Finding The Way To An Ammonia Economy
As renewable energies progress, some limitations are becoming clearer. Renewables’ intermittency requires energy storage, which could be batteries, as we explored in our article “The Future Of Energy Storage—Utility-Scale Batteries Tech.”
However, some forms of energy consumption are very resistant to electrification. For example, long-distance naval shipping, or air freight.
For these applications, dense liquid fuel is preferable and probably the most likely option for air travel. So to replace fossil fuels, ammonia has been considered as a solid alternative. Ammonia is also a key compound in the production of fertilizers and chemicals like explosives.
Currently, ammonia is responsible for 1.8% of global energy consumption and carbon emissions, and that’s before we try to use it for transportation. It is currently produced by burning methane, creating so-called gray ammonia. A better alternative would be so-called green ammonia, produced from renewable energy.
The issue is that, for now, green ammonia is much more expensive than oil-based fuels or gray ammonia. In large part, this is due to the fact that ammonia is produced by using hydrogen, which is itself expensive to produce by electrolysis.
Alternatives like lithium-mediated catalysis could be possible and cheaper, but maybe still not cheap enough.
But there might be an alternative to hydrogen, at least according to researchers at the Buffalo State University of New York and the University of Auckland (New Zealand). They recently published their findings on how to produce ammonia with plasma in the Journal of the American Chemical Society under the title “Controlling the Reaction Pathways of Mixed NOxHy Reactants in Plasma-Electrochemical Ammonia Synthesis”.
The Many Paths To Ammonia Production
Nitrogen (N2) is very abundant on Earth, making up 78% of the atmosphere. But to be useful for plants or as a chemical, we need it in the form of ammonia (NH3) or nitrate (NO3). Adding these hydrogen atoms to the nitrogen atom is a very energy-intensive process.
One way to do it is through special bacteria, called nitrogen-fixing bacteria. This is one of the largest sources of natural nitrogen (100–300 Teragrams of nitrogen per year globally), but generally insufficient for intensive agriculture.
As mentioned, another is using hydrogen (H2), but producing green hydrogen is expensive.
There is, however, a third way to produce ammonia, one that occurs sometime in nature. When lightning strikes, the intensity of the electric current breaks up the N2, creating several forms of nitrogen oxides.
Source: Britannica
In nature, these nitrogen oxides are then converted into ammonia by bacteria. This is all but a small portion of the natural ammonia production, in the range of 3-10 teragrams. This is something that could be replicated artificially, bypassing the need for hydrogen entirely.
Man-Made Plasma Replacing Lightning
The researchers injected air into a plasma reactor, a container with an electrode and a glass tube. The plasma discharges replicate the effect of lightning, creating a complex mix of nitrogen oxides in the reaction chamber.
Source: ACS Publication
These mixed gases are then sent to a catalytic reactor containing a copper-palladium alloy structured like a foam. This catalyst is in charge of first absorbing the nitrogen oxides from the residual air and then replacing the bacteria that, in nature, would have converted the oxides into ammonia.
Fine-Tuning The Catalysis
The second step of turning nitrogen oxides into ammonia is all but simple.
“When plasma energy or a lightning strike activates nitrogen, you generate a soup of nitrogen oxide compounds. To simultaneously convert, in our case, up to eight different chemical compounds into ammonia is incredibly difficult.”
Xiaoli Ge – Postdoctoral researcher at the University at Buffalo
This means it is not just 8 chemical reactions that are needed to turn oxides into ammonia, but actually many more intermediate steps, each potentially causing a chokepoint and reducing the overall efficiency of the system.
It is also a problem as nitrogen oxides are somewhat polluting, and any large production of ammonia with this method needs to have as little residual nitrogen oxides as possible.
So, the researchers had to create a series of bimetallic catalysts that were then fine-tuned to target “the optimal adsorption and conversion of the limiting intermediate in the NOx-to-NH3 pathway”.
They used a mathematical process called graph theory to map out all the different reaction paths. This way, they could identify from the beginning where the bottlenecks were and how to improve the conversion efficiency.
Doing so, they discovered that most nitrogen oxide compounds have to cycle through nitric oxide or amine as an intermediate step before becoming ammonia. So, they made a catalyst that binds favorably with those two compounds.
Scaling-Up
The finalized design achieved an ammonia production rate of 81.2 mg/h/cm2. The plasma chamber and copper-palladium catalyst were stable after more than 1,000 hours of runtime at an applied current of 2 amperes.
