Nuclear offers solution to maritime contamination

Nuclear energy can be used to power the world’s shipping industry, which already produces more greenhouse gases than the global aviation sector and is expanding, directly through nuclear propulsion or indirectly through hydrogen and ammonia production, experts say.

An artist rendition of the 'The Earth 300 Vessel', a proposed nuclear-powered research vessel (Source: Earth 300)

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The international shipping industry churns out almost 3% of the world’s carbon dioxide emissions, a figure that could as much as triple by 2050 under a business-as-usual scenario, warns the International Maritime Organization (IMO), which is pushing it to modernize and cut emissions by at least half, compared to 2008, by 2050.

Improved engine designs will help curb contamination, but a radical overhaul is necessary if net zero is to be reached, say researchers.

“Efficiency gains will help, but such improvements cannot reduce emissions to zero by themselves, let alone offset additional emissions from increased shipping activity. The bottom line is that the maritime sector needs to decarbonize and is under pressure from global organizations and consumers to do so,” says the introduction to a white paper on the shipping industry by the Clean Air Task Force (CATF).

The study, “Bridging the Gap: How Nuclear-Derived Zero-Carbon Fuels Can Help Decarbonize Marine Shipping,” looks at how the shipping industry’s switch to nuclear power-derived hydrogen, or hydrogen produced fuels such as ammonia or synthetic fuels, can eliminate emissions.

Such a move will not be easy, however, and will need coordinated action by shipping companies, regulators, and nuclear energy providers.

The industry is struggling with a chicken-and-egg dilemma for the switch to zero-carbon fuels; demand will increase when there’s a reliable supply, but supply chains won’t switch until the demand is high enough to justify it.

“We looked at many options in the paper, from batteries to liquid natural gas, and it’s not just a case of turning a couple of wrenches but instead perhaps changing out a whole engine from a ship,” says co-author of the report and Director of Nuclear Innovation at the CATF, Brett Rampal.

“But, in a lot of ways, a similar sized engine with maybe a slightly larger volume for fuel capacity seems like a lower lift or easier barrier for the marine shipping market then perhaps some of the other zero carbon or low carbon options that we’re looking at.”

Re-envisioning future deployment models for nuclear for clean energy transitions 

(Source: Electric Power Research Institute "Rethinking Deployment Scenarios to Enable Large-Scale, Demand-Driven Non-Electricity Markets for Advanced Reactors".) 

Weighing alternatives

Alternative options such as natural gas and biofuels face their own problems. Both need major retrofitting, natural gas still emits CO2, and biofuels are produced from massive farming of land-intensive feedstocks like soybeans, rapeseed, and palm oil.

Meanwhile, even nuclear reactors that are running today, with slight modifications, can produce the temperatures needed for production of hydrogen, touted as one of the cleanest potential fuels for transportation.

Advanced and small modular reactors (SMRs), many of which are expected to begin commercial production by the end of the decade, will be even more efficient, ramping up hydrogen production through high temperature steam electrolysis (HTSE).

The work will come from the coordinated conversion by the shipping industry.

“Technically, there’s no barriers or hurdles (to converting ships to hydrogen). It’s a question of efficiency and cost and how we can balance those. It’s looking at the business model to incentivize the challenge of converting the fleet,” says Head of Reactors Strategy at the UK National Nuclear Laboratory Mark Salisbury.   

Modern shipyards are already primed to bring in modular reactors. The efficient, cost competitive fabrication of large ships through modular construction and assembly within the world’s shipyards could easily be utilized and repurposed for the manufacturing of SMRs, which could fit well into the world’s network of ship-fueling hubs.

“In terms of modular construction, nuclear doesn’t have a monopoly on construction techniques and it’s very good at learning from experience and looking outside itself. Shipbuilding is a great example,” says Salisbury.

“If you look at modular construction of aircraft carriers, or any large vessel, in the UK, we can take those techniques and use them for nuclear plants which will help with construction schedule and cost.”

Realizing the benefits

The United States is already funding research into nuclear-produced hydrogen and other synthetic fuels. Last year, the U.S. Department of Energy announced approximately $64 million in funding for 18 projects that will support its H2 @Scale project to “fully realize hydrogen’s benefits across the economy.”

In 2019, the DOE helped fund 29, H2 @Scale projects with a $40 million grant and awarded two grants for Exelon’s 1 MW polymer electrolyte membrane (PEM) electrolyzer for onsite hydrogen needs and to Xcel Energy and Energy Harbor to install an electrolyzer for onsite and offsite uses. 

In Britain, a recent report by the National Nuclear Laboratory, “Unlocking the UK’s Nuclear Hydrogen Economy to Support Net Zero”, laid out a cross-sector roadmap to reach 5GW of hydrogen generation by 2030 and 12GW, or 1,600 metric tons of hydrogen generation, per year by 2050.

Current modelling based on low-temperature electrolysis shows that just 3GW of nuclear generation could decarbonize half of Britain’s shipping fleet through hydrogen, according to July’s report.

Nuclear powered ships

As reactors get smaller, developers are also looking at cutting out the middleman entirely and using small nuclear reactors to power ships directly, as is already the case for nuclear submarines, and some ice breakers and aircraft carriers.

Since nuclear propulsion for marine vessels was first introduced in 1955, with the maiden voyage of the USN Nautilus submarine to Puerto Rico from the mainland United States, some 700 nuclear reactors have served at sea, say the Royal Academy of Engineering. Today there are around 200 nuclear reactors in service propelling ships and submarines.

However, their general use in commercial shipping is fraught with problems, most noticeably the regulation applied by each country’s nuclear regulator which could often be at odds with the ship’s flag-state authority.

Harmonizing international port regulations is key.

This summer, Britain launched a consultation on proposed regulation for nuclear-powered ships which seeks to transpose Chapter VIII of the International Convention for the Safety of Life at Sea (SOLAS) into UK law.

The Maritime and Coastguard Agency consultation aims to establish a regulatory framework that will support a legal framework for nuclear ships that may flag in the United Kingdom and for any visiting foreign nuclear ships nuclear-powered ships in UK waters.

By Paul Day