Ammonia, the substance that changed the world (translated by Mark Theobald)
Ammonia, the substance that changed the world
The production of NH3, the base of agriculture and also warfare, reaches its centenary.
Neither electricity nor computing; not even television. What really changed the course of the 20th century was ammonia. This is the declaration of a group of scientists that are celebrating the centenary of the synthesis of ammonia, a compound with 3 atoms of hydrogen and one of nitrogen. As a fertiliser ammonia has sustained food production for billions of people; as an explosive it has resulted in the death of 150 million.
On 13th October 1908, the German chemist Fritz Haber filed the patent for ammonia. He had managed to solidify nitrogen in a useful and stable form for the first time. Scientists knew that nitrogen was a basic nutrient for plants but its gaseous form (that makes up 78% of the atmosphere) made it difficult to use. At the start of the last century the only solid natural forms of nitrogen were Peruvian guano and Chilean saltpetre or nitrate. However, it's availability was insufficient to satisfy the demands of modern agriculture.
What Haber patented was the process of obtaining NH3 by combining hydrogen and nitrogen a high temperature and pressure in the presence of a catalyst like iron oxide. The following industrial application of the process by Carl Bosch permitted the agricultural independence of Germany when, during the First World War, the allies blocked supplies of organic nitrate.
The two chemists received Nobel prizes for their Haber-Bosch process. Today 150 million metric tonnes are produced; 80% of which is used in agriculture.
The latest issue of the journal Nature Geoscience includes an article entitled "How 100 years of ammonia synthesis changed the world" Its authors provide some facts that highlight the importance of ammonia.
Its appearance provoked a dramatic increase in world agricultural production. It is estimated that the number of humans supported by each hectare of productive land has gone from 1.9 in 1908 to 4.3 a century later. Nitrogen fertilisers are responsible for feeding 48% of the current world population.
From life to death
In reality the application of ammonia awoke in the German industrialists an interest much greater than its use as a fertiliser even before the outbreak of hostilities in July 1914. The supply blockage by the allied forces did nothing but accelerate the military applications of ammonia. Thanks to the Haber-Bosch process, ammonia is oxidised and converted to nitric acid, the basis of explosives such as ammonium nitrate, nitro-glycerine and trinitrotoluene (TNT).
Germany, a country central and isolated, could wage war for much longer thanks to the ammonia that helped sustain its population as well as its bullets, missiles and bombs of its soldiers. Since then ammonia has been the basic element of munitions. The authors affirm that reactive nitrogen is directly related to the deaths of between 100 and 150 million people during the wars of the 20th century.
Long list of applications
The list of applications of ammonia is enormous: dyes for textiles, new materials such as nylon, cattle feed, the first refrigerators and air conditioning units, paints, cleaning products, mineral extraction... None of this would have been possible, at least as we know it, without ammonia. As put by the authors looking at the 20th century "Has any other patent changed the world as much as that filed by Fritz Haber 100 years ago?"
Fritz Haber, the father of chemical warfare
In his acceptance speech at the Swiss Nobel Academy in June 1920, Fritz Haber (1868-1934) avoided the role of ammonia in warfare and instead concentrated on the importance it had for agriculture and food production. Neither did he touch on the more delicate subject of its role in chemical warfare.
On 22nd April 1915 the 2nd battle of Ypres took place in the Belgian fields of Flanders. French, British and Belgian soldiers trapped in their trenches saw themselves surrounded by a cloud of 150 tonnes of chlorine dioxide. Those that didn't die fled terrified.
Haber, according to his biography, said on one occasion that "if you want to win the war, then you have use chemical warfare". Following this apparent coldness of the German chemist he defended himself by saying that chemical agents could shorten the conflict, therefore reducing the number of deaths (an argument later revived by the defendants of the atomic bomb).
The chemist of Jewish descent felt patriotic. On one occasion he said that "a scientist has a duty to his country in times of war and to all humanity in times of peace." He was directly involved in the design, creation and delivery of toxic gases. As Captain of the Wehrmacht he was personally responsible for the attacks and chemical defence against the French gases.
Following the war, Haber returned as director of the Institute of Physics and Electrochemistry of Berlin-Dahlem. Recognised by everyone he dedicated these years to raising German science and alleviating the economic problems of his country's defeated people. He developed a method for detecting gases in mines. However the majority of his time until 1926 was dedicated to looking for gold in the sea. With his knowledge of pressure and catalytic processes, he strongly believed that this precious metal could be obtained from the sea in order to pay his government's war debts but his crazy dream was a failure.
In one of the most dramatic and cruel paradoxes, a group of researchers under his supervision created Zyklon B, an insecticide based on cyanide. The poison was used years later by the Nazis in the concentration camps. Amongst the victims were some of his relatives.
The blind faith in science of Haber was apparent in his inauguration speech at the German-Japanese Institute where he said "Science determines the measure of man's prosperity; its crop is the seed of wellbeing of future generations".
With the rise to power of Hitler not even Haber , with what he had given to his country, was safe. The chemist was forced to leave his institute and abandon Germany in 1933. One year later he died from a heart attack in the Swiss city of Basel or as the Nobel Foundation biography puts it "his heart broke from the rejection by the Germany he had served so much".
Environmental impact
Only 17% of the ammonia used as fertiliser is consumed by humans in food. The rest ends up in the soil or the atmosphere. According to the article in Nature Geosciences, emissions in absence of humans are 0.5 kilograms per hectare per year. Modern agriculture has multiplied this value by 20, which has had he effect of altering he natural nitrogen cycle, although it's global impact is not well known.
There are two problems directly related to ammonia. One is the Eutrophication of waters. The nitrates that end up in the rivers and seas, the algae and bacteria feast on the excess nutrients using up the oxygen needed by other species. In addition, reactive nitrogen is altering the atmospheric balance, increasing tropospheric ozone whilst reducing it in the stratosphere. On the other hand ammonia has a positive effect on the capture of CO2 by forests due to the increased presence of nitrogen in the air.