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The Case for Nuclear Cargo Ships
https://spectrum.ieee.org/nuclear-powered-cargo-ship [ieee.org]
The shipping industry has been trying to cut its carbon emissions for years, and with little to show for it. Nearly all of the world’s ship fleet still runs on diesel fuel, with about a quarter of new ships on order being built to run on somewhat lower-carbon alternatives like liquefied natural gas, methanol, or hybrid propulsion.
The industry now faces serious pressure to pick up the pace. Shipping uses over 300 million tonnes of fossil fuels every year, producing 3 percent of greenhouse gas emissions. At a July meeting of the International Maritime Organization, the U.N. body that governs the industry, representatives doubled down on carbon-reduction ambitions, setting a net-zero emissions goal for 2050. The IMO’s previous goal was a 50 percent reduction by 2050 in comparison with 2008 levels. The European Union plans to begin charging shippers for carbon emissions this year.
Hedging its bets, the industry is exploring ammonia, batteries, and hydrogen, among other options for powering ships. A small but growing group of analysts, though, are pushing for a zero-emissions technology that already plows the oceans: nuclear propulsion.
Today, some 200 nuclear reactors are already operating on 160 vessels, mostly naval ships and submarines. Nuclear-powered ships can go years without refueling. They do not need giant fuel tanks, which opens up more space for cargo and passengers. And the reactors themselves are getting better, too: Fourth-generation small modular reactors (SMRs) being developed by companies including U.S.-based TerraPower and London-based Newcleo should be safer and simpler to operate than conventional reactors.
For shipping, nuclear is really the only abundant, realistic, carbon-free option, according to Håvard Lien, vice president of research and innovation at the Norwegian shipbuilding company Vard Group. “It’s becoming more and more apparent that we need to do something about emissions,” he notes. “At the same time, it’s becoming apparent that alternative-fuel solutions we’re looking at have big drawbacks, and that producing these fuels will take a lot of green power that will be needed to replace coal and gas on shore. Having an energy source that you can fit onboard a ship and does not compete with shore energy is a very high priority.”
Vard Group is part of NuProShip, a consortium of the Norwegian maritime authority, universities, shipbuilders, and shipping companies that aims to develop a Generation IV reactor for marine vessels. The group has shortlisted three designs and plan to have picked one by the end of 2024.
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Now, the immense scale of shipping’s decarbonization challenge, along with new reactor technologies, are prompting a reevaluation of nuclear merchant ships. In fact, for commercial shippers, there aren’t any realistic alternatives to nuclear, says Jan Emblemsvåg, professor of ocean operations and civil engineering at the Norwegian University of Science and Technology. “Engines in ordinary ships are the size of houses,” says Emblemsvåg, who is leading NuProShip. And a great deal of space is taken up by fuel: “A container vessel going from Amsterdam to Shanghai requires roughly 4,000 tonnes of fuel.”
An SMR would be much more compact and lightweight. According to Emblemsvåg, a molten-salt reactor—which uses a mixture of thorium and hot liquid salts as both fuel and coolant—would also save about $70 million over the lifetime of a ship, compared with a similar vessel powered by engines that burn diesel fuel (or, more precisely, heavy fuel oil). Another plus for nuclear-propelled ships is easy access to an endless supply of cooling water.
