Greener alternatives and alterations
With all of the Haber Bosch reaction’s negatives all laid out, scientists still believe that there can be useful and safe ways to utilize its benefits. On newer horizons are some promising alterations to the Haber Bosch process that will make it a step forward for out society thought cleaner and more sustainable uses. At the very moment there is research being done to make the Haber Batch reaction happen under conditions where there is renewable energy being used to conduct it opposed to the intensive fossil fuels that drove it before. And in some cases like those listed on the Royal Society of Chemistry‘s article called, “Can sustainable ammonia synthesis pathways compete with fossil-fuel based Haber–Bosch processes?”, these reaction schemes can happen under less intense conditions meaning less of an energy input for the reaction. However these are in the extremely early experimental phases and will probably not be feasible on an industrial scale for some time now.
The Haber Bosch process is achievable without the use fossil fuels by deriving hydrogen needed to complete the reaction through water electrolysis instead of derivation from methane or coal gasification. This is also all the while using renewable energy for both the electrolysis and the energy to heat up the reaction of hydrogen and atmospheric nitrogen as well. Nothing has changed in the reaction accept for the sourcing of the energy and the sourcing of elemental Hydrogen.
2H2O (l) + Renewable Electricity –> 2H2 (g) + O2 (g)
The renewable energy will most likely be sourced from wind energy farms, hydroelectric dams, and solar fields and will be used to heat and pressurize the batch to its desired temperature and carry out the same chemical synthesis for ammonia as before.
N2(g) + 3H2(g) ⇌ 2NH3(g) ΔH<0
This reaction typically occurs at temperatures between 400-500 °C and pressures of 150-300 bar, usually with an iron-based catalyst. Below is a proper representation of the new life cycle of the Haber Bosch process provided by Springer.com
All of the issues previously mentioned about the environmental impacts are unfortunately still extremely prevalent with the continued use of ammonia based fertilizers for agricultural use however, there is other uses for the reaction product that can help mitigate environmental impact in other areas through mitigation of some greenhouse gasses that currently plague our atmosphere.
Now comes the question of what can the ammonia accomplish outside the realm of agriculture. This is where society can focus its efforts onto bio fuels, in other words carriers of hydrogen fuel cells for the future of long distance travel in the shipping industry. Miao Wang along with the others that wrote the article Can sustainable ammonia synthesis pathways compete with fossil-fuel based Haber–Bosch processes? all agree that ammonia is a perfect candidate to replace traditional fossil fuels because it is highly combustible, and because of its nature of composition it is a carbon-free molecule and burns without the byproduct of carbon dioxide. Because of this breakthrough in fuel sourcing, we can gear the automotive industry to be an ammonia based internal combustion fleet. An additional benefit to using this type of fuel is its storage capacity as a hydrogen cell. Ammonia is a molecule which carries three hydrogens in its chemical makeup which makes it a perfect liquid storage vessel for green hydrogen opposed to other gaseous methods.
https://pubs.rsc.org/en/content/articlelanding/2021/ee/
On top of this ambitious idea to convert over to a non-fossil fuel based economy, Dennison in Environmental risks of the third re-purposing of the Haber-Bosch reaction explains how the world economy is already structured to produce mass amounts of ammonia on a mass scale surpassing 163 million tons as N in 2022. So we already know the world is capable of meeting the industrial needs of supplying an ammonia based fuel system, what is holding us back from actually implementing this.
The only downside of this solution by switching to an ammonia based combustion driven network of transportation and alternative fuel use is its price. Sure most areas of the globe have the capacity and the infrastructure to support it, however because of how cheep it is for corporations and consumers to use conventional fossil fuels. The governments will have to step in and make sure that the right policy making goes into place like providing subsidies for green ammonia fuel systems can be implemented without having to bite too much of a monetary bullet with a high initial investment cost. Coupled with allowing for easy integration, if the world successfully transitions to an ammonia based fuel, the emission regulations will also have to adjust for the extra nitrous oxide in the atmosphere.
The so called “third repurposing” of the Haber Bosch reaction to stray away from using it for unnecessarily high crop yields and refocusing its efforts on the industry of clean energy and green hydrogen storage is definitely a step in the right direction. However, realistically this global effort will be a hard one to enact without the expressed interest by all major governments and corporations. Without political interest the private sector will simply not be able to get their feet off the ground with these exciting opportunities to make fossil fuel internal combustion obsolete. The initial investment price for the transition will be too much and lack of governmental regulations on nontraditional nitrogen based greenhouse gases will offset the environmental justice that it is supposed to spark.