The race is on to build the world’s first ammonia-powered ship

Startup Amogy is retrofitting a tugboat in New York, while several Nordic companies are testing out different ammonia technologies for cleaning up the shipping industry.

Two cargo ships in the ocean piled high with colorful cargo containers
(Allen J. Schaben/Los Angeles Times/Getty Images)
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Ammonia is predicted to become the leading fuel source for the world’s giant cargo ships by 2050. Yet no vessel actually runs on the pungent, carbonless compound today. In labs and shipyards around the world, companies are working to build the first ammonia-powered ships as the maritime industry scrambles to replace dirty diesel fuel with cleaner alternatives.

In Norway, two high-profile projects are well underway to retrofit vessels that supply offshore oil-and-gas operations. One ship will use an ammonia-burning engine, and the other will have an ammonia-powered fuel cell — both novel technologies. In China, a shipyard recently built the first ammonia-ready” vessel, meaning that when the ship eventually switches from using oil to ammonia, it will already meet the necessary safety criteria. 

Now, a new contender has joined the race to make ammonia shipping a reality.

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Amogy, a startup based in Brooklyn, said it is converting a red-and-orange tugboat at a shipyard in New York state. The 65-year-old vessel currently has diesel generators and electric motors. Later next year, it should be sailing up an inland waterway using Amogy’s ammonia-to-power system, the company told Canary Media.

A rusty red and orange tugboat
Amogy’s New York tugboat was used by the U.S. Navy for decades. (Amogy)

Getting the first vessel on the water will be a really important step toward zero-emissions shipping,” said Christian Berg, who joined Amogy in September from Yara Clean Ammonia, a subsidiary of the Norwegian chemicals giant Yara International.

International shipping accounted for about 2 percent of global energy-related carbon dioxide emissions in 2021 — a percentage that’s expected to climb as more vessels deliver more goods and as other sectors reduce their share of global emissions. The vast majority of today’s ships burn highly polluting petroleum-based fuels. Tens of thousands of freighters spew not only carbon dioxide emissions and methane but also air pollution, which threatens the health of people living near ports.

Cargo owners, regulators and environmental groups are ratcheting up pressure to curb emissions from cargo ships. In response, the industry has started to significantly scale up investments and research efforts to advance alternative fuels such as ammonia, hydrogen, methanol and battery power, as well as energy-saving devices like wind-snatching kites and rotor sails.

Most recently, at the U.N. climate conference in Egypt this week, the United States and Norway organized the Green Shipping Challenge to accelerate adoption of low- and zero-emissions fuels and promote uptake of next-generation vessels. As part of the challenge, companies, countries and ports announced more than 40 initiatives — including efforts to establish a green-fuel corridor between Singapore’s maritime authority and the ports of Los Angeles and Long Beach in California.

Shipping is a major emitter of greenhouse gases globally, therefore it’s vital that quick and decisive action is taken at scale to reduce emissions from this sector to help limit temperature rise to 1.5°C,” Jonas Gahr Støre, prime minister of Norway, said in a statement. (At present, the world is on a path to reach 2.5°C of global warming.)

Ammonia has potential — and major challenges — as a marine fuel

Amogy’s tugboat retrofit will mark a tiny but important milestone in the broader quest to clean up cargo shipping.

The startup plans to install a 1-megawatt version of its ammonia-to-power system, which will be 10 times larger than the unit that Amogy field-tested on a John Deere tractor this summer. The company said it is still determining where in New York it will test the tugboat, and it’s working now with regulatory parties to identify potential hurdles to sailing the first-of-its-kind ship.

the interior of an old tugboat
Work is underway to install Amogy’s ammonia-to-power system inside the tugboat’s engine room. (Amogy)

Amogy has raised $70 million since launching in November 2020 from investors including Amazon, Saudi Aramco and South Korea’s SK Innovation. 

In September, the company opened an office in Norway and brought on Christian Berg to establish ties to the region’s shipping industry, which is leading the global push on ammonia-powered shipping — mainly because governments are investing heavily in technology development and setting stringent rules for curbing ship emissions. This week, Amogy announced a collaboration with Yara Clean Ammonia on shipping projects.

In the Nordic countries, shipowners are already talking about ammonia on a daily basis, which is not the case here,” Amogy CEO Seonghoon Woo said in June during a demonstration at the startup’s Brooklyn facility.

Ammonia (NH3) is mainly used today to make fertilizer, plastics and cleaning products. But shipping companies and researchers see it as a promising fuel for a few key reasons.

Because the compound doesn’t contain carbon atoms, it doesn’t produce carbon dioxide when used as fuel. Compared to other alternatives, such as liquid hydrogen or battery power, ammonia is relatively energy-dense, meaning it requires far less space to store on board. And because ammonia is already a widely traded commodity, the global infrastructure needed to produce, store and transport ammonia is already in place, including at some 130 ports worldwide.

