It’s funny. We’ve been working with biofuels for decades and are familiar with biodiesel, ethanol, biobutanol, syngas etc. Now, late in the day and basically from out of left field, we have another equally fascinating biofuel story to add. Ammonia. This organic chemical (NH3) is well known and understood. It is used in fertilizer, dyes, explosives, plastics, refrigerants, textiles, water purification, pesticides, as a nutritional supplement and in pharmaceuticals. It is less known as a combustion engine fuel. This comes just as the possibility of a transition from polluting grey ammonia to carbon free green ammonia emerges. Farms in the future may be able to be 100% sustainable by using green ammonia as a fertilizer and it could also be cheaper than today’s huge market in fossil-fuel sourced, grey ammonia.
Ammonia is a toxic gas at room temperature and liquifies under slight pressure. It has a distinct, strong, pungent odor and is corrosive to alkaline metals such as aluminum, zinc and magnesium. It is just over half as dense as air, in which it will quickly rise and disperse. Its very useful to store fuels as liquids to obtain the highest energy density and transportation convenience. Ammonia transitions from gas to liquid (boiling point) at just -33.33 °C. In contrast, the natural gas boiling point is all the way down at -160 °C and hydrogen is even more challenging at -253 °C. Ammonia is much easier to maintain in storage tanks and has no flash point so a naked flame will not ignite it.
Ammonia’s story is nothing short of a thriller, complete with mad scientists, Nobel Prizes, romance, wars, famine and huge challenges that even nature had difficulty solving. Plants need nitrogen but not all plants can incorporate it even though 78% of the atmosphere is nitrogen gas. All plants, whether they fix nitrogen themselves, as some do, or find it in the soil, use nitrates to make proteins including essential molecules like DNA. Crop plant roots quickly exhaust the nitrates present in soils. To compensate for depleted soils, farmers in the late 19th Century had been employing increasing amounts of guano fertilizer. Guano is formed of bird and bat excrement that accumulated, undisturbed, on remote islands for thousands of years. The Industrial Revolution had significantly improved living conditions but the increasing demand for food caused farmers to increase agricultural yields with guano fertilizer. New agricultural production in the fresh and fertile soils of the expansive European, Russian and US plains helped matters, but by the end of the century supplies of guano were running out and the human population had grown to 1.6 billion.
In the autumn of 1898 the incoming president of the British Academy of Sciences, Sir William Crookes, gave an alarmist inaugural speech in which he explained that unless a replacement for guano was found, there would be widespread human starvation. His message reverberated widely in the media. He even stated, specifically and presciently, in his speech that, “…it is the chemist who must come to the rescue”. Was humanity doomed?
Sure enough, in 1908, a German chemist, Fritz Haber discovered a way to produce ammonia using pressure and heat. He initially used expensive osmium as a catalyst. Another German scientist, Carl Bosch, scaled production up to 20 tons per day by 1913, using common iron as the catalyst making the process much more economical. Both scientists were awarded the Nobel Prize for Chemistry in 1918. However, within the euphoria was camouflaged another, more sinister need for nitrates.
Smoky, expensive gunpowder had been replaced by nitrate compounds by 1846 making ammunition propellant smokeless and 6 times more powerful. The British Government realized that nitrates were a strategic necessity for production of ammunition and explosives in a period of growing geopolitical uncertainty. The British expected Germany would run out of munitions if Great Britain controlled the nitrate supply. Instead, the surprise development of the Haber Bosch process made nitrates from atmospheric nitrogen and hydrogen from plentiful German coal. Haber and Bosch enabled the First World War to continue for 5 long, bloody years, and also enabled Germany to use poisonous chlorine gas in that war. Clara Immerwahr, Haber’s wife, also a chemist, fatally shot herself out of shame for her husband’s grisly contributions to the war. Despite helping Germany’s cause in the First World War, he was forced to flee Germany for the UK due to mounting antisemitism. Haber’s welcome in the UK was also strained by his First World War activities. He finally found a job in Israel but died from a heart-attack in a Swiss hotel on the way there.
The discovery of a way to make fertilizer created an industrial-scale activity and over the following century, the Haber Bosch process helped the human population continue to grow to its current level of 7.97 billion (August 2022). Humanity is now totally dependent on the continued production of ammonia. 80% of ammonia production is converted into fertilizer, and then to other nitrates and urea at further cost. As we have stated, ammonia is unusually productive with at least 13 other commercial uses. 50% of the nitrogen atoms in our bodies come from foods which used fertilizer from the Haber Bosch process. It should be mentioned that other fertilizing agents such as phosphates, along with selective planting and genetic selection, have also increased global crop yields.
Ammonia is made by squeezing together a single atom of nitrogen with three atoms of hydrogen. Traditionally the hydrogen came from and consumed a lot of fossil fuel. Indeed, 2% of all CO2 emissions can be traced to the Haber Bosch process, as well as emissions of nitrous oxides (N2O) and methane. 3.16 tons of CO2 are emitted for every ton of grey ammonia currently produced. We are going to continue to need huge industrial scale amounts of ammonia. Pre-war Ukraine was the second largest producer of ammonia for fertilizer. The coincidence of war and a shortage of natural gas has increased the price of ammonia from $250 per ton in 2020 to $1,600 per ton by April of 2022.
Weekly ammonia prices from Jan 1, 2020, to April 29, 2022. Source: EIA.
The huge, destructive, global scale of grey ammonia production has focused attention on the possibility of generating green ammonia instead. Lower carbon emissions ammonia is widely demanded and there have been many efforts to manufacture it. Indeed, until the wide availability of natural gas, which was a significantly cheaper feedstock for ammonia production, the hydrogen part of the equation was initially sourced by using hydropower to electrolyze water. The problem there was that you were still stuck with the same Haber Bosch process once you have your hydrogen. Although there has been a lot of effort made to find an alternative to Haber Bosch (especially in Australia), almost all of the many green ammonia initiatives basically replace fossil fuel energy for sustainable energy on the front end and find the hydrogen from electrolyzing water. This means that the resulting product, like other green fuels, is often more expensive than grey ammonia. A large amount of energy is still needed to combine the nitrogen with the hydrogen using high temperatures and high pressure. New methods necessitate trial and error, but there are signs that emerging technological approaches can scale production of green ammonia at significant cost reduction. This realistic, pragmatic vision suggests that farmers can now use green ammonia to replace diesel fuel for farm vehicles and electrical generation and finally for fertilizer itself, all at a lower cost and with a zero emissions footprint.
The ammonia market is huge and the need for a sustainable green alternative is already acting as an accelerant to increasing green ammonia activity. While it will take a bit of time for the capacity of green ammonia to build, there is no doubt that the ammonia market is being disrupted right now!