top of page
  • Writer's pictureSarah Whiteford

Is hydrogen the next fuel in shipping?

Updated: Aug 13, 2021

“This is the fourth energy revolution in shipping — from rowing our boats to sails to steam engine to diesel engine and we have to change it once more,” said Alex Saverys, CMB chief executive and scion of one of Belgium’s oldest shipping families” (Financial Times). As the shipping industry works to cut their emissions and many companies like bp and Maersk work to become net zero by 2050, we hear a lot about alternative fuels. Hydrogen is one of the most promising alternatives to traditional bunker fuel. It can be used as a fuel or in fuel cells and new ships are already being ordered with the ability to run or easily convert to running hydrogen fuel. But why do we need alternative fuels? According to Financial Times, shipping accounts for about 3% of global emissions, moving people and products around the world. Carbon emissions from shipping are projected to increase from now until 2050, making alternative fuels a necessity, as well the ability to use these fuels with minimal retrofits.

Carbon emissions are set to increase between now and 2050. Image from Financial Times.

So what is hydrogen fuel and why is it leading the pack of alternative fuels in the race to net zero?

With the goal being net zero emissions, we need fuels that don’t emit greenhouse gases or harmful chemicals into the air. “IMO 2020”, the International Maritime Organization’s new rule on sulphur in fuel went into effect in 2020, limiting the sulphur content of fuel to 0.5% from 3.5% prior. This caused a switch from heavy fuel oil to very low sulphur fuel oil (VLSFO) - reducing sulphur dioxide emissions by an estimated 77% - but sulphur is only a part of the equation. Traditional shipping fuels can emit CO2, particulates, NOX, and other byproducts. In contrast, hydrogen releases water, a mixture of hydrogen and oxygen when burned, helping it to fit the mold of an ideal fuel.

How does hydrogen production work?

While hydrogen is the most abundant element in the universe, it’s uncommon to find it in its pure form of H2 here on Earth. It bonds readily with oxygen to make water (H20) and carbon to make molecules like methane (CH4). As William Alan Reinsch says in his article at CSIS, most pure hydrogen gas made currently is created in a carbon-intensive process from sources like methane. The article cites that “The production of hydrogen emits 830 million metric tons of CO2 globally each year, more than the total CO2 emissions of Germany in 2017.” Low or no-carbon hydrogen will likely be produced using electrolysis with water, which has almost no emissions.

Hydrogen production methods. Image from

Currently, hydrogen production is divided into three categories based on the carbon intensity: gray, blue, and green. 95% of annual hydrogen production is gray hydrogen, produced using fossil fuels, much of that from methane. The process is called steam reforming. “Gray hydrogen yields approximately 10kg CO2 per kg H2 produced, placing its carbon footprint between that of natural gas and coal.” Blue hydrogen is produced with the same process as gray hydrogen, but carbon capture and storage (CCUS) technology is used to capture 50-90% of the CO2, leaving it with 2-5 kg CO2 per kg H2 produced.

Green hydrogen is produced from electrolysis, splitting the hydrogen and oxygen in water. When renewable energy is used to power the electrolysis, green hydrogen is produced without CO2 emissions at all. It is still listed as less than 5% of the emissions of gray hydrogen, since electricity generation and transportation still have emissions. Although the process has been used for 100 years, it is more expensive to produce than either gray or blue hydrogen. For transport, it needs to be compressed and cooled, or stored as another molecule rather than H2.

What are the advantages of hydrogen?

There is already a market in place with producers starting to scale up for clean energy demands. Hydrogen can also be stored for long periods of time in large amounts, which is great for transportation and shipping. Most ships can be retrofitted with fuel cells for hydrogen, which is loaded into the cells. The electrolysis process used to create green hydrogen is reversed, creating electricity and heat to power ship’s systems. According to Reinsch, efficiencies of 60% to 80% are possible with this setup and the fuel cells have no moving parts. Having a fuel that requires minimal cost to retrofit is important, and vessels are already in production that can run on current fuels as well as hydrogen with minimal modifications.

“The Hydroville’s drivetrain operates via hydrogen (Credit: CMB)”. Image from BBC.

What are the disadvantages of hydrogen?

According to the CCIS interview, “Hydrogen is extremely flammable and has a larger ignition range than other traditional fuels, meaning that hydrogen will burn at both low and high concentrations when combined with oxygen. However, there are safety measures that can mitigate this risk during storage, transportation, and ignition.”

