Ammonia Is A Great Fertilizer But Would Be A Terrible Shipping Fuel

In a petrochemical chemical refinery industrial refinery, a large, round, metallic storage tank, designed for high pressure and built strong with pipes and equipment to store ammonia, stands firm. As discussed in this series that centers around the electrification of everything, bulk shipping will see a sharp decline with the peak in fossil fuel demand, and batteries will fuel all inland and most short journey sea transportation. In the prior article, we examined hydrogen as a marine fuel. Now, we turn our focus to ammonia.

Ammonia is an incredible substance, an essential modern fertilizer without which only a few billion people would survive. It needs to be stated that the purpose of this analysis is not to discount the value of ammonia but to debunk the myth of it being a suitable marine fuel replacement, an idea deserving of being buried at the bottom of the Mariana Trench.

Projecting to 2100, only 70 million tons of diesel energy equivalent shipping fuels will be needed. Several alternatives have been explored with some gaining considerable traction. The ammonia industry, in its attempts to push its product, makes certain claims that do hold up. Firstly, we currently produce a hefty 150 million tons a year. Secondly, we already ship large quantities of it across oceans and routinely transfer it between ship and shore. Lastly, it burns cleaner than diesel, a mostly true statement that deserves further scrutiny.

So what is ammonia? It comprises one nitrogen atom and three hydrogen atoms. The hydrogen burns and provides energy, the nitrogen doesn't. However, when high energy and oxygen are present, as when hydrogen is burning, nitrogen tends to form nitrous oxides, great a concern as they are harmful. Nitrogen can combine with oxygen to form what we commonly refer to as laughing gas which is 273 times more potent than carbon dioxide as a greenhouse gas with a long atmospheric lifespan. Nitrous oxide, resulting from nitrogen binding with two oxygen atoms, leads to smog formation which impacts lung health. The nitrogen in the combustion of ammonia exacerbates this issue.

Current modes of ammonia production rely on fossil fuels. Hydrogen is removed from coal, oil, or gas through the steam reformation process creating large CO2 emissions. The Haber Bosch process, which uses this hydrogen with the nitrogen-rich air in pressure vessels, has enabled us to feed eight billion people. But every ton of ammonia contains about 0.18 tons of hydrogen leading to a carbon debt of two to six tons of CO2. Plus, ammonia only has 42% of the energy as marine diesel due to non-burning nitrogen. A significant increase in ammonia use would multiply the carbon debt.

While ammonia may be cheaper than diesel, it requires two and half times the quantity for the same propulsion, making it doubly expensive. During the European energy crisis, ammonia prices soared to $1,300 per ton, proving that it is neither cheap nor green currently.

Producing green ammonia is high energy intensive most of which goes into extracting hydrogen from water using electricity. Assumptions of significantly reduced costs for ammonia do not have a solid foundation. Safety is also a concern as even low concentration of ammonia can cause serious damage to human health. The feasibility of treating shipping fuels in the same strict manner as hazardous chemicals is debatable. Not forgetting that at four times the cost, with high nitrous oxide emissions and stringent safety considerations, the chances of the ammonia industry realizing its dreams of market expansion are low, and this could spell disaster for the rest.