One thing we have learnt this week- the Haber process is 100 years old

The Haber process is 100 years old this year.  Haber its inventer was both a controversial and contradictory figure.  A chemist, his most famous contribution was to discover a means of removing nitrogen from the atmosphere and make it chemically available, although he worked on many areas of chemistry.  Born to a Jewish family in what was then Prussia and is now Poland, Haber converted to Lutheranism.  The irony was he became an ardent German nationalist who felt forced to leave Germany after Hitler’s rise  to power.  This nationalism had a darker side.  First, the process of making ammonia which he gave his name to (strictly speaking it is called the Haber-Bosch process since a scientist called Bosch made the Haber process a practical success) was discovered in 1913.  This allowed the Germans to –  at least as far as nitrates are concerned – overcome the British navel blockade.  Most nitrate was mined in Chile in those days and the Germans faced a shortage.   Ammonia can be made into nitrates.  Most explosives have nitrogen base.  So apart from its use in agriculture its reckoned that the Haber process lengthened the first world war by a year by its contribution to explosive manufacture.  Second, he worked on poison gases, (enthusiastically), being part of a unit that deployed the first use of chlorine gas on the Western front.  This led his first wife Clara (another chemist) to shoot herself and also his son by his first marriage commit suicide many years later.  In what has to be one of the most controversial Nobel prizes ever, he was awarded it in 1918 for the Haber process.  Most of the allies boycotted the award ceremony which was held in 1919.

The Nobel prize was controversial but you can see why they awarded it. It may lead to violence today as well as then (unfortunately fertilizer makes a crude but effective explosive which is still used by terrorist groups) but it fundamentally changed modern agriculture.  Nitrogen in the atmosphere exists as molecule made of two atoms of nitrogen joined by a triple bond.  This triple bond makes the nitrogen molecule very stable.  Only some bacteria, plants (legumes) in a relationship with some bacteria and lightening can break this bond in nature.  Haber discovered that by using high temperatures and transition metal catalyst (usually iron) the nitrogen triple bond can be broken and made to combine with hydrogen to make ammonia as shown below.

The chmical basis of the Haber processThe irony as far as agriculture is this has been both very bad and very good.  Its undoubtedly kept literally billions of us alive.  The “green revolution” which allowed growing global population to be fed, was only possible after the second world war in part due to nitrogen based fertilizers.  However,  the environmental effects have been very high.  Fertilizer tends to be added in excess and tends to end of in water courses.  It effects plants, animals and leads to the formation of algae and has effects on our climate.  Excessive use has altered the chemistry of soil making it almost dead in terms of micro-organisms, ironically making the use of fertilizers even more necessary.  Nitrates if ingested in excessive amounts by humans react with organic compounds in our stomachs forming nitrosamines which are carcinogenic.

However, one of the biggest problems with fertilizer isn’t often talked about.  That is its fossil fuel dependency.  Hydrogen has to be made, since little is present in nature.  Its made from natural gas by means a reaction called the shift reaction.  The Haber process also takes a lot of heat and therefore energy to carry out.  All in all something like 1-5% of the worlds natural gas to make the fertilizer we need worldwide.  This has led to use been horribly dependent on a declining resource.  As we wrote in our book

Sustained high prices or actual shortages of fertiliser would inevitably lead to a significant drop in food production. When this scenario was outlined to a group of farmers here in the UK, one succinct response was, ‘If they can’t give us fertiliser, we can’t give them food.’”

There are some solutions as we outline in our book, but its not going to be easy to replace the Haber process.

Haber left Germany resigning as the Nazis gained control in disgust at their treatment of his fellow Jewish academics.  He fled to the UK but died in Basel in 1934.  His son by his second marriage also fled to the UK and later wrote a well respected  book on chemical warfare.

Neil

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