TOKYO - Ammonia, commonly associated with its pungent odor and its presence in urine, is gaining recognition as one of humanity's most important inventions and a potential foundation for a new energy system that could reduce the world's dependence on oil.
A ranking of innovations that shaped human history, published by the Nikkei in May, placed ammonia first, ahead of vaccines in second place and the steam engine in third.
The result may appear surprising, but ammonia is an indispensable raw material for nitrogen fertilizer. Its artificial production enabled nitrogen in the atmosphere to be converted into inexpensive fertilizer, dramatically increasing agricultural output and helping avert severe food shortages as the global population surged from the late 19th century into the 20th century.
Ammonia is now attracting attention for another reason. As tensions in the Middle East heighten concerns over energy supplies, researchers and companies are studying whether the chemical could serve as an alternative energy source to petroleum.
Hitoshi Nishibayashi, a professor at the University of Tokyo's Graduate School of Engineering, is leading research into a new method of synthesizing ammonia. His team has developed an approach that could overturn a production system used for more than a century and potentially address one of ammonia's greatest weaknesses: the large volume of carbon dioxide traditionally emitted during its manufacture.
Ammonia is far more deeply embedded in modern life than its public image suggests. In addition to fertilizer, nitrogen derived from ammonia is used in medicines, nylon, clothing and a wide range of industrial products.
Its most important contribution, however, is food production.
"Ammonia is actually one of the major sources of the material that makes up the human body," Nishibayashi said, explaining that nitrogen fertilizer supports crops, which in turn provide the amino acids, proteins and nucleic acids required for human life.
Artificial ammonia synthesis made it possible to transform nitrogen from the air into fertilizer at low cost. This allowed farmers to produce crops on a scale large enough to sustain a rapidly growing global population, making ammonia central to the modern food supply.
Nitrogen is essential to both plants and animals, but obtaining it is difficult despite its abundance. Around 80% of Earth's atmosphere consists of nitrogen gas, yet most living organisms cannot use it directly.
The two nitrogen atoms in a nitrogen molecule are bound together extremely strongly, making the gas chemically unreactive. Humans inhale nitrogen with every breath, but the body cannot absorb it. The gas simply passes through and is exhaled without being used.
Plants face the same problem. Although they absorb carbon dioxide and release oxygen through photosynthesis, they cannot generally take nitrogen gas directly from the atmosphere. Nitrogen must therefore be supplied from another source.
Ammonia provides the bridge. Its simple structure consists of one nitrogen atom bonded to three hydrogen atoms, placing nitrogen into a form that plants can absorb. When ammonia-based fertilizer is added to soil, crops can take in the nitrogen and use it to grow.
The process forms part of a broader nitrogen cycle. Plants absorb nitrogen supplied through ammonia fertilizer. Humans then consume those plants or eat animals that have fed on them. Only through food does the nitrogen enter the human body and become amino acids, proteins, nucleic acids and other substances essential for sustaining life.
Although most organisms cannot directly use atmospheric nitrogen, certain exceptional microorganisms living in soil are capable of converting it into usable compounds, providing a natural counterpart to the industrial ammonia synthesis that transformed agriculture.
Source: テレ東BIZ
