Zero emissions: The Nuclear Option

The ‘Nuclear Option’ may be shipping’s unspoken solution to Zero Emissions. In Part 1 of a two-part series James Clayton explains how emissions regulations, in combination with new developments in nuclear power, may point towards a propulsion technology whose commercial time has come. Part 2 will offer detailed insights into regulatory issues surrounding nuclear-powered ships.

Climate change is the defining issue of our time and in September 2019, the UN Climate Action Summit met in New York to outline a workplan for the shipping industry to commit to zero emissions by 2050. Emitting around 940 million tonnes of CO2 annually, the industry is responsible for around 2.5% of global greenhouse gas emissions (GHG).

At the same time, energy demand is on the rise from an expanding world population, with shipping likely to be a growing consumer. It is therefore surprising that, as shipping moves towards energy sources that produce fewer GHGs, the potential for the mass-application of nuclear power is seldom mentioned.

As is widely known, precedent exists for the use of nuclear propulsion in commercial shipping. In 1959, the NS Savannah, a 600ft, 12,000-ton ship was launched in New Jersey, USA as the world's first nuclear-powered cargo-passenger ship. Costing the United States government US$50 million (around US$440m today),  NS Savannah was built more to demonstrate the potential of nuclear energy in shipping than for commercial viability. Nevertheless, during six years in service, she travelled 450,000 miles and was visited by 1.4 million people. 

While several Russia nuclear powered ice-breaking ships currently operate, it is fair to say that the major champions of nuclear propulsion have been the world’s navies. In total, around 700 nuclear powered naval vessels have seen service; the United Kingdom, France, the U.S. and Russia have operated both nuclear powered submarines and surface ships, with India and China operating nuclear powered submarines. The deployments have been successful and safe; for example, the United States Navy lays claim to an accident-free nuclear record of over 5,500 reactor-years.

GHG issues

As ship emission regulations related to sulphur have continued to tighten, some of the alternative fuels proposed to take the place of conventional fuel oils have come with GHG issues attached. The vulnerability of liquefied natural gas to methane slip, for example, has led some to conclude that its GHG footprint is actually larger than conventional fuel oil.

Hydrogen, methanol and ammonia have also been suggested as viable alternatives but there is strong new evidence to suggest that, on capex, opex and environmental grounds, nuclear energy emerges as the most promising power source for the shipowner seeking to reduce GHGs.

Changing the terms of reference have been technological advances with liquid fluoride thorium reactors (LFTR). Cheap, small and light, research suggests LFTRs could reduce negative impacts on health, safety and the environment by more than 50% and climate change externalities by more than 90% when compared to LNG. Equally, when compared to conventional nuclear reactors, LFTRs are the optimum choice as they have a fuel efficiency of around 99% and meltdown is not possible given the fuel is liquid in form.

Confinement against radioactive leakage has also been developing and the complete recycling of a nuclear ship on decommission is now possible. While conventional nuclear waste must be stored for thousands of years, the waste products from a LFTR would return to background radiation levels after being stored for 300 years.

Economic arguments go nuclear

Recent market developments add economic weight to arguments in favour of nuclear propulsion. With HFO and other combustible fuel prices once more on the rise, and the likelihood of more substantial taxes on emissions and bans on sulphur containing fuels, the competitive position of nuclear power has improved.

While substantial initial investment would be required, considerable long-run savings would be available. Vessels would need to spend less time refuelling and when they did, nuclear fuel is a relatively inexpensive product. Space previously required to store bunkers could be used to carry additional cargo. Importantly, nuclear powered vessels would be able to achieve faster transit times, giving them a considerable competitive advantage and allowing them to charge a premium for carriage.

Practical issues

Likely early candidates for nuclear propulsion systems include ultra-large container ships because the high-power outputs available would complement the operational profiles of these vessels in a cost-efficient manner. As they predominantly ply liner trade routes, only the relevant ports of call would need to adapt, meaning that the number of ports handling nuclear powered ships (with higher safety standards, systems for refuelling, the ability to carry out repairs etc.) would be limited.

Alternative methods of implementing nuclear propulsion have also been discussed and would allow for nuclear powered vessels to access ports that have not been adapted. For example, modular nuclear vessels could be developed, whereby the nuclear plant separates from the vessel and waits outside territorial waters while docking and cargo transfer takes place. Alternatively, nuclear ‘super tugs’ could provide high-speed towage services across oceans while leaving the conventionally propelled vessel to enter territorial waters and dock on its own.

While there are undoubtedly hurdles that must be overcome before nuclear power can be adopted within the shipping industry, its sustainability from both environmental and economic standpoints suggest that it is a propulsion option that has for too long been neglected. Full consideration will be given to the regulatory issues surrounding nuclear powered ships in my following article: The Nuclear Option: Shipping’s Unspoken Solution to Zero Emissions? (Part 2). Ultimately, it is an option demanding a first mover to prove how viable it really is.



(3rd IMO GHG study);

J. A. Angelo, Jr. Nuclear Technology (Greenwood, 2004)