ENVIRONMENT

Intro: A start-up in America is developing world’s first ammonia-powered ships

THE Brooklyn Navy Yard’s sprawling industrial complex once employed 70,000 workers to build US battleships and aircraft carriers during the second world war. Almost 80 years later, it has become home to a New York city firm with a very different maritime mission – harnessing ammonia as a low-carbon fuel for the global shipping industry.

The start-up Amogy has already shown how ammonia-powered technology can work in a flying drone, a John Deere tractor and most recently a truck. Now, it is working on an ammonia-powered ship.

Most ships currently run on fossil fuels that emit greenhouse gases, accounting for 3 per cent of the world’s carbon emissions. One alternative involves converting vehicles to hydrogen power that would only emit water. But hydrogen gas needs to be compressed and liquified at -253°C for storage and transportation.

Ammonia could serve as an alternative hydrogen-bearing fuel that is more easily stored and transported in a stable liquid form at room temperature.

Hydrogen can be extracted by heating ammonia to high temperatures, which is a process that comes with its own energy cost. This is where Amogy’s technology comes in. To make ammonia power more viable, the company has developed what it describes as a more efficient and miniaturised “ammonia cracking” method that can chemically extract hydrogen from ammonia at a lower temperature. It uses a proprietary catalyst to speed up the process inside a chemical reactor that feeds into a hydrogen fuel cell.

A leading chemist at Saint Mary’s College of California says that what Amogy was able to bring to the table is that by having better catalytic technologies (all proprietary) they were able to miniaturise their ammonia cracking units and put them on board vehicles.

It was in July 2021 when Amogy first showed that its system could supply 5 kilowatts of power to a drone. By comparison, a standard ammonia cracking system for extracting that amount of hydrogen power is usually the size of a large shipping container. It also paved the way for a 100-kilowatt tractor demonstration in May 2022. That was followed by a 300-kilowatt truck demonstration in January 2023. The firm is now working towards demonstrating a 1-megawatt system in a tugboat.

Many countries already have pipelines and port facilities for handling ammonia that is produced industrially as fertiliser for agriculture. The US alone has more than 5000 kilometres of ammonia pipelines compared with 2500 kilometres of pipeline for transporting hydrogen – though it will need more to support ammonia-powered vehicles.

Another challenge is that ammonia still “has a carbon footprint associated with the production” because the standard industrial process uses natural gas. Low-carbon ammonia production would require use of carbon capture.

Cleaner alternative methods could ideally use electricity from renewable power sources to split water into hydrogen for conversion to ammonia.

. Science Book: Chemistry