Fiending for Nitrates
The Clandestine Chemistry of Fritz Haber
The German chemical industry was foundational in developing a myriad of chemical processes that quite literally revolutionised the world. The effects of this industry are invisible to us today, yet countless goods we enjoy are dependent on chemical innovations developed in Germany in the early 20th century.
One major breakthrough was the Haber-Bosch process, which produces nitrate from air and hydrogen. This process is absolutely foundational to the modern food system. Without the ability to fix nitrogen from the air, we would still rely solely on animal shit to fertilise crops. Vaclav Smil estimates that without the Haber process, we would need four times as much land to produce the same amount of food we do today—meaning that more than half of Earth’s dry land would have to be farmland (compared to just 15% today).
To put the importance of this process in perspective: as of 2018, the Haber-Bosch process consumes around 2% of the world’s total energy supply. Additionally, about 50% of the nitrogen in our bodies (originally from the plants we eat) comes from the Haber-Bosch process.
The development of this process was, in some ways, clandestine.
In 1914, Germany was at war and needed explosives, which depended on imported nitrates. British-imposed sea blockades cut off many essential raw materials, including saltpeter (NaNO3), a key nitrate for explosives, which was either mined in Chile or produced from guano (bird shit) found on tropical islands.
Germany desperately needed a homegrown, pure, source of Nitrates to stave of withdrawal.
Luckily Fritz Haber had been working on such a process. His method was purchased by the chemical company BASF, which assigned Carl Bosch the task of scaling it for industrial use. Together, they overcame the engineering challenges of high pressures and temperatures to produce the first ammonia reactors.
The process essentially burns methane gas in a large pressurised tube in the presence of a metal catalyst (initially osmium and uranium, later specialised iron catalysts). Hydrogen gas, liberated from methane, reacts with nitrogen gas to form ammonia, which can then be used to create other important nitrogen-based compounds like nitric acid, ammonium nitrate, and potassium nitrate.
N2 + 3H2 → 2NH3
While the synthetic production of ammonia was crucial for the German war effort, its impact extended far beyond. Today, synthetic ammonia is a vital raw material for millions of chemicals and is essential for fertilising the crops that sustain us.
It’s worth noting that Fritz Haber also pioneered chemical warfare, being the first to propose the use of chlorine gas in trench warfare. It’s ironic that bombs and nerve agents were the catalyst for technological discoveries that ultimately quadrupled the efficiency of agriculture. Complicated Guy.
— Errol Bloom