Under the International Energy Agency’s most ambitious scenario for cutting global emissions, ammonia would meet nearly 50 percent of shipping fuel demand in 2050. Biofuels and hydrogen would fill 20 percent and 15 percent of the fuel demand, respectively, while fossil fuels would make up the final 15 percent of fuel consumption in the agency’s net-zero emissions scenario. 

We view ammonia as a good candidate for decarbonizing long-range transoceanic journeys,” Elizabeth Connelly, an energy technology and transport analyst for IEA, said during an October symposium held by the U.N.’s International Maritime Organization.

Ammonia does have several major drawbacks, though.

Nearly all of today’s ammonia supplies are produced using fossil fuels in highly energy- and carbon-intensive processes. Ammonia manufacturing alone contributes 1 to 2 percent of all global carbon dioxide emissions. The compound is also highly toxic and corrosive; if it spills or leaks, it can be deadly to people and aquatic life. Burning ammonia in engines can also yield air pollutants and small amounts of nitrous oxide, a potent greenhouse gas.

Experts say it’s possible to manage such challenges. To start, ammonia can be produced using only electricity generated from wind, solar and other renewable sources. Small facilities are already making green” ammonia in Britain and Japan, while pilot projects are planned in the United States, Norway, Australia, Egypt and Saudi Arabia. Engineers are developing on-board fuel systems with added safety layers to protect people and ecosystems, and they’re designing filters for harmful engine byproducts.

For now, however, one of the biggest barriers to ammonia-powered shipping is the lack of mature technologies. Ammonia-burning engines are still in the prototype phase. The type of fuel cell that works best with ammonia, known as solid-oxide, is in a similarly early stage of development.

Both innovation for new technologies and progress in existing technologies will be needed to substantially reduce shipping emissions in the long term,” Connelly said, as well as [to spur] the development of supporting infrastructure.”

First-mover ships could help speed up ammonia adoption 

Amogy is hoping its unique approach will give it a leg up in the shipping race.

The company is developing a chemical reactor that takes ammonia stored in fuel tanks and cracks” the compound into its constituent parts of hydrogen and nitrogen. The hydrogen flows through a fuel cell, which converts chemical energy into electricity to drive the motors. While ammonia is more energy-dense, hydrogen is more compatible with the most common type of fuel cell: polymer electrolyte membrane. The idea is to harness ammonia’s density and hydrogen’s usability by tapping into both. 

Amogy will speed up the whole process of using ammonia as fuel, because they have the technology to do so,” Berg said.

Larger ships being retrofitted to use novel ammonia technology are expected to follow closely in the tugboat’s wake.

Starting next year, the Finnish manufacturer Wärtsilä will begin selling a marine combustion engine that is capable of using a fuel blend of ammonia and marine gas oil,” a low-sulfur petroleum product commonly used in ships. The engine can reduce greenhouse gas emissions by 70 percent compared to a conventional engine burning only marine gas oil, according to Wärstilä.

A laboratory with industrial testing equipment
A Wärtsilä engineer performs early combustion tests using ammonia fuel blends. (Wärstilä Marine Power)

The company is partnering with Norwegian shipping firm Eidesvik Offshore to retrofit a supply vessel with an ammonia combustion engine. The conversion will allow the ship to use a fuel blend with up to 70 percent ammonia. (Because ammonia is difficult to ignite, engines will still need to use a liquid pilot fuel like diesel or hydrogen, ruling out the use of 100 percent ammonia.) The companies are aiming to complete the so-called Apollo project in late 2025.

Wärtsilä and Eidesvik are also part of Norway’s ShipFC project, which involves installing a 2-megawatt fuel-cell system on a supply vessel called Viking Energy. The fuel cell will be solid-oxide, which can operate at high temperatures of about 1,000°C and use ammonia directly to power electric motors. That ship is set to begin operating on ammonia in 2024.

While companies are starting to put engines and fuel cells on actual ships, still more work is underway in test facilities. Wärstilä is researching several types of ammonia combustion technology, which involves combining either liquid or gaseous forms of ammonia with marine gas oil in full-scale 4-megawatt marine engines at facilities in Stord, Norway and Vaasa, Finland.

I strongly believe that there are no huge obstacles to the technology,” Egil Hystad, general manager of market innovation at Wärtsilä Marine Business, said in an interview.

As he sees it, other elements — such as green ammonia production, refueling infrastructure and economic factors — are needed to spur wider adoption of zero-emission shipping fuels. Shipowners need to know that ammonia supplies will be available wherever they pull into port. They’ll also need to see more demand from their cargo owners before making hefty investments in next-generation ships.

The engine is a vital enabler, but the value chain is what we need to establish if we’re going to do a radical decarbonization in shipping,” Hystad said. All of these have to take place at the same time.”

Watch Canary Media reporter Maria Gallucci give a TED talk on green ammonia and shipping.

Maria Gallucci is a clean energy reporter at Canary Media, where she covers hard-to-decarbonize sectors and efforts to make the energy transition more affordable and equitable.