogen that has been produced from natural gas, but in this case carbon dioxide has not been recovered, so it produces carbon dioxide emissions.

• Black or brown hydrogen is produced when black or brown coal is used to produce hydrogen. In this case, it produces even more carbon dioxide emissions than the use of coal, as part of the energy is lost in the process.

• Pink hydrogen is produced in a process that uses nuclear energy as a base. This is also sometimes called red or purple hydrogen.

• Turquoise hydrogen is produced in the pyrolysis of methane, where the resulting carbon is recovered.

• Yellow hydrogen refers to hydrogen produced with the help of solar energy.

• White hydrogen refers to hydrogen found directly in the soil. This is not used in practice.

Alternative fuels

A few marine alternative fuels are listed below. Traditional fossil fuels such as oil and natural gas are missing from this listing, instead we focus on so-called alternative low-emission fuels.

Electricity – electricity is one of the most potential low-emission fuels for shipping in the future. At the moment, the most common electrical solutions are shore power, i.e. the ship is in port while connected to the power grid, and it does not need to use separate auxiliary machines in the port.

Ships require considerable amount of energy, and on longer journeys and especially in ice conditions, the amount of batteries required for electricity is significant. Electricity as such is best suited for short-distance transport, such as archipelago or urban water transport. In several Nordic countries, the newest small ferries are indeed electric. On longer journeys, the number of batteries needed by the ship would reduce the cargo space too much. Various solutions have been thought of for this as well, for example using containers as batteries that can be changed in ports or using stabilization systems as batteries, but these more exotic solutions are not yet in use.

Biofuels – the easiest solution for shipping would be if current fossil fuels could be replaced directly with biodiesel or gas. Biofuels are referred to as first and second generation biofuels. First-generation fuels are made from, for example, food waste, and second-generation fuels are made directly from, for example, trees grown for that purpose.

Unfortunately, production of biofuels is significantly less than consumption. It is assumed that those forms of transport, such as air transport, where the energy density of the fuel is important, will use most of the future biofuels. Then there would not be enough of it for maritime use. However, it is clear that biofuels will play a big role in the maritime transport of the future.

Hydrogen – the problem with using hydrogen is its low energy density, even when liquefied, hydrogen requires more than three times more space than heavy fuel oil to produce the same amount of energy. Because of this, pure hydrogen is no longer often seen as a potential fuel, but instead people think about converting hydrogen into ammonia, methane or methanol, which have more energy in a smaller space. This change can happen either by using electricity or biological fuels. Unfortunately, some energy is also always lost in this change, so every hydrogen-based fuel is inevitably a slightly worse solution – on the other hand, it solves the hydrogen space problem.

Ammonia – when liquefied, is already significantly better in terms of energy density than hydrogen, so it does not need as much space on the ship. On the other hand, the liquid tank itself requires a lot of space on board. However, the problem with ammonia is its toxicity, which places slightly more demands on it as a fuel.

Methane, LNG, biogas – LNG, liquefied natural gas, is already a commonly used fuel in shipping, especially because it contains no sulfur at all, so no sulfur scrubbers are needed for its use. However, it produces almost the same amount of carbon dioxide a than heavy fuel oil, and in addition, low-pressure engines also release pure methane, a greenhouse gas even more significant than carbon dioxide, into the air. Methane can also be produced from hydrogen by adding carbon.

Methanol, ethanol – are other liquids where hydrogen has been converted into an energy form with a higher density, thus requiring less storage capacity than hydrogen.

Nuclear power – has served as a shipping fuel for decades, for example in the ice-breaking of Russia’s Arctic regions. So-called small reactors are now being worked on as an alternative fuel, but there are many risks associated with nuclear power, and it is still uncertain whether commercial solutions that can be used in general can be obtained with the help of nuclear power.

How do shipping companies prepare for new fuels?

Several different fuels have been presented above, and as we can see, the fuel itself does not tell about greenhouse gas emissions, but you have to look at how the fuel was produced. Although most of the new hydrogen-based fuels are not yet based on a renewable energy source, these other-colored hydrogen-based fuels allow ships to be built ready for the new technology, and then when the green fuel is available, it can be switched to.

Here, however, it must be remembered that the mere availability of fuel is not enough, but distribution, storage, etc. are needed, so the entire transport sector and the state participate in this change.

Electricity is the most likely solution for short trips, but different hydrogen-based fuels are planned for longer trips. Currently, ships are often built with engines that can use several fuels. In this way, shipping companies are also prepared for various developments in the future, and can use cheaper or better available fuel if necessary.

In electric hybrid solutions, the ship uses electricity in addition to its actual fuel (either from land, batteries or fuel). This makes the use of the engine more efficient, optimizes energy consumption, and in certain situations (e.g. in the harbor or on the harbor fairway) it is possible to travel on electricity alone.

Multi-fuel engines usually use fossil liquid fuel, but they can also use gas LNG or alternatively other liquids such as hydrogen or its derivatives.

It is still too early to say which of these fuels will be successful. Price is only one factor in this ever-evolving and changing puzzle. However, it is clear that the most important thing for shipping companies and ports is to monitor the development and take all these perspectives into account in their investments. The current war in Ukraine has only accelerated shipping’s shift away from fossil fuels towards low-emission fuels while raising the prices of traditional fossil fuels.

This article was published in NavigatorMagazine in Finnish 26.9.2022.

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