What is the Haber Bosch process? How important is it for the production of fertilizers to grow crops and feed the world? Why is it ecologically harmful and what other alternatives to the Haber Bosch process are out there? Let’s take a look.
What is the Haber Bosch Process?
The Haber-Bosch process is a technique that directly synthesizes ammonia by capturing the naturally-abundant nitrogen in the atmosphere and reacting it with hydrogen. According to a paper published in the Academic Press, ammonia is predominantly produced with the help of an iron catalyst at high very high temperatures and pressures (400–500°C, 15–20 MPa).
The Reactants of the Haber Bosch Process: Hydrogen and Nitrogen
Understanding how the reactants for the Haber Bosh process are obtained helps to further explain its ecological impact. Neither hydrogen or nitrogen exist alone in the universe, and obtaining them requires chemical manipulation, spending energy and using specific infrastructures and instruments.
How Hydrogen is Obtained for the Haber Bosh Process
Hydrogen was typically obtained via water hydrolysis, which consists of an electric current passing through water and separating oxygen from hydrogen. Nonetheless, today, steam methane reforming, in which methane is mixed with superheated steam, is the most common method due to its higher efficiency and being lower cost. In this way, hydrogen is commonly obtained via methane – a gas 84 times more potent than carbon dioxide according to the EDF.
Obtaining Nitrogen for the Haber Bosh Process
Nitrogen is obtained via the fractional distillation of the air which is liquefied (by cooling it to less than -200º Celcius) and goes over carbon, oxygen, and trace gas filtrations.
Why the Haber Bosh Process and the Need for Fertilizers
At the start of the 20th century the world population was growing exponentially, and so was life expectancy thanks to medical progress and technological developments. As a consequence, the world’s food supply could not keep up with the pace of the population’s increase, and scientists starting looking for ways to increase soil productivity.
Once scientists discovered the availability of the macro-nutrient nitrogen was limiting plant growth, farmers started spreading manure and animal waste on their soil to add nitrates to it. They also planted species that naturally help to fixate nitrogen in the soil such as soy or peanuts. Nonetheless, this method didn’t provide essential nitrates to increase plant growth and satisfy food demand.
In 1909, Haber figured out he could successfully fix atmospheric nitrogen by converting it into ammonia. A few years later, using Haber’s findings, Bosch developed the first industrial-scale application of the Haber Bosch process and nitrogen fertilizers started being produced on a large scale to boost crop growth and feed the world. Today, the Haber Bosch process is a key part of the conventional process of crop cultivation worldwide.
The Cons of the Haber Bosch Process
The Haber Bosch Process Leads to Eutrophication and Biodiversity Loss
The Haber Bosch Process has an ecological impact since soil fertilizers are easily soluble in water and as a consequence, easily transported from their designated soil in run-off waters. When they reach large water bodies a phenomenon known as eutrophication happens – the exponential, unnatural growth of algae that covers the surface of the water body, preventing sunlight to reach submerged species.
As a consequence, submerged organisms are unable to do photosynthesis and die. Moreover, algae also consume most of the water’s oxygen, often leading to fish dying from oxygen deprivation and to further impacts across the ecosystem due to their absence
High Energy Consumption Levels Are Used in the Haber Bosch Process
According to a paper published in CellPress and available in ScienceDirect, the production of ammonia via the Haber-Bosch process, “is the most energy-intensive commodity chemical, responsible for 1%–2% of global energy consumption and 1.44% of CO2 emissions”. According to
Professor Nishibayashi from the University of Tokyo’s Department of Systems Innovation, the Haber-Bosch process also consumes 3 to 5 percent of all the natural gas (a fossil fuel) produced.
The Haber Bosch Process and the Blue Baby Syndrome or Methaemoglobinemia
Methaemoglobinemia is described as the reduced ability of the blood to carry oxygen due to reduced levels of normal hemoglobin. One of the most common causes is nitrate in drinking water which can be originated by the leeching of nitrogen fertilizer into groundwater-drinking water.
Since it that particularly affects infants who show signs of blueness around the hands, mouth, and feet, the syndrome got to be known as the Blue Baby syndrome. According to the World Health Organization, some children may have trouble breathing as well as vomiting and diarrhea. In extreme cases, there is marked lethargy, an increase in the production of saliva, loss of consciousness, and convulsions, and even death.
SWAP: an Alternative to the Haber Bosch Process?
According to Professor Nishibayashi from the University of Tokyo, he and his team found, in a study published in Nature, a new way of synthesizing ammonia which is far cleaner, easier and cheaper than the Haber Bosch process. According to Nishibayashi, the “SWAP process creates ammonia at 300-500 times the rate of the Haber-Bosch process and at 90 percent efficiency,”.
Moreover, the Samarium-Water Ammonia Production (SWAP) process discovered requires only readily available lab equipment and recyclable chemicals, whereas the Haber-Bosch process requires large-scale industrial equipment.
Nishibayashi suggests that anyone with the proper source materials can perform SWAP on a table-top chemistry lab. From a sovereignty perspective, the SWAP technique looks promising in the sense that it can be used by those who would be otherwise stopped by the large capital investments required in the case of the HB process, decentralizing the process of ammonia production.