Nuclear or bust: does the atom hold the secret for net-zero shipping?

“But if you take into consideration the energy intensity or the electricity needed to produce these [low- and zero-carbon] fuels, it is as much as what the EU consumes in a year,” he says, adding these green fuels will also come with high costs.

Shipmanager OSM Thome is involved in three projects — including one with Dr Emblemsvåg — exploring the development of nuclear power in commercial shipping. Recent advances in the size and technology of power plants make them far different than the pressurised water reactors that were used in those earlier ships, he says.

“What we are looking at in our projects are Generation 4 reactors, which employ gas-cooled, molten salt-cooled and lead-cooled technology,” notes Mr Lie.

“Every single piece of nuclear fuel waste is accounted for”

Advances in nuclear power over the last five years make it an intriguing technology to explore for maritime applications because of its potential to provide large amounts of zero-emissions energy. And while nuclear power has been used in naval propulsion applications for decades, questions and concerns about its broader application in commercial ships must be addressed.

Three myths about nuclear energy

ABS senior engineer, Meg Dowling, addressed the safety of nuclear energy, which she describes as one of a series of three myths about the technology: “The truth is that nuclear power is as safe or safer than any other form of energy available that we’ve used. It is one of the safest forms of energy available to us.” The comparison is particularly striking when considering the “incalculable number of injuries, harmful emissions and deaths due to greenhouse gases and the harmful gaseous emissions that are unaccounted from the other energy sources,” she says.

“Can a shipowner own a reactor?”

A second myth Ms Dowling highlights is that there is no solution to managing nuclear waste. “It’s one of the most highly managed and controlled materials on the planet. Every single piece of nuclear fuel waste is accounted for.” Long-term solutions are not a matter of technology but policy, she notes. And nuclear energy produces a “much lower volume than the waste that we were seeing from other forms of hydrocarbon fuels, and their alternatives.”

The third myth is that nuclear power plants expose the public to radiation. “We are all exposed to naturally occurring radiation, whether from space, the Earth or materials that surround us. In the US, the total radiation exposure per person is the equivalent of eating one banana per year.

“We have ways of measuring, limiting and shielding ourselves from harmful levels of radiation at a very conservative level, and it’s not a concern for advanced nuclear reactors.”

Ms Dowling says advanced small modular and micro-sized reactors are being explored for commercial marine applications. She says the size of these reactors “are a natural fit” for large commercial ships. She defined small modular reactors (SMRs) as between 10 and 300 MW capacity and micro reactors between 10 and 20 MW. These size units would also be well suited for port electrification or floating offshore power plants.

“But it is more than just a technical problem,” she says. To prove its feasibility on a global commercial marine scale, the industry must also address the regulatory and economic hurdles. IMO is set to revisit SOLAS Chapter VIII, which is the code covering the safety of nuclear merchant ships. The code has not been updated since 1981, and only considers the use of pressurised water reactors and not current Generation 4 reactor technologies.

London-based World Nuclear Transport Institute is working on a gap analysis to support the update of the code, which it plans to present to IMO before the end of 2024.

Nuclear reactor ownership

Because nuclear energy is so tightly regulated, scaling up nuclear-powered commercial shipping will require new business models. “Who can own a reactor? Can a shipowner own the reactor?” asks Mr Lie.

“We may need to have interesting arrangements for liability, insurance and those kinds of levels of ownership,” says Ms Dowling. “But we also need to think very critically about the crew and the training required for merchant nuclear applications. If we do not prove its economic feasibility, it will not be implemented.”

But there does seem to be an economic case for SMRs. Based on his research, Dr Emblemsvåg says a molten salt modular reactor could outcompete a 15 MWh, two-stroke engine operating on HFO. “Assuming 30 years and 6.5% weighted average cost of capital, you will see that the molten salt reactor can actually out compete the heavy fuel oil straight on cost,” he says.

He cited three advanced nuclear technologies that would prove economically viable if matched with the right size ship: helium gas-cooled reactors (5-20 MWe) for small ships, molten salt units (25-50 MWe) for medium-sized ships and liquid lead (50+ MWe) for the largest vessels.

“From a technological point of view, it is not a problem. Even economically I think this is very doable. This will boil down to two major things: regulations/politics, and insurance. If we can solve these two non-technical issues, I think this can be very doable,” concludes Dr Emblemsvåg.

Through its NuProShip research project, NTNU and the Norwegian Government are aiming to have an existing steam-powered ship converted and fully operating on nuclear power in 2030.

And the clock is ticking to add nuclear to the alternative fuel mix if shipping is to meet its net zero ambitions. “We need to see these nuclear-powered ships or floating nuclear power plants implemented from 2030 onwards,” says Ms Dowling. “If we start in 2040, it will be too late to get to scale up on time. She emphasises that the industry needs to get these demonstration projects successfully up and running within the next five years.

This article is based on remarks made by Dr Emblemsvåg, Ms Dowling and Mr Lie during a webinar, Nuclear-powered commercial vessels: overcoming challenges and seizing opportunities, produced by Riviera and sponsored by Marine Propulsion.