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Great Expectations

The future of maritime fuel might just be under your sink

Most of us keep some form of household cleaner with ammonia sitting under our kitchen sinks. It waits there to help wipe up the next spill on our counter or remove dust on a mirror. Now the maritime industry is looking to use this common chemical to provide a sustainable energy solution for the future.

Ammonia has been gaining interest in recent years, not only as a fuel but also as means to store renewable energy. How can it fit into the IMO’s effort to limit global emissions from the maritime industry? Some believe the maritime industry is responsible for up to 2% of global carbon emissions every year, about the equivalent of Germany’s annual CO2 emissions. Finding a fuel source that not only cuts emissions but whose production is zero carbon is the best-case scenario. Hydrogen fuels cells could do just that, and ammonia shows potential as well.

First, a quick lesson in chemistry. Ammonia is a chemical made up of hydrogen and nitrogen, two naturally occurring elements that make up a large portion of our atmosphere. Ammonia’s combustion does not produce as much energy as gasoline or diesel but it has been proven to work as an alternative to both gas and diesel engines. It produces no harmful emissions—only hydrogen and nitrogen. It also has potential as a duel fuel alongside existing engine technologies.

Not only could ammonia function as an alternative to standard diesel and gas engines, making it relatively easy to implement, but it has secondary potential as a way to transport hydrogen for use in hydrogen fuel cells—another potential zero-emissions fuel source.

Hydrogen fuel cells create energy through a chemical process by which hydrogen gas and oxygen are combined to produce water. It’s far more efficient to store and transport liquid ammonia and then convert it to hydrogen than it is to compress, store, and transport hydrogen gas on its own. Ammonia’s energy density is close to twice liquid hydrogen’s.

Chemists to the rescue?

There is an inherent challenge to ammonia’s use as either a fuel or a hydrogen bank, however: ammonia is carbon intensive to produce. For ammonia to be considered a renewable energy, we must find a way to produce it using less energy. Fortunately, solutions are already on the horizon.

The hope is to produce green hydrogen from renewable sources and then use an electrochemical cell to combine that hydrogen and nitrogen from our atmosphere to form carbon free ammonia.

How could ammonia help the maritime industry go green?
  1. Relatively easy to convert for use with existing propulsion technology
  2. Global safety protocols for transport and storage have already been established for it
  3. A solution for stable hydrogen storage

Added bonus: ease of use

Assuming we can resolve the challenges surrounding ammonia production, implementation would be straightforward. Governments across the globe already have policies in place to regulate ammonia, which is not only common in households but is a key ingredient in fertilizers. As such, the movement and storage across our seas and in our ports would not be as challenging as with other fuel sources. The maritime industry could also take advantage of existing storage facilities for ammonia. As the network expands, convenient refueling for the shipping industry without large investments in new infrastructure, would only add to the advantage of this fuel.

Engineers are already starting to explore what ammonia powered ships would look like in real life. A North Sea supply vessel is scheduled to be refitted with carbon-free ammonia fuel cells in an EU funded project. The ship will help engineers understand what maintenance issues might arise with the goal of making it the first emission free super vessel. In China and in Korea, ammonia-fueled ships are already in production.

Ammonia is on the verge of becoming not just useful in the household but also in the new green economy. For the shipping industry it presents another option to come closer to what for some was once unimaginable: zero-emission shipping.

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