Hydrogen and ammonia, touted as alternatives to fossil fuels, are not as innocent as thought

As the world counts down to the launch of the first cargo ship to run solely on ammonia, an academic paper published in the journal Proceedings of the National Academy of Sciences has sparked a new debate. According to an analysis by Amilcare Porporato and his colleagues at Princeton University, in the worst-case scenario, the use of ammonia as a fuel could result in a greenhouse footprint as heavy as burning an equivalent amount of coal.

This is because when ammonia leaks or does not burn completely, the nitrogen it contains turns into reactive species. Nitrous oxide (N2O), one of these compounds, is a pollutant 273 times more potent than carbon dioxide. It is a key component of acid rain and also plays a role in the formation of particles that cause asthma. Another dangerous waste product from ammonia is nitrogen oxides.

According to the study, "green hydrogen," described as the world's cleanest fuel, is also not as innocent as thought. Leaks from pipelines and other infrastructure cause an increase in the levels of methane, another potent greenhouse gas. This is explained by the fact that chemicals that play a key role in the process of methane breaking down in the atmosphere react with hydrogen and disappear. In other words, as the amount of hydrogen in the atmosphere increases, the chemicals that eliminate methane decrease. An analysis conducted on green hydrogen last year warned that if leakage rates reach 10 percent, the negative effects on the climate would be half that of using an equivalent amount of fossil fuels.

COULD NEGATE THE BENEFITS

A study conducted at the Joint Global Change Research Institute in 2022 also warned about the risks that the use of ammonia in maritime transport would create. The report stated that if the entire sector were to switch to ammonia, the market would need four times the amount of chemicals it currently produces, and if only 4 per thousand of this were to turn into nitrous oxide, the benefits of abandoning fossil fuel use would be negated.

Currently, 180 million tons of ammonia are produced annually in the world, and most of this is used for fertilizer purposes. The research by Porporato and his colleagues is based on the assumption that ammonia production will rise to the level of 1600 million tons between 2060 and 2070.

Hideaki Kobayashi, an engineer at Tohoku University in Japan who develops ammonia turbines, suggested in a statement to Science Magazine that the research was "too pessimistic," saying, "The turbines we develop burn ammonia efficiently. They produce very little or no nitrogen. This is then filtered in the catalytic converters in the exhaust systems."

One of the main reasons why ammonia has recently come to the fore as an alternative fuel is the ease of storage. To convert hydrogen into an energy source, it is necessary to lower its temperature to -253 degrees or increase the atmospheric pressure on it 700 times to liquefy it. Ammonia, on the other hand, can be stored by cooling it to -33 degrees or by increasing the atmospheric pressure 9 times. Ammonia, which can even be stored in liquid form at 20 degrees, becomes much easier to transport and store compared to hydrogen.

News Source: 12punto