As the global ocean shipping industry looks for the best ways to decarbonize and reach zero net emissions, it’s seeking new sustainable energy sources.
A new study by A.P. Moller-Maersk and Lloyd’s Register confirmed that, based on market projections, the best-positioned fuels for research and development into net zero fuels for shipping are alcohol, biomethane and ammonia. Shipping is responsible for 2 percent to 3 percent of global greenhouse gas (GHG) emissions, so the industry has significant potential to help create a carbon-neutral economy by 2050, the study emphasized.
Maersk, considered the largest ocean cargo carrier, said energy efficiency has been and still is an important tool for the company to reduce CO2 emissions and that efficiency measures already implemented have positioned it 10 percent ahead of the industry average. But getting to net zero requires a total shift in the way deep sea vessels are propelled, the company noted. That’s why the shipping industry needs to introduce carbon-neutral propulsion fuels and new technologies.
“The main challenge is not at sea, but on land,” Søren Toft, Maersk chief operating officer, said. “Technology changes inside the vessels are minor when compared to the massive innovative solutions and fuel transformation that must be found to produce and distribute sustainable energy sources on a global scale. We need to have a commercially viable carbon-neutral vessel in service 11 years from now.”
These three fuel pathways have relatively similar cost projections, the study said, but present different challenges and opportunities.
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“It is too early to rule anything out completely, but we are confident that these three are the right places to start,” Toft said. “Consequently, we will spend 80 percent of our focus on this working hypothesis and will keep the remaining 20 percent to look at other options.”
The study explained that alcohols such as ethanol and methanol are not highly toxic liquids, with various possible production methods–directly from biomass and/or via renewable hydrogen combined with carbon from either biomass or carbon capture. Existing solutions for handling the low flash point and for burning alcohols are also well established. In addition, ethanol and methanol are fully mixable in the vessel’s bunker tanks, creating bunkering flexibility.
However, the transition of the industry toward alcohol-based solutions is yet to be defined. On the other hand, biomethane has a potentially smooth transition given existing technology and infrastructure, according to the study. But the challenge is something called “methane slip,” which is the emission of unburned methane along the entire supply chain.
As for ammonia, it is carbon free and can be produced from renewable electricity, the study noted. The energy conversion rate of this system is higher than that of biomaterial-based systems, but the production pathway cannot tap into potential energy sources such as waste biomass.
The main challenge for ammonia is that it is highly toxic and even small accidents can create major risks to the crew and the environment, the study warned. This makes the transition from current to future applications a huge challenge for ammonia.
“The next decade requires industry collaboration, as shipping considers its decarbonization options and looks closely at the potential of fuels like alcohol, biomethane and ammonia,” Lloyds Register CEO Alastair Marsh said. “This joint modelling exercise between Lloyd’s Register and Maersk indicates that shipowners must invest for fuel flexibility, and it is also clear that this transition presents more of an operating expenditure rather than capital expenditure challenge.”
According to Maersk and Lloyds Register, batteries and fuel cells are unlikely to have an immediate role in propelling commercially viable carbon-neutral deep-sea vessels.