Taking shipping back to the future

A speculative case for nuclear-powered cargo ships

Welcome readers old and new. This is one of Thomas Hollands’ notes in his search for ideas which are surprisingly general, or generally surprising. The first issue explains the project, and you can find all past issues here.

We are all addicted to globalisation.

In the 60s, widespread container shipping sent transportation costs plummeting, allowing markets to become truly global. Today, Amazon and Alibaba have ensured that we can order almost anything we like, to anywhere in the world.

Last week we explored a crucial technology which made globalisation possible: the shipping container. Globalisation and the wealth it brings is a helluva drug, but like all drugs it has side effects. In this case, the side effects are truly severe - our addiction to globalisation is killing the planet.

Three reasons why maritime transport must act on climate change

The shipping CO2 emissions outlook does not look good. Source: World Bank

The very process by which we move goods around the world pollutes it. Some environmentalists argue that to stop climate change, we must defeat our addiction and renounce increasing economic growth. But the globalisation ship has sailed. In the West we are too dependent on cheap mediterranean produce, South Asian clothing, and Chinese electronics to go back to a de-globalised world.

There is another way. A way we could have more trade, cheaper and faster, while reducing the CO2 emissions from trade to virtually zero. This new way requires no new scientific breakthroughs - the technology has existed since the 60s. Only a few unhappy accidents prevented us from harnessing it then.

The way of nuclear powered shipping.

I am a nerd for nuclear. I want nuclear powered container ships. But we also need nuclear powered container ships. This post lays out why.

I'll start by recapping the container shipping industry. Then I'll describe a super abridged history of nuclear shipping, from deep-sea submarines to Arctic icebreakers. These icebreakers will play a greater role in international trade as Arctic sea ice melts and new trade routes open up - I'll highlight some of these key trade routes. Next, I'll talk about an environmental feedback loop which explains why using fossil-fuels on these routes will wreck the environment even faster. And finally, I'll explain why nuclear container shipping doesn't already exist, and outline some steps we could take to make it possible.

It's a meandering journey, but (I believe) an interesting and important one. So let's begin.

The ships

Container ships are absolute behemoths. The biggest container ships are over 400 metres long, and 60 metres wide, and are able to ship over 18,000 containers in one go. Until recently, container ships were at least constrained by having to fit within the Panama canal. But now, so-called Supermax ships are too voluminous to squeeze through.

Mærsk Mc-Kinney Møller.jpg

One of Maersk’s “Triple-E” ships. The three Es are “Economies of scale”, “Energy efficient”, and (lol) “Environmentally improved”. Source: Wikipedia.

These absolute units are powered by diesel engines, and produce an enormous amount of pollution. The 15 biggest container ships emit roughly the same amount of CO2 as all of the cars in the entire world.

The key number dictating the economics of shipping (and hence the pollution of shipping) is the "cost per box" - the cost of shipping a full container from point A to point B. This is mainly influenced by how idle each ship is, and how efficient it is at loading and unloading containers. Bigger ships are more efficient at unloading containers, because they have the same setup times as smaller ships but have more containers to unload. They spend a higher proportion of time in port loading and unloading, and less time being idle. Factors like the journey distance and ship's velocity also matter, but are very route dependent. The most reliable way to lower cost per box is to build ships which can carry more boxes.

For container ships, size really does matter.

The future that almost was

We were close to having widespread nuclear shipping. In the 50s, President Eisenhower heralded a plentiful future, with "energy too cheap to meter". Nuclear power was supposed to be an integral part of this future, and nuclear ships were already being built.

Militaries have been using nuclear energy to power their vessels for a long time. The earliest US nuclear submarines were built in 1955, and they added a new dimension to marine warfare. Nuclear submarines could reach much higher speeds than their fuelled counterparts, and were the first true "underwater" vessels, able to remain submerged for months without refuelling. Nuclear energy also enabled building massive aircraft carriers, mobile fortresses which could stay at sea for decades without refuelling.

