Nuclear-powered novelties

Trials and research programmes continue to determine the part this fossil-free source of power will conduct in the drive to net zero.

As the energy industry transitions for a net zero future, the decarbonisation of the maritime sector is a major subject of discussion. Maritime vessels have typically used fossil fuels, however, methods for clean energy such as nuclear propulsion are now looking more viable in commercial vessels such as shipping and fishing.  

Nuclear marine propulsion involves the propulsion of a ship or submarine with heat generated by a nuclear reactor, that creates steam for a turbine to turn the ship’s propeller through a gearbox, or an electric generator and motor. Nuclear propulsion was usually reserved for navies, but now, new developments show potential for increased use in commercial shipping and fishing.  

Nuclear novelties in Scandinavia 

Stella Polaris and Norway’s Institute for Energy Technology (IFE) are considering putting a uranium-powered microreactor on board a shrimp trawler. Biofuels like hydrogen, ammonia or methanol may have been the first choices, being zero-emission gases, but shrimp trawlers have such high fuel requirements there would not be enough storage space on board.  

Copenhagen-based Seaborg Technologies is planning to put compact molten-salt reactors (MSRs) on a power barge that will support the grid and renewables. Molten-salt reactors are smaller and lighter than standard reactors, operating at close-to-normal atmospheric pressures. Molten salt nuclear power is also attracting attention and investment in Southeast Asia, with Bureau Veritas and ThorCon recently agreeing to develop a 500 MW molten salt nuclear power barge in Indonesia. 

In Norway, shipbuilder Ulstein launched its design to generate zero-emission power for expedition cruise ships in remote regions, with research facilities onboard also. Thor will use MSRs, dissolving thorium in liquid salt, to create a reaction that heats the salt and produces steam to drive an electricity-generating turbine. To reduce maintenance needs, Thor will not need to be refuelled, only requiring salt to be removed from the reactor every 3 to 7 years. This negates a need for regular stops, bunkering or operational windows. Also, waste is minimised since the salt is reprocessed and can be re-used. 

Could thorium lead the way in the decarbonisation of commercial maritime? Robert McDonald, Principal Engineer at Norway's Institute for Energy Technology (IFE) says it’s not quite so simple: “The use of thorium is a topic that comes up often, and the basis is very good because of its properties. The major problem is there is no mature supply chain for thorium. This would have to be solved first. Until the supply chain is established, uranium will still be the major fuel source for nuclear power.” 

Thor will use MSRs, dissolving thorium in liquid salt, to create a reaction that heats the salt and produces steam to drive an electricity-generating turbine (Credit: Ulstein)

Safety questions 

Even if nuclear meets the needs of commercial vessels while reducing emissions, there will need to be a thorough understanding of the safety of bringing nuclear reactors on board. Hurdles to face involve regulations, design, and research for safety and sustainability. Robert McDonald speculates that for nuclear energy “the key will be to start the research to prove it can be operated safely in the commercial industry by looking at all possible situations and see what is realistic.”  

Last year, the US Department of Energy awarded the American Bureau of Shipping (ABS) a contract to research the challenges of adopting new reactor technology in commercial maritime applications. ABS will develop models of different advanced reactor technologies and form an industry advisory on the commercial use of modern nuclear power. 

Although nuclear may support a greener maritime future, and the technology could be safe to bring on board, understanding and acceptance will need to be gained over time, which is why it is important to continue the conversation. 

Clarissa Wright is a freelance science journalist and Editor of NatureVolve