SPECIAL REPORT | Burns, blindness and agonising deaths: is it safe to ship hydrogen-derived ammonia around the world?

Irena also states that in its 1.5°C pathway, the demand for ammonia would increase fourfold by mid-century to 688 million tonnes — with 197 million tonnes of that used as a shipping fuel and 127 million tonnes as a hydrogen carrier.

Safety at sea

One of the problems with dramatically scaling up the shipping of ammonia is that as more vessels take to the high seas, the likelihood of a serious incident grows.

“Two dozen ships go down every year and if 40% of them were carrying ammonia to replace fossil fuels as the way to transfer energy, then that would be ten ships a year. [Even] if you had half or a quarter of that… you’ve still got a lot of ammonia ending up in the ocean.

And make no mistake, ammonia is nasty. It is a caustic, water-seeking chemical that attaches itself to moisture — including in a person’s eyes, mouth, lungs, throat or skin.

Exact exposure limits vary from regulator to regulator but even very low concentrations in the air of just 30 parts per million (ppm) — possible from a very small leak, or even sometimes regular operation — can cause breathing difficulties if a person is exposed to it for more than 15 minutes. At 100ppm, eye and throat irritation will occur, and at 500-700 ppm any exposure at all becomes dangerous, with a risk of burns to throat, skin, lungs and eyes, potentially causing blindness. At higher concentrations, the risk of death increases significantly.

Severity of injury depends on the exact concentration of ammonia and length of exposure but in a worst-case scenario it can cause the respiratory tracts to burn and swell shut, suffocating the victim.

It doesn’t end there. When ammonia spills — for example, in a collision at sea that causes the tank to rupture — and especially if hits water, it reacts with condensation in the air to form a heavy, toxic mist that does not dissipate.

An ammonia gas cloud is “very difficult to handle”, explains George Mallouppas, associate scientist at the Cyprus Marine and Maritime Institute (CMMI), noting that while a port or industrial area can be evacuated to avoid a spill cloud, it is “nearly impossible” to do so on a vessel at sea.

And while ammonia is significantly less flammable than liquefied natural gas (LNG), it is nevertheless flammable, so any leak at sea would be accompanied by a risk of explosion or fire.

A serious ammonia spill would also be devastating under the waves. Ammonia dissolves in water to form ammonium hydroxide, which is highly toxic to marine life.

The effects would be worse if the spill happened in a bay or port, where naturally-occurring ammonia levels are already raised due to high levels of decomposing organic matter on the seabed and low water exchange, says Manos Moraitis, assistant scientist at the CMMI’s Marine and Coastal Ecosystems Centre.

Good safety record to date?

And as recently as last month, Carlsberg was fined £3m ($3.6m) by UK regulators for an ammonia leak from one of its breweries, which killed one and seriously injured another.

The remaining three, however, were fatal accidents — all on fishing vessels where ammonia used as an on-board refrigerant either leaked or exploded.

But Cebon warns that the probability of more accidents as a result of the expected expansion in ammonia transport will be amplified by the lack of effective regulation at sea — as well as official incompetence, inaction or corruption.

And the explosion of ammonium nitrate in Beirut, Lebanon, in August 2020 — which killed 218 people due to official negligence — demonstrates the catastrophic consequences of a single failure relating to hazardous substances, even if it is handled carefully and safely by the vast majority of those who use it.

Human error is, according to Together in Safety, a contributing factor in 75-96% of incidents at sea, as extended periods onboard and time away from loved ones erode crews’ effectiveness.

This risk factor is further exacerbated by the need for well-trained staff with specialist knowledge on how to handle ammonia — which some shipping companies may not be able or willing to splash out on.

Martin goes even further. “The big risk of ammonia as a bulk energy carrier is terrorism,” he says. “A tanker harboured in a location near a populated area would be a tempting target and could produce deaths and injuries on a catastrophic scale.”

Risks grow when using ammonia as fuel

Another problem for ammonia’s relatively clean safety record is that its use as a fuel is relatively new and untested — and is inherently more risky.

Unlike cargo ammonia, which is carried onboard in a sealed tank, ammonia used as a fuel will be integrated into the operation of the vessel.

This means pipes carrying fuel from the tank to the fuel preparation room (the space containing pumps, compressors, etc) to the engine — maximising the surface area that could leak or sustain damage.

It means ammonia burning in an engine that could leak or explode. It means an engine room with crew working in it, who could all be exposed to leaking fuel. It means fugitive ammonia emissions from the engine escaping out of the exhaust.

The good news is that LNG has already made the transition from cargo to fuel relatively safely, so there is a model to follow for other liquefied gases.

“The crew involved must be properly skilled, upskilled or reskilled in order to meet the specific requirements of handling a new fuel with physical and chemical properties and behaviour significantly different than the established marine liquid fuels,” explains Professor Elias Yfantis, senior scientist at CMMI’s Marine and Offshore Science, Technology and Engineering Centre.

DNV suggests a number of mitigation measures to make ammonia safe to load, transport and burn at sea.

Firstly, it suggests locating the ammonia tank away from ship and cargo operations, and “carefully” considering placement to minimise risk from external events, such as grounding or collision. It also recommends gas-tight secondary barriers around the tank, pipes and the engine, to contain any potential leaks and stop them leaching into areas where crew might be operating.

At port, loading and unloading of ammonia should be carried out as remotely as possible, and carried out with well-trained staff, using specialist hose couplings that reduce the risk of leaks. DNV adds that fuel-loading hoses should be purged with inert gas to flush out any residual ammonia.

And in the event that any of these systems fail? Mallouppas is confident that leak detection systems on the market today are up to the job of alerting crew to potential leaks, allowing them to intervene before the situation escalates.

“There are commercially available sensors and clever systems that are mature enough to detect leaks quickly enough,” he says. “The response time would be as quick as any other system that detects leaks. There are also new systems that will need to receive approval.”

Martin is less optimistic when asked about the likelihood of effective regulation. “I’m confident that we could do so, but I’m also confident that we would not do so until after a significant loss of life forced the imposition of regulations,” he says.

It is hard not to draw comparisons with nuclear power. Like ammonia, nuclear has the potential to decarbonise vast swathes of the energy system and has a relatively good safety record — but this does very little to calm public anxiety about the potentially catastrophic consequences that could occur.

Like nuclear power, ammonia also has no room for manoeuvre on safety. It will require a gargantuan effort and significant investment from shipping companies, engine-makers and naval architects — as well as politicians and regulators — to ward off even one devastating accident.