Is transporting pressurized hydrogen by ship a good idea?

Although the investigation is still ongoing, and we will have to wait for it to be completed before drawing any conclusions, the mishap aboard the first ship to transport hydrogen has brought attention to a technology that experts say has no future.

We saw how Australia and Japan welcomed the announcement of the first shipment of a ship carrying liquid hydrogen just a few days ago. The International Renewable Energy Agency, as well as the German expert organization Agora Energiewende and energy analyst Wood Mackenzie, all stated at the time that operating a ship laden with liquid hydrogen makes no sense from a physics or economic standpoint.

We must now add the argument of security to these considerations. And it’s because the ship caught fire before making its first voyage from Australia to Japan.

The Australian Transport Safety Bureau (ATSB), which is in charge of investigating air, maritime, and rail accidents in Australia, has opened an inquiry into a “severe event.”

According to the earliest publicly available information, the inquiry will focus on a breakdown of the gas carrier Suiso Frontier’s hydrogen pressure control system during the first loading of liquefied hydrogen in the Australian port of Western Port, Hastings.

This event may have served as a learning opportunity concerning large-scale high-pressure hydrogen storage technologies, but it has also served as a warning of the dangers that this technology entails both onboard ships and at ports where hydrogen is carried and unloaded. vector.

Save Westernport, a local environmental group has labeled the port complex as “one of the most dangerous infrastructures in the area,” noting that it is “within reach of the city of Hastings’ residential districts.”

An event aboard the ship has been condemned for the lack of openness of corporations and government agencies, which have kept the incident concealed until now, two months after it occurred and after the ship had completed its first voyage between Australia and Japan.

This incident has also fueled controversy over the most acceptable and safe manner to transport hydrogen over long distances, with studies indicating that shipping hydrogen in the form of ammonia would be cheaper than liquid.

The experts’ reasoning for choosing this approach is based on three main factors. Ammonia is preferred for long-distance exports due to its high energy density, well-proven synthesis process, and established supply networks.

Liquid hydrogen supporters argue that its energy density is unrivaled when compared to other fossil fuel alternatives. “This superiority is useless since liquid hydrogen must be carried in big metal containers, so what truly counts is its energy density by volume,” according to the consulting company Mackenzie.

Because hydrogen has only 3kWh of energy per cubic meter at normal atmospheric pressure, it must be compressed or liquefied to enhance its energy density to 1,411 kWh/m3 (at 700 bar pressure) or 2,350kWh/m3 when chilled in liquid at minus 253 °C.

When held in its ordinary liquid form at minus 33.3 °C, ammonia has a volumetric density of 59 percent higher: 3,730 kWh/m3.

On paper, it would take more than three shipments of liquid hydrogen (LH2) to transport the same amount of energy as two shipments of ammonia using ships of similar size and capacity.

It’s also important to consider a little-known but crucial component. This is the rate of evaporation of liquid hydrogen compared to ammonia. Transporting 160,000 m3 of liquid hydrogen from Qatar to Japan would result in an annual evaporation rate of 13.77 percent, according to studies published in the journal Energy Reports. Over the course of a year, this translates to a loss of 13.77 percent of your cargo weight (24 trips). A ship transporting 160,000 m3 of liquid ammonia on the same journey, on the other hand, would lose just 0.325 percent of its cargo weight to evaporation.

The decreased cost of ammonia manufacturing is also a plus. According to the Recharge webpage, a shipment of liquid hydrogen weighing 160,000 m3 (the size of a conventional LNG ship) would cost roughly $200 per MWh. A number that may be compared to the cost of a shipment of liquid ammonia with equivalent qualities, which would cost less than 88 dollars per MWh.