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story:New science, new materials, new power

scene:New chemicals: Ammonia

As the nineteenth century drew to a close, a number of prominent scientists expressed the belief that a rapidly increasing world population threatened to outrun the food supply. The most promising solution was to boost the world's crop yields with the increased use of fertilisers. Large quantities of ammonia, which is used in fertiliser production, were needed. The appalling prospect of a starving world underscored the opportunity to make huge financial gains should the problem of how to artificially synthesise ammonia be solved.

Ammonia contains nitrogen, which gives it the properties that promote plant growth. Traditionally farmers supplied that nitrogen by using manure to fertilise their crops. As the world's population grew and higher yields were needed, scientists began to search for new sources of fertiliser. Chile mined a seemingly plentiful supply of natural nitrates from the Atacama desert but there was concern that this resource would soon be depleted. Assured sources of cheap 'fixed' nitrogen — nitrogen combined with oxygen or hydrogen — were also needed by dye and explosives manufacturers.

Attracted by prospects of fame and profit a number of scientific institutions took a financial gamble and entered the race to synthesise ammonia. One of the most active competitors was BASF, the huge German chemical company that played an important role in the development of synthetic dyes.

Fritz Haber. picture zoom © Science Museum/Science & Society Picture Library

In 1909 Fritz Haber, a young physical chemist in Karlsruhe, Germany, struck the jackpot. He found a way to tap into the atmosphere's vast reservoir of nitrogen gas and combine it with hydrogen to form ammonia using enormous pressures, extremely high temperatures and a catalyst.

BASF promptly bought Haber's patents. But before his great discovery could be made profitable, one more step had to be completed: BASF had to turn his small-scale laboratory feat into a major industrial operation.

Carl Bosch. picture zoom © Science Museum/Science & Society Picture Library

Carl Bosch, a talented metallurgical engineer and BASF's future chairman, was given the task. He designed and built an industrial-size installation that could contain the great pressures and high temperatures required in Haber's process. Before long the scientific community was referring to the ‘Haber-Bosch process'.

The artificial fixation of nitrogen is considered one of the greatest innovations of the twentieth century and earned both men the acclaim of the international scientific community.

Haber's first sample of synthetic ammonia. picture zoom © Science Museum/Science & Society Picture Library

The ‘Haber-Bosch' process went on-stream in September 1913 and it is still the predominant method used. Many alternative techniques have been developed since but none have proved more effective.

The Oppau plant after the explosion of 1921. picture zoom © BASF Corporate Archives, Ludwigshafen/Rhein

The Haber-Bosch process gave farmers access to cheap nitrogenous fertilisers, enabling them to grow more crops. World production of cereals increased seven-fold during the twentieth century allowing humanity to survive a quadrupling of the population from 1.6 billion in 1900 to over 6 billion in 2000.

An advert for a more advanced type of fertiliser. picture zoom © BASF Corporate Archives, Ludwigshafen/Rhein

But the use of fertilisers has had a negative impact on the environment. Nitrates from fertilised soils end up in rivers, lakes and estuaries. They promote eutrophication whereby explosive growths of algae suffocate other species and create ‘dead zones'.

The production of synthetic ammonia enabled humanity to survive the population explosion but it also represents a major threat to many of the world's ecosystems.

Resource Descriptions

Fritz Haber.
Carl Bosch.
Haber's first sample of synthetic ammonia.
The Oppau plant after the explosion of 1921.
An advert for a more advanced type of fertiliser.
Scene  Rich Media