Global shipping sets course for new nuclear

The maritime industry is looking closely at nuclear power to replace heavy fuel oil as advances in small modular reactor (SMRs) designs move toward demonstration.

An illustration of a nuclear-reactor-fitted ship (Source: American Bureau of Shipping)

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Generation IV nuclear reactors, including SMRs, come with many promises over their larger predecessors, including a smaller footprint, inherently safe designs, finance-friendly project sizes, and cookie-cutter manufacturing.

These new designs, coupled with global decarbonization drives - the International Maritime Organization (IMO) wishes to reduce total annual greenhouse emissions from the industry by up to 30% by the end of the decade versus 2008 – has led many to believe that the time has come to take nuclear out on the open seas.

“Marine owners and operators are saying … we need to consider all the other options to reach zero, and that's when they raise the flag and say, tell us more about nuclear power and how we can solve this problem,” says American Bureau of Shipping (ABS) Senior Engineer and Nuclear Programs Lead Meg Dowling.  

The potential benefits of nuclear-propelled ships could be transformational for the industry, according to a study by the Herbert Engineering Corp. (HEC) commissioned by the ABS.

The study modeled the impact of two, lead-cooled 30 MW fast reactors on a 14k TEU (capable of holding around 14,000 standard 20-foot containers) container vessel and four, 5MW, heat-pipe microreactors on a 157k DWT (with roughly 157,000 metric tons of carrying capacity) Suezmax Tanker.

Both concept vessels would emit zero carbon dioxide making them an attractive option for an industry that currently churns out around 2% of global energy-related carbon dioxide, according to the International Energy Agency (IEA).

On the container carrier, the addition of a nuclear reactor would increase cargo capacity and operational speed while eliminating the need for refueling during its entire 25-year lifespan, the study found.

The reactor on the Suezmax vessel, meanwhile, would also raise operational speeds and would only need refueling once in its lifespan, but would decrease cargo capacity.

Number of ongoing SMR projects by country and status

(Click to enlarge)

Source: IEA analysis based on own research and data from International Atomic Energy Agency (IAEA)


The study is a high level, conceptual look at nuclear power and its potential for shipping, the ABS says.

Direct comparisons with other alternative fuels, such as clean hydrogen, ammonia, and methanol, are yet to be looked at and may be the subject of future studies, says Dowling.

However, cost comparisons can be difficult between alternative fuels.

On the one hand, refueling and bunkering can be expensive. Nuclear options can avoid both those factors.

On the other hand, new nuclear is still to be fully demonstrated and is likely, at least before Gen IV reactors reach nth-of-a-kind iterations, to be costly.

Meanwhile, cost estimates both for new nuclear and full-scale clean hydrogen applications are based on unproven assumptions, making an apples-to-apples comparison very difficult.

Also, the cost of each individual technology and fuel are only part of the picture.

“The only real comparison that's useful to us is the levelized cost of ownership, the one-time future costs of CapEx plus the Opex, because if you only compare operational expenses of a nuclear ship and a conventional, or some other alternatively fueled, ship they're going to look very different,” says ABS’s Dowling.

“You have to consider the entire cost of ownership over the lifetime, and that includes decommissioning.”

Potential alternative

Civil nuclear solutions were found to have the potential to be a reliable and cost-effective alternative to other marine fuel options, according to another study, which looked at different reactor technologies and nuclear fuels.

Conducted by nuclear energy development and consultancy company ULC-Energy for global mining company and major shipping charterer, BHP, the study examined fast spectrum, high temperature gas reactors, and molten salt reactors, as well as different nuclear fuels, moderators, and coolants, and how they would map against civil maritime shipping applications.

Moving the industry away from heavy fuel oils, which are cheap and abundant but also heavily polluting, is one of the main challenges, says Director of Consulting at ULC-Energy Michael Hewitt.

“The shipping industry has had this wonderful fuel for years that not only is energy dense, abundant, cheap, safe and reliable in operation, but nobody else really wants it so the industry doesn't compete with anybody else for it,” says Hewitt.

Nuclear offers longer refueling intervals, higher power, and faster speeds while ULC-Energy anticipates alternatives, such as synthetic fuels from clean hydrogen, can initially be expected to be directed at the highest value markets, such as the chemical industry and aviation and long-distance trucking, before they are available at scale for the shipping industry.

Also, unlike other mobility sectors, maritime offers large vessels that can easily accommodate bulky and heavy equipment, such as an on-board nuclear energy system, Hewitt says.

Hewitt believes that nuclear power’s time has come as a carbon-free, baseload provider, especially as the public grows to understand the limitations of intermittent power from renewables.

While there are several areas of the shipping industry’s current operations that need to be assessed to be able to accommodate the reality of nuclear power, it is public opinion and surrounding regulation that pose the largest challenge, he says.

“Stakeholders need to feel that the ship that's coming into port is subject to a high quality and trustworthy regulatory regime, a crew that has been properly educated and trained, that they've been adequately certified, and that all the correct procedures are in place. That's how you're going to get people to feel comfortable with it,” Hewitt says.

By Paul Day