In 1962, nuclear shipping went commercial. The NS Savannah sailed under the Golden Gate bridge, before making its maiden voyage to Hawaii, touring the United States via the Panama canal. Guests from around the West sailed across the Atlantic on the Savannah until its decommissioning in 1971.

Savannah was built as a demonstration. Its interior and exterior were designed to be visually striking (not like ugly container ships), and because its nuclear engine produced no exhaust smoke, it dazzled onlookers, looking resplendent when first arriving in port. Savannah was subsidised by the government, and with its high maintenance costs and design tradeoffs, was never intended to be commercially competitive.


The Savannah had "Atomic Age" Star Trek-like interiors.

The Savannah was only one of four nuclear cargo ships ever built. She was decommissioned to save costs, and in 1971, fuel oil only cost $20 per ton. In 1974, at $80 per ton, the Savannah would've beaten most Diesel merchant ships, able to travel double their speed, spending less time in port, at the same cost.

In the 70s non-military nuclear shipping found its first serious use case. At the peak of the Cold War, the USSR used nuclear power to break ice along its northern coastlines, allowing marine trade between Vladivostok and Moscow in the winter.

Nuclear icebreakers, like nuclear submarines, are far better than their Diesel counterparts. They can travel at faster speeds, breaking ice faster. They only need refuelling once a decade, a big advantage in the desolate Arctic.


Nuclear icebreaker Yamal. This fella's got heft.

In 2012, Russia's state-owned nuclear corporation, Rosatom, began construction on what they describe as "the largest nuclear icebreaker", a "universal" vessel that will be able to navigate both shallow rivers and the frozen Arctic.

Now that climate change is reshaping the Arctic, ships like these are becoming far more important.

Going nuclear in the Arctic

Arctic sea ice is melting faster than ever. This is terrible for the planet but great for trade - because new routes through the Arctic are beginning to open up.

The Northern Sea Route, linking the Kamchatka peninsula in eastern Russia to Alaska, lies exclusively in the Arctic circle, and at the moment is free of ice for only two months per year. With the effects of climate change, direct trade between Europe and the US within the Arctic is becoming possible, shortening current journey times via the Suez canal by 2-3 weeks.

Some maritime executives (notably Chinese ones) are already thinking 20+ years ahead, when there will be so little Arctic sea ice that it will be possible to ship cargo directly through the North pole. If successfully sustained, the Transpolar passage will cut thousands of kilometres off journeys from Asia and the US.


When the sea ice goes, the spice must flow. Source

Shipping through the Arctic is guaranteed to happen. The Russian and Chinese governments have already factored it into their plans, and it makes basic economic sense. But if we do this shipping with the Diesel-powered ships which are industry standard, we will melt sea ice faster and faster, ruining the environment in an accelerating flywheel of destruction.

Sea ice is a vital part of the global climate. Ice has a higher albedo (reflectivity) than seawater. Sea ice reflects most of the sun's heat back up into the atmosphere, while seawater mostly absorbs the sun's heat, slowly contributing to global warming. As sea ice melts, more energy-absorbing water is exposed, which increases the amount of heat the earth can absorb. This continues in a positive loop called ice-albedo feedback.

Burning Diesel fuel doesn't only increase the concentration of CO2 in the atmosphere, but it also produces soot. Soot is bad for your lungs, but terrible for sea ice. Covering sea ice in soot turns it grey, drastically reducing its albedo, making it absorb more heat and melt even faster.

To stop global warming, we need to slow down the ice-albedo feedback loop. The only way to propel ships rugged enough to traverse the Arctic without polluting it is with nuclear power.

Cheaper, faster, cleaner

Nuclear powered ships would enable faster transport, which would lead to cheaper costs, and operating them would be cleaner for the environment.

Nuclear reactors can provide far more power to a ship than Diesel engines. Ships could travel at faster speeds, reducing journey times, and in some cases potentially cutting them in half.