The research team is now investigating the next step for scaling up their experimental reactor, considering both a startup and licensing the technology to industrial partners. Buffalo University has also filed a patent application for the reactor.
Contrary to the current fossil-fuel-based production, this plasma-based ammonia production would present a few key advantages:
- Being entirely driven by electricity for plasma generation, it can be powered by 100% green energy.
- It could be incorporated in a medium-sized container and connected to solar panels, not requiring the massive scale of current ammonia plants.
- Further progress in catalyst science could help improve the costs of the system, as well as continuously decreasing costs of green energy, especially solar.
“You can imagine our reactors in something like a medium-sized shipping container with solar panels on the roof. This can then be placed anywhere in the world and generate ammonia on demand for that region.
That’s a very exciting advantage of our system, and it will allow us to produce ammonia for underdeveloped region with limited access to the Haber-Bosch process.”
Chris Li – Assistant professor of chemistry
Potentially, investigating other options not requiring expensive palladium, like a bioreactor containing the right bacteria, could also be an option for further development, but it might be difficult to scale up to the volume needed for ammonia to become a global fuel source.
Investing In Ammonia
We already covered a few green ammonia investment possibilities in previous articles, as well as the science behind it, notably “The Other Hydrogen Fuel – Top 5 Green Ammonia Stocks” and “Decarbonizing Global Shipping Lanes through Green Ammonia”.
However, regarding the emergence of this new plasma-based ammonia production process, a more relevant stock to invest in could be a palladium miner, as any scale-up production would need a massive volume of the catalyst used by the researchers.
Palladium was mostly produced in 2023 by Russia and South Africa, followed by Canada and Zimbabwe.
Source: Statista
And, of course, direct investment in palladium, in the form of coins or metal bars, is also possible from precious metal bullion sellers.
Source: US State Mint
Palladium prices have been very volatile in the past years, with a massive price surge as a consequence of the Ukraine war and the importance of Russia’s supply in this market. They have since fallen back down.
Source: Investing.com
1. Sibanye Stillwater Limited
By far the largest palladium & platinum-focused company, Sibanye Stillwater, is a leader in its industry. It is also the world’s largest rhodium producer.
Sibanye Stillwater Limited (SBSW -0.87%)
Besides these metals, it is also a producer of other platinum group metals, such as iridium, and ruthenium. In large part, this is because the metals of the Platinum Metal Group (PGM) tend to be found and mined together in the same ores.
Stillwater
In September 2024, Sibanye Stillwater announced that it would restructure its Montana Stillwater mine, cutting this mine’s output by 45% to reduce costs. The mine, which contains more palladium than platinum, has suffered from low prices of palladium.
This led to a massive $435M impairment charge, causing the company to register a loss in H1 2024.
This would also make it a valuable dormant asset in case palladium becomes an important “energy metal” to mass produce ammonia with plasma.
It is also worth noting that current prices are barely enough to cover production costs for most platinum-rich regions, making it a bottom plateau for the industry before mine closure.
Source: Sibanye Stillwater
Sibanye Stillwater is currently diversifying from a pure PGM miner to enter the gold and battery metal markets, notably for a lithium mining project in Finland.
Source: Sibanye Stillwater
The company also has a presence in uranium mining with the Beisa uranium project in South Africa. It recently sold it to Neo Energy in exchange for a 40% equity stake in Neo Energy, as well as royalties on all uranium sold, with payments capped at $5 per pound, depending on the spot uranium price.
“The sale of Beatrix 4 shaft and the Beisa uranium project is in line with Sibanye-Stillwater’s strategy to unlock value from our uranium assets.”
Neal Froneman – Sibanye-Stillwater chief executive
Overall, Sibanye-Stillwater is the world’s largest international PGM mining company, and its shareholders would benefit greatly from some of the energy sector turning to either hydrogen or ammonia for transportation fuel. This is because almost all possible technologies in this segment require either platinum, palladium, or rhodium for hydrogen electrolysis, ammonia production, or fuel cells, due to the fundamental physics of catalysis hydrogen reactions needing these special metals.
It is also expanding in low-carbon energy, from lithium to uranium, making it one of the mining companies the most likely to benefit from the turn toward a green economy powered by renewables and hydrogen/ammonia.
