Zero-Emissions Trucking: Saved by Ammonia?

Momentum. As much as anything else, that’’s what the idea of zero-emission trucks has going for it. Sometimes it seems like the bandwagon to beat all bandwagons. But there may be options you didn’t know about.

Like ammonia.

Yep, that acrid, distinctly unpleasant smell of ammonia could actually be coming to save our tiny planet from environmental devastation. A long shot, maybe, but it’s definitely being explored.

Ammonia is one of the most produced industrial chemicals in the world, somewhere between 70% and 85% of it used to make agricultural fertilizer (nobody seems to agree on that figure). Sometimes it’s directly injected in pure form into the ground to increase yields of crops such as corn and wheat. Then there’s refrigeration. And lots of it, heavily diluted with water, is found in ordinary household cleansers.

Ammonia has dozens of other legitimate industrial applications — and it may well fit one of our own needs in trucking quite well. Partly because it’s free of carbon, but perhaps also because it’s an efficient carrier of hydrogen.

Sometime in the not-too-far future, you won’t be able to buy a new diesel-fueled truck. Maybe as soon as 2035. And I’d wager serious money that some jurisdictions will ban all such trucks from entering their territory. Some cities will do the same; quite a few in Europe and elsewhere already have, like Paris, Madrid, Athens, and Mexico City.

But you may not be limited to battery-electric or conventional hydrogen fuel cell vehicles as the only alternatives. Ammonia could do the job in a couple of ways. Possibly as a liquid fuel injected into internal-combustion engines, or perhaps as a carrier of hydrogen for a fuel cell. Its chemical makeup is three hydrogen atoms and one nitrogen, its official moniker NH_3.

Among others, a small start-up company based in Brooklyn, New York, with significant operations in Norway within the marine shipping industry, is showing us how.

An Ammonia-Powered Truck?

In mid-January, Amogy Inc. announced the successful testing of what it said is the first-ever ammonia-powered, zero-emission semi-truck.

After integrating its technology into a 5kW drone in July 2021 and a 100kW John Deere farm tractor last May, the company scaled its ammonia-to-power technology up to 300 kW. Following an eight-minute-long fueling, a Freightliner Cascadia tractor with 900 kWh of total stored net electric energy onboard was tested for several hours on the campus of Stony Brook University on Long Island, New York. Full-scale testing on a proper test track is set to follow quickly.

“Unlocking ammonia’s potential, Amogy’s proprietary technology enables the on-board cracking of ammonia into hydrogen, which is then sent directly into a fuel cell to power the vehicle,” the company explains. “Liquid ammonia has an energy density that is approximately three times greater than compressed hydrogen and it requires significantly less energy, making it cost-effective to store and transport.

“Ammonia presents a clear path to a zero-carbon fuel value chain across all heavy-duty transportation sectors thanks to existing transportation and storage infrastructure,” the company says. A global commodity, 200 million tons of ammonia are already produced and transported each year, making it an ideal and accessible alternative fuel.

“Beyond its incredible energy-density and liquid phase at an ambient temperature, ammonia is an optimal fuel to achieve rapid decarbonization of heavy transportation because it is available globally with… infrastructure already in place,” said Seonghoon Woo, CEO at Amogy. “In the near future, we look forward to further scaling and tackling other hard-to-abate sectors, such as global shipping.”

Another Way to Use Ammonia in Trucks

A company based in Mississauga, Ontario, Hydrofuel Canada, has another way to use ammonia — by directly injecting it into your internal combustion engine along with a small amount of diesel or biodiesel to help with combustion. It demands some smallish modifications to the engine to make it a multi-fuel motor, but it’s said to be an easy retrofit.

There was supposed to be a test running in two heavy-duty tractors in fleet service a couple of years back, but various challenges associated with the Covid pandemic stopped that in its tracks. The hope is to do that test this year. Company chairman Greg Vezina says that he’s even more hopeful of success in stationary engines and gensets, and the plan is to test a couple of those at the same Toronto fleet.

According to Vezina, ammonia “is the most environmentally benign fuel when compared with gasoline, gaseous or liquid hydrogen, liquefied petroleum gas, diesel, compressed natural gas, electric [where electricity is created from fossil fuels], and hybrid electric vehicles.”

None of this is altogether new. In fact, such uses of ammonia go back to the 1800s. For instance, an ammonia-fueled streetcar in New Orleans was tried in 1871. And during World War II, it was relatively common to see liquid ammonia replacing hard-to-find diesel or gasoline in all manner of vehicles in Europe.

There are presently many projects across the world aimed at using ammonia as a carbon-free fuel, especially in power generation and other off-grid applications, as well as internal combustion engines.

Ammonia and Hydrogen Fuel Cells

In the larger picture, the most important role for ammonia will likely be its use, not as a zero-carbon fuel, but as an effective energy carrier for hydrogen to power fuel cells. Chemists and others say it will create the road to the hydrogen economy.

Ammonia smells awful and is dangerously caustic, but compared to hydrogen, its energy density by volume is nearly double. It’s also easier to ship, store, and distribute using existing infrastructure. And that resolves one of the greatest barriers to the adoption of hydrogen, namely the cost of storage and transportation.

The key here is that while hydrogen needs to be cryogenically frozen to -253 degrees C (that’s 423 degrees below zero Fahrenheit), ammonia only needs to be cooled to -33°C (about 37 below zero F) to remain in a liquid state. Liquified ammonia contains nearly 50% more hydrogen by volume than liquid hydrogen itself and can be “cracked” using inexpensive catalysts to provide hydrogen.

It’s all somewhat ironic and circular. We’re going to make hydrogen, extract ammonia from it, then store and transport that ammonia to wherever it’s needed, and finally drag the hydrogen back out to use in a fuel cell.

"You can store it, ship it, burn it, and convert it back into hydrogen and nitrogen,” says Tim Hughes, an energy storage researcher with manufacturing giant Siemens in Oxford, U.K. "In many ways, it's ideal."

But of course, we want “green” ammonia to make green hydrogen, which isn’t possible in the usual production method — which is to strip hydrogen from natural gas using steam and then combine that hydrogen with nitrogen from the air at high pressure and extremely high temperatures. That’s the Haber-Bosch process, invented in the early 1900s by a couple of smart Germans and in use ever since. Problem is, it’s dirty, spewing two tons of CO2 into the atmosphere for every ton of ammonia made.

So, we must take natural gas out of the equation and instead make hydrogen by electrolysis using electricity sourced from renewables — and then make ammonia out of it. Projects from Canada to Australia are being built as we speak to accomplish this. The biggest is in Saudi Arabia, which will make a million tons of ammonia a year after it comes on stream in 2025. A more modest green ammonia plant in Louisiana is expected to produce 20,000 tons annually this year.

While pure hydrogen has been seen by many as the fuel of the future, it looks like ammonia is the better route to the same place.

“It ticks all the boxes,” says Jimmy Faria, a chemical engineer at the University of Twente in the Netherlands.

Does any of this mean anything to folks running trucks today? Maybe, if you want to try a multi-fuel engine retrofit. But really, the significance of ammonia here is that the day you can buy a truck powered by a hydrogen fuel cell is closer, at a lower cost. And unless battery technology develops such that you get the range you may need, you may eventually want that truck.