Reactors only need refuelling once a decade, which could potentially cut down on un-utilised time ships need to spend refuelling in port.

Both of these factors would result in a reduced cost per box and hence lower transportation costs. And most importantly, nuclear ships could provide these improvements without emitting CO2 into the air and sullying sea ice with soot.

Why they don't already exist

At this point, I can hear you saying: Ok nuclear powered ships seem kinda cool. But if they're so great, why don't we use them already?

Nuclear powered ships aren't already widespread for two reasons:

  • (Old) Nuclear reactors are (prohibitively) expensive to install and maintain

  • (Old) reactors are perceived to be unsafe to operate, unsafe to dispose waste, and carry a risk of proliferating weapons-grade nuclear material

I'll now try to convince you why these concerns are less severe today.

All nuclear ships I've come across run on pressurised water reactors. The water which cools down the super-hot solid uranium core has to be kept at a high pressure. These reactors require constant maintenance. One small instability in the reaction could lead to an explosion of the pressurised water. If a problem happens, they are unsafe. As a result, they are expensive to maintain.

New generations of nuclear reactors are far safer.

Molten salt reactors are made up of a liquid salt which undergoes fission. The coolant is also a complicated compound, surrounded by water at atmospheric pressure. Since the water is at normal pressure, there is little danger of an explosion. If something happens to the reactor, the molten salt can flow straight into a lead containment box which insulates the rest of the world from the fission reactions in the salt. It is designed to be safe by default.

Most importantly, molten salt reactors undergo different reactions than pressurised water reactors, which results in waste products with shorter half-lives which are much easier to dispose.

Disposing nuclear waste is a legitimate concern. I'm not going to address it here, other than to say that the total amount of nuclear waste in the world, from 70 years of reactors providing terawatts of energy takes up less than one football field in volume. I'd be quite happy to fill a Siberian sinkhole with nuclear matter and leave it the fuck alone.

There are other next-generation reactors like pebble bed reactors, all of which are safer, and operate at higher efficiency than the legacy reactors used in nuclear vessels today. These reactors still require upkeep, but because they're much safer, they require less constant maintenance. After installation, they should cost far less to run.

Thanks to decades of advances in reactor technology, there are no technical barriers to building safe, competitive, nuclear powered ships. The only barriers that remain are cultural.

How to make it happen

If you've made it this far you hopefully think free trade is great, polluting the environment is bad, and nuclear container ships could give us free trade with far less pollution. The road to fossil-fuel free, faster, trade is simple:

  1. Build prototype next-gen reactors, demonstrate they are safe and have a lower cost of maintenance. (Already being done across the world)

  2. While this is going on, change the nuclear narrative. Educate people that nuclear energy is safe, fossil-free, and the only long-term solution to climate change

  3. Build a prototype US coastguard icebreaker for the Northern Sea Route

  4. When this works, build reinforced Arctic nuclear cargo ships

  5. Phase out older container ships and replace with nuclear ones


Ok, so I don't really know for sure whether nuclear powered container ships are the future. There are still some risks - chief among them is working out how to dispose of nuclear waste. But I think they're super cool, and they genuinely seem like the only way we could sustainably keep up global trade. Diesel is far too polluting, and renewables like solar cannot provide enough power.

The only way we can keep the fruits of our globalised lifestyle without destroying our garden planet is to go nuclear.

If we go nuclear, we can take shipping back to the future: making global trade cheaper, faster, and cleaner.

I will discuss how we can concretely improve our material world in future issues of this newsletter. If this is something that tickles your fancy, please subscribe.

The Relativity of Wrong

I have been thinking about this Isaac Asimov quote recently. I present it to you with no further comment:

John, when people thought the earth was flat, they were wrong. When people thought the earth was spherical, they were wrong. But if you think that thinking the earth is spherical is just as wrong as thinking the earth is flat, then your view is wronger than both of them put together.

The full essay is worth reading here.