A commonly asked question with respect to climate change: What should we do?

A better question to ask: What can we do?

All proposed solutions face challenges — economic, technical, operational, political, and cultural. These challenges should not limit ambition or prevent action. Still, making progress requires respecting these challenges to surmount them.

So what’s possible right now is a good place to start.

One thing governments can do is buy clean. In fact, governments have extraordinary powers to make change through purchasing. Famously, Winston Churchill use procurement to convert the British navy to run on oil as a way to diversity in fuel suppliers and enhance national security. The U.S. govt. largely fed and nurtured both Silicon Valley and SpaceX, purchasing semiconductors and satellite launching contracts to assure supply.

In that spirit of action and progress, my modest proposal: the U.S. Coast Guard can be the cleanest in the world — time for the ammonia fleet.

Really. Ammonia. The entire Coast Guard could run 100% on fuel produced in the US with zero percent carbon. Ships could operate with current performance, transitioning from the current internal combustion engines to fuel cells and operate with zero local pollution from soot, ozone, nitrous oxides, or sulfur.

A bit of background on ammonia — one nitrogen and three hydrogens. Most folks know it as a cleaning fluid, but ammonia’s big market is as the primary ingredient of fertilizer. The world makes about 240 million tons/y of ammonia and ships it to over 120 ports around the world — mostly so humans can eat.

The shipping part is noteworthy because ammonia can also serve as a fuel. It can be blended into many existing combustion engines, including on ships, up to 50% today. Alternatively, it can flow through a fuel cell and generate electricity without combustion — the only products are electricity, water, and nitrogen gas.

As a fuel that’s shipped around the world, ammonia has attracted major interest from many companies and many nations — notably Japan, Korea, and Singapore. These three nations have established, as national policy, to buy ammonia to displace other carbon-intensive fuels, specifically coal, natural gas, and oil. These nations are driving the market by creating demand, with new bilateral agreements with supplier nations.

The decision by Japanese companies and policy makers to use low-carbon ammonia as a clean fuel has launched large projects around the world. Some of these are “green ammonia” projects fueled by solar and wind power electrolysis. The NEOM project in northwest Saudi Arabia and the goliath Australian project (Asian Renewable Energy Hub) plan to send their fuel to Japan. Other projects are “blue ammonia” made by new hydrogen and ammonia systems with integrated carbon capture. Saudi Arabia has already shipped blue ammonia to Japan, and Qatar, the UAE, and Oman have all said they plan to do the same.

Why should Japan have all the fun? I say the U.S. should purchase ammonia for domestic fuel use, specifically to clean up our ports and the Coast Guard — a vital military and law enforcement asset. The U.S. government could drive similar investments in clean supply and use, and use fuel cells to drive the ships already on the water. New low-carbon ammonia plants announced in the U.S. would proceed with an eye toward international markets — sales to Japan, Korea, and Europe — while serving domestic military, environmental, and security needs.

Of course, this also could provide climate benefits as well — if done correctly. Specifically, clean ammonia must be made without generating its own carbon pollution.

The main ingredient in ammonia is hydrogen. Today, hydrogen is chiefly made from natural gas or coal without carbon controls (“gray” hydrogen). This adds ~250 million tons of CO2 to the air and oceans every year. In short, ammonia today is not low-carbon.

It could be, though. Hydrogen (and ammonia) can be produced from clean sources of hydrogen (green, blue, and bio)* which would make ammonia a near-zero emission fuel. If made from green or biohydrogen, such ammonia would also be fossil-free fuel.

So why the Coast Guard? In short — duty cycles. Until low-carbon ammonia fueling centers are in ports around the world, ships powered by ammonia would need to return to the same port for fueling. Coast Guard ships largely remain within ~500 miles of their home ports and commonly return to the same ones, representing short-haul duty cycles.

The Coast Guard, although one of the five U.S. military branches, operates within the Department of Homeland security. This means that an ammonia fleet would start as a line item within the DHS budget. To avoid misspending, waste and poor outcomes, any program should begin as a set of pilots — a handful of ships in a handful of ports. Key ports, like Miami, San Francisco, Cape Cod, Honolulu, and Norfolk, could start with small fueling facilities and a range of vessels that represent the core Coast Guard operations.

Pilot programs would provide data and information on performance, cost, operations, and environmental issues. Projects could be done within the Justice40 framework, helping ensure that disadvantaged communities receive both economic and environmental benefits from the program. If the pilots prove successful, then slowly the fleet would migrate away from diesel and gasoline to ammonia, largely underway by 2030.

Some analysis would help, too. The Coast Guard certainly understands it job and energy needs better than I do! If asked by Congress or by Administration leadership, they could assess what fraction of the fleet could function soon on ammonia and what locations might best serve the nation’s needs in terms of the performance of their duties and the opportunity to decarbonize.

The military has done this before and at scale. One very similar example was the use of biofuels for military jets. Congress mandated military biofuel procurement, which led to production of biorefineries as well as testing programs to confirm fuel and fighter performance (no one wants to void the warranty on an F-14 or a Coast Guard Cutter).

The benefits would be real — reduced pollution in ports, reduced dependence on fossil fuels, reduced greenhouse gas emissions. The risks would be small, since ammonia production already exists in the U.S. in large volume and is growing.

The cleanest fleet on earth is not just possible, it’s inevitable and can start today. The costs are modest and the opportunity grand. Let’s keep our territorial waters clean the same way we keep our kitchen floors clean — with ammonia.

* If you want to know more about clean hydrogen production, there are many good references today. These include reports on blue hydrogen (here and here), on green hydrogen (there and there) and on the potential for low-carbon bio-hydrogen (this and that).

This article is also published on the author's blog. Energy Voices is a democratic space presenting the thoughts and opinions of leading Energy & Sustainability writers, their opinions do not necessarily represent those of illuminem.