World’s First Ammonia-Fueled Ship Hits a Snag

One of the biggest environmental concerns with ammonia-powered ships is the potential release of nitrogen oxides. “Instead of CO₂, which contributes to global warming, we could end up with nitrogen oxides, which are lethal to breathe,” says Prousalidis. “To avoid simply swapping one pollutant for another, ammonia propulsion systems must include emissions-control technologies to prevent harmful nitrogen oxides from entering the atmosphere,” he adds.

A promising alternative to combustion engines is ammonia-powered fuel cells, which generate electricity without producing nitrogen oxide emissions. By avoiding combustion entirely, these fuel cells allow ammonia’s nitrogen content to remain in its inert form, eliminating a key health risk.

Ammonia Fuel Delays for Viking Energy

Despite the challenges, experts believe ammonia could become a mainstream maritime fuel—but not overnight. “Twenty or thirty years ago, the shipping industry made a major shift to natural gas, believing it was the fuel of the future. Now, we know it wasn’t the right step,” says Prousalidis.

Looking back at past fuel transitions, he noted that each shift—from steam to oil, and then to natural gas—took around 20 years to achieve full adoption. He expects a similar timeline for the adoption of ammonia or hydrogen. “We need to be patient while persisting in our efforts and not getting discouraged by early challenges.”

That perspective aligns with what Equinor’s vice president of renewable and low-carbon technology, Henriette Undrum, told IEEE Spectrum in 2021 when she urged the public to be patient: “We are not just solving one small problem for one ship. It’s part of the bigger picture. It will be a starting point to build up the market for zero-carbon fuels.”

As ammonia and hydrogen gain traction as maritime fuels, seaports could play a pivotal role in in solving ammonia’s chicken-and-egg problem. Energy companies are wary of investing in alternative fuel infrastructure when there aren’t any ships that run on the new fuel, and shipbuilders are want to avoid shelling out hundreds of millions of dollars to build vessels for which there is no steady fuel supply.

“Seaports are already undergoing an energy transformation,” says Prousalidis. “It would make sense for them to operate as energy hubs—producing, storing, and trading alternative fuels for fuel cells and other power-generation devices.” By doing so, he says, ports could turn a profit while also breaking the stalemate and contributing to global decarbonization efforts.

Although concerns about nitrogen oxide emissions remain, companies including the partnership that is retrofitting the Viking Energyare reportedly designing post-combustion systems, analogous to the catalytic converters in automobile exhaust systems, to filter out harmful byproducts. A technique called selective catalytic reduction converts nitrogen oxides into nitrogen and water. Ammonia slip catalysts capture unburned ammonia and break it down into the same two inert products.