Sierra Leone is one of the least developed countries in the world, with an economy strangled by the necessity of importing rice to feed the population. In part, this deficit results from domestic farmers rarely using inorganic fertilizer, which is synthesized from fossil fuels internationally. Here, we evaluate the economic benefits of producing green ammonia from renewable local hydropower for low-carbon cost-effective fertilizer production. Its use as fertilizer estimates a 30-year net present value (NPV) of ∼$230M (∼165% return of investment) compared with simply importing fertilizers, which would already save at least $50M a year compared with the current situation of importing rice, but hinges on additional external factors related to implementing modern agriculture. In addition, green ammonia can buffer seasonal fluctuations of hydroelectricity from 900 MW to 50 MW and produce a consistently available 370 MW of power. Although this study presents an initial analysis of Sierra Leone as a case study, it exemplifies the possible economic and social benefits of green ammonia in developing countries. The use of ammonia-based fertilizers is estimated to feed ∼80% of the current world's population through the high-energy and capital-intensive Haber-Bosch process, using methane or coal as feedstock. Current research is developing technologies for the distributed production of green ammonia using solely renewable energy, opening new opportunities to those countries with access to solar, wind, and hydro power. This paper explores the implications of such green ammonia in sub-Saharan Africa, taking Sierra Leone as an example because of its high hydropower capability. It illustrates the economic and social benefits of locally produced fertilizers using their own renewable energy resources versus importing fertilizers or other agricultural products. In addition, green ammonia can also be used to buffer the seasonal variations of renewable energy, leading to a consistently available power to serve as the foundation for development. Green ammonia from renewable resources has the potential to transform the economies of sub-Saharan African countries such as Sierra Leone with high hydropower potential. Here, we show that the use of green ammonia is economically viable and will not only provide fertilizers to feed the population and modernize agriculture but also produce a consistently available power, buffering the seasonal fluctuations of renewable energy.