Ammonia as an alternative fuel for vehicular applications: Paving the way for adsorbed ammonia and direct ammonia fuel cells

This article is a roadmap for researchers in this field to look for an efficient and reliable alternative for fossil fuels in the form of ammonia. We have discussed different storage techniques, with one of them being ‘solid ammonia storage method’ using MOFs and metal ammine complexes as a better option to deal with ammonia toxicity. Besides, we have discussed various approaches of direct and indirect ammonia being used in internal combustion engines as fuel or within fuel cells for creating a sustainable energy source for the onboard vehicular application. To discuss ammonia's feasibility as a commercial fuel, a detailed discussion on ammonia economy is important. So, in the later sections of the article, we have discussed ammonia economy, emerging technologies for ammonia production, cost analysis, investment, the economics of vehicle engines and fuel cells, and opportunities ahead. In the article, apart from just advocating the feasibility of using ammonia as a future fuel, the authors have also talked about its downsides, associated challenges, and how there are alternative pathways to use ammonia indirectly as well. The authors believe that in the literature, very few articles present such a broad discussion on ammonia's feasibility as a future fuel. Thus, we believe this article will help the readers in formulating their own opinion regarding ammonia and work on finding the right fuel for a sustainable future.