Ammonia stores hydrogen better than hydrogen itself in many ways, and it could help clean some tough industries that need high-density energy. The Brooklyn-based company Amogy has now presented the world’s first semi-trailer truck powered by ammonia.
As an energy carrier, ammonia has two major advantages over hydrogen. One is the fact that it is a liquid at ambient temperature and pressure, making it much easier to store, transport and handle. Hydrogen must either be highly compressed to around 700 bar or cryogenically cooled as a liquid to just 20.28 K (∆’252.87 °C; ∆’423.17 °F) – both are energy-intensive processes. The second is how much energy it carries: nearly three times that of hydrogen gas by volume, and more than 20 times that of today’s lithium batteries by weight.
It can be produced cleanly and used as a fuel in a variety of ways, many of which do not cause harmful or climate-relevant emissions. And although it has certain disadvantages, Green ammonia is seen as a promising clean fuel alternative for industries like marine, aerospace and other applications where batteries and hydrogen gas just can’t carry enough juice to get the job done.
Amogy was founded in 2020 to accelerate the development of green ammonia as an energy source for clean transportation. The company says it will fly a 5kW ammonia drone by July 2021, followed by fast a 100 kW ammonia tractor in May 2022.
Now it’s upscaled its ammonia powertrain to 300kW and is presenting it in what it claims is “the world’s first ammonia-powered, zero-emission semi-truck” — a 2018 Freightliner Cascadia Class 8 truck that’s been retrofitted with ammonia in the fuel system, slung under the cab and stacked behind it , which seemed to add little bulk to the standard truck.
It fills up in eight minutes to carry around 900kWh of “total net stored electric energy” — roughly the same amount of energy the Tesla Semi stores in its lithium battery packs. Amogy says its “zero-carbon power system…has 5 times the system-level energy density compared to lithium batteries,” so expect this cab to be significantly lighter than the Tesla.
The truck was built, filled and “tested for several hours on the Stony Brook University campus,” and is scheduled to undergo a full-scale, real-world performance evaluation at a test track later this month.
So how would we expect it to compare to the Tesla Semi? Is ammonia better than batteries for this type of heavy transport? That is very difficult to say; Amogy is not providing any performance or range estimates at this time.
We know there will be inefficiencies here that don’t apply to battery electric vehicles. Amogy’s powertrain features an ammonia cracker that converts the ammonia back into hydrogen. It then passes that hydrogen through a fuel cell to generate electrical energy and uses that energy to power electric motors.
So if Amogy’s “total net electrical energy stored” of 900kWh simply means there’s enough ammonia on board to theoretically store 900kWh, that doesn’t mean 900kWh reaches the engines. There will be losses in the on-board ammonia cracking reactors, further losses in purification stages that ensure the hydrogen is ready for use in the fuel cell, and further losses at the fuel cell stage.
We don’t know what technologies Amogy uses, or the efficiency factor in any of these phases. But we can try to guess. the Ammonia Energy Association cites a best-case ammonia cracking efficiency of 76%, but that’s probably on an industrial scale – we wouldn’t expect a cracking reactor that fits on a truck or tractor to operate that efficiently. However, if we use this number, around 684 kWh of energy will enter the fuel cell in the form of hydrogen. If we take a high-end estimate for PEM fuel cell efficiency of 65%, then 444.6 kWh of energy will get through to the motors. That’s a little less than half the original 900kWh, so the Amogy truck will go about half as far as the Tesla Semi in this optimistic scenario.
That doesn’t sound great. But on the other hand, you could easily increase the range by adding a few more ammonia tanks somewhere – and that’ll be a much less painful process than trying to increase the range of a lithium-battery-powered semi-truck. Also, this is a retrofit; When you design a new truck around the ammonia concept, you can do all sorts of things.
We’re excited to see how this machine performs. We’ve been mulling this over for a while now widely predicted lithium resource scarcity this is expected to occur over the next decade; There’s nowhere near enough lithium production to meet projected demand as the EV transition accelerates — let alone other battery-related metals.
Ammonia is an inefficient but highly compressed energy storage medium. It carries less than half the energy of diesel, but more than lithium or hydrogen, and it can be produced and used cleanly. It’s well understood in terms of storage, transportation and handling, and is already available in large quantities if you don’t mind working with dirty fuel to begin with. And as a readily available liquid fuel, it could well be relevant in freight transport.
Amogy next looks at the Navy. It says it will demonstrate a 1MW-scale ammonia-powered tug later this year, and it hopes to scale that up to over 10MW by 2025 to produce a powertrain relevant to container ships on transoceanic voyages is. Other ammonia fueled shipping projects are in the works; Australian mining company Fortescue, for example, says it will commission a 75-meter vessel sometime this year. However, this is expected to use an ammonia combustion powertrain instead of an electrical system powered by a fuel cell.
Check out a highly uninformative video of the Amogy truck below.
Amogy introduces the world’s first ammonia-powered semi-trailer