Marine transportation is an important transportation industry sector, rivaling aviation in size, and it’s a significant carbon emitter. Three percent of carbon emissions come from the maritime industry. The ship categories producing most of the emissions are bulk carriers, tankers, and container ships. The industry faces an imperative need for decarbonization. The current trajectory leads to a 20% increase in emissions. While shipping is a carbon-efficient mode of transport, it currently doesn’t get a pass and must do its part in reducing man-made emissions.

To be in line with the well-known scenarios of the International Energy Agency, the so-called well-below-two-degrees warming scenario, or 1.5-degree warming, significant decarbonization would be necessary, and it hasn’t happened yet.

Maritime Transport Lags in Decarbonization

The marine sector lags behind others — notably road and aviation. There are many reasons, but the main one is that renewing ships and ship engines, which can burn only a certain type of fuel, is a major and costly decision. Ships are on the water for at least 20 years, often more. Owners are eyeing solutions but find it difficult to choose. There is a tendency in the industry for a wait-and-see approach.

The trigger for change will be regulations. The cost of fuel is 25% to 40% of the cost of operating a ship. Changing to a different fuel, which might be 50% more expensive, won’t happen voluntarily. Shipping is an international business, and you’d expect the International Maritime Organization to take the lead on legislating a framework for decarbonizing marine fuels globally. It is happening, but it’s taking a long time.

Meanwhile, Europe proposed the Fuels EU Maritime Initiative in July 2021. It’s part of a package of proposals called Fit for 55, designed to reduce emissions by 55%. Between 2030 and 2050, there will be a sea change in the use of energy carriers, away from fossil fuels and toward decarbonization. Different types of fuels, which may have the same energy content, will provide significantly different results in greenhouse gas reductions and carbon intensity. By selecting a carbon intensity target, regulators want to reward fuels and energy carriers that reduce emissions rather than simply reward the renewable fuel content, regardless of greenhouse gas reductions. The trajectory is a 2% reduction by 2025, 6% by 2030, and 75% by 2050.

Another influence is corporations, including Amazon, Ikea, and Unilever, that have pledged to use only zero-carbon fuel by 2050. When you have big corporations making commitments to decarbonize, it has an impact on their whole supply chain, including shipping.

What Makes a Good Marine Fuel?

There are features to what makes a low-carbon marine fuel, and a handful that stand out are:

• Cost
• Energy density
• Sustainability
• Low-carbon intensity
• Safety
• Reliability
• Ease of use
• Compatibility with current fleet and infrastructure

Biofuels and eFuels, synthetic fuels from green hydrogen and captured carbon, make good marine fuels. You have natural gas and biomethane in the form of liquified natural gas (LNG) or bio-LNG, if the methane comes from biogenic feedstock. Feedstock is any biological material used as fuel or converted to a fuel or energy product.

Biomethane/LNG is already proven. Ship owners are converting to LNG or buying new LNG vessels. Biomethane is easy to produce and cheap. It’s clean burning and compatible with fossil natural gas. People equipping ships with LNG engines know they’ll never run out of fuel. Energy density isn’t great, compared with the incumbent marine gasoil and fuel oil. To keep LNG in liquid form, it needs to be cooled to a low temperature, requiring bulky cryogenic equipment. Then there’s the cost and time to convert the fleet. Another problem with biomethane is the risk of leakage. Methane is 30 times more potent than carbon dioxide. A small quantity of methane leaked into the atmosphere can have a major impact.

Bio-methanol is already used commercially as a marine fuel. For example, Mærsk has invested a significant amount in methanol ships. One advantage is the number of ways to produce bio-methanol: for example, from biogenic feedstocks, by gasification and reforming the syngas into methanol. You can also produce methanol from green or blue hydrogen with carbon capture. And, of course, there is fossil, or gray, methanol. You’ll never run out of fuel, and it’s clean burning. Energy density is a drawback, as is cost and time to convert.

Hydrogen and ammonia are grouped together because ammonia converts hydrogen energy into something easier to transport as a liquid. Green hydrogen, from the electrolysis of water with green electricity, could be a long-term solution. It has high sustainability credentials, there’s no use of land, it’s clean burning, and there’s no competition for feedstock. However, hydrogen is a long way from being commercially available. A key problem is the high cost of electrolyzers and green electricity. Converting hydrogen to ammonia improves energy density, but it still doesn’t compare favorably with current fossil fuel. Most importantly, handling and safety are an issue: ammonia is highly toxic.

Ultimately, biofuels are the most available and easiest to integrate. Using biofuels delays risky decisions and helps shipping organizations start decarbonization. Both renewable diesel and biodiesel — also called fatty acid methyl ester (FAME) — have been tested extensively to replace fossil marine gasoil, but the price is higher than the incumbent fuel.

In the case of FAME, and renewable diesel using HVO, another drawback is feedstock limitations. The feedstock are lipids: fats and oils. Regulators are curbing the use of food crops, such as palm oil, rapeseed oil, and soybean, and pushing the development of waste oils, such as used cooking oil. However, these are finite resources. Simply put, the world will run out of eligible lipids for biofuels for FAME and HVO.

One way to avoid that is to switch to eFuels, which may be the long-term solution. However, the cost is currently prohibitive, and production capacity is small. But as a long-term marine application, eFuels in the form of fully compatible e-hydrocarbons looking like a diesel or a very clean fuel oil would have an advantage over the simple use of ammonia as a carrier for hydrogen energy.

There are additional possibilities, such as something that would be lower quality than HVO renewable diesel but good enough for marine engines. We might well be describing bio-methanol, but other solutions are coming from some of the thermochemical conversion processes that are being developed to process other feedstocks beyond lipid — such as biomass, municipal solid wastes, recycled carbon, and recycled plastics. What about techniques such as pyrolysis, hydrothermal liquefaction? Could some of the byproducts of these processes be the perfect marine biofuel?

As an example, Mærsk and Vertoro are developing biofuels made from lignin. Lignin is a part of biomass that is difficult to process; in fact, it is the most difficult part from which to get useful products. In other developments, U.K.-based Green Fuels Research recently did a pilot producing a marine biofuel from salmon farming waste. These experiments and others could be a game changer if successful.

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About Olivier Macé

Olivier Macé is owner and Principal at Broadmanor Consulting, a biofuels consultancy. Previously, he worked in the downstream oil and biofuels sectors for 31 years, holding various roles in refining, trading, supply and logistics, fuels, and lubricants sales, as well as renewable energy. Olivier joined BP Biofuels at its inception and held various leadership positions, including Regional Director, Europe and Africa and Global Head of Strategy, Regulatory Affairs and Communication. Olivier was Biofuels Director, Europe Fuels at BP, responsible for the biofuel’s commercial performance in the entire region.

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This energy industry article was adapted from the GLG Webcast“Low Carbon Fuels in the Maritime Industry.” If you would like access to events like this or would like to speak with energy industry experts like Olivier Macé or any of our approximately 1 million industry experts, please contact us.