Additionally, size and temperature of storage required for liquid hydrogen can be an issue. According to BBC, “the real challenge for using it in long-distance shipping is how tricky it is to store. Hydrogen cannot simply replace bunkering fuel in the current system. To store it on board a ship as a liquid, it needs to be frozen using cryogenic temperatures of -253C (-423F), says Hubatova.” According to ResearchGate and, heavy fuel oil has an energy density of 40 Mj/kg while hydrogen has an energy density of 120 Mj/kg. Pound for pound (or kilogram for kilogram), hydrogen has three times the energy density of HFO, making it a great alternative, except for its volume. HFO has a Mj/L of 38, while hydrogen has a Mj/L of 8 Mj/L, meaning more than 4 times the amount of hydrogen is needed by volume to equal HFO. So while the fuel is lighter, it takes up more room, meaning ships would need some modifications. In CCIS it is stated that studies show 99% of voyages between the US and China could be powered by hydrogen with small changes like reducing cargo by 5% to make room for fuel. 43% of those voyages could be made with hydrogen power with no changes.

Cost is another hurdle, with the same interview above stating that gray hydrogen is around $1-2/kg, blue hydrogen is 30-80% more expensive, while green hydrogen is about 4 times the price. Many factors will likely decrease these costs over time, such as cheaper renewable energy, reduction in electrolysis costs, and government intervention. Government support will help to make the change over to green hydrogen easier and bring the cost in line with what shipping companies can pay. According to CCIS, this will need to come quickly as some countries like Norway are already putting in place much stricter regulations on emissions: “all cruise ships and ferries sailing through Norway’s fjords must be emissions-free by 2026”. William Alan Reinsch at CCIS also has some ideas on how to make this transition easier from a policy perspective in the United States:

  • “Strengthen the domestic hydrogen industry to build a manufacturing base for and lower the cost of low-carbon hydrogen...

  • Collaborate among industries to encourage hydrogen production throughout the U.S. economy...

  • Stimulate commercial demand for low-carbon hydrogen by strengthening regulations on shipping emissions and providing tax incentives for shipping firms to retrofit their ships with hydrogen fuel cells...

  • Partner with like-minded parties like the European Union in order to harmonize international standards for shipping emissions and hydrogen fuel...”

“An experimental hydrogen boat from France’s Energy Observer tests types of renewable energy (Credit: Peter Kovalev/Getty Images)”. Image from BBC.

What about alternatives?

  • There are many alternatives in the renewable fuel category, including some old ones. Wind propulsion is making a comeback, with new technology allowing for some vessels to make journeys on wind power alone. The main drawbacks are that wind is unpredictable and even the largest offshore turbine doesn’t have enough output to power a containership.

  • Solar is another option, but works better as an assisting power source along with other propulsion methods. New solar technology is being developed that could change this in the future, especially in sunny areas where a lot of solar energy could be gathered.

  • E-methanol is another contender that is water soluble, stores at room temperature, and doesn’t take much energy to produce, but it does come with emissions and less energy per volume than traditional fossil fuels.

  • Biofuels are another option, but aren’t yet mature enough.

  • Electricity is becoming more popular with passenger vehicles, but storage to power larger vessels is an issue that has yet to be solved. New battery technology like iron air batteries and others may provide more usefulness to electricity for large ships.

Check out 10 promising alternative shipping fuels for more information on other fuels.

“One report found shipping could almost completely decarbonise by 2035 using currently known technologies, including hydrogen (Credit: CMB)”. Image from BBC.

How does hydrogen burn?

According to BBC, hydrogen can be used in a few different ways to make power. It can be burned in an internal combustion engine like a traditional fuel, but this can create nitrogen oxides, pollutants that can be captured after. Fuel cells chemically convert hydrogen into electricity with water as the emission. The main issue with fuel cells is the area needed - more space is required due to hydrogen’s low energy density per liter. Steamology, a company in the UK, is developing steam-powered hydrogen electricity. The process produces no emissions, but the hydrogen has to be burned in the process. Fuel cells are the cleanest method, while burning hydrogen and capturing emissions is also an option.

The Good News

The good news is that according to BBC, the International Transport Forum published a report that it is possible for the shipping industry to almost totally decarbonize by 2035 with current technology. This means that the goal of complete net zero by 2050 should be well within reach even without expected advances in tech. As of now, hydrogen is leading the way with a host of other alternative fuels, and we are excited to see the new technology that decarbonizes shipping for good!

We plan to cover more alternative fuels and the vessels powered by them in future articles, so keep an eye out for those.

Happy Friday!


Recent Posts

See All


bottom of page