Municipal solid waste disposed in landfill sites decomposes under anaerobic conditions and produces so-called landfill-gas, which contains 30%–40% of carbon dioxide (CO₂) and 50%–60% of methane (CH₄). Methane has the potential of causing global warming 25 times more than CO₂. Therefore, migration of landfill-gas from landfills to the surrounding environment can potentially affect human life and environment. Thus, this research aims to determine municipal solid waste generation in Oman over the years 1971–2030, to quantify annual CH₄ emissions inventory that resulted from this waste over the same period of time, and to determine the economic and environmental benefits of capturing the CH₄ gas for energy production. It is found that cumulative municipal solid waste landfilled in Oman reaches 3089 Giga gram (Gg) in the year 2030, of which approximately 85 Gg of CH₄ emissions are produced in the year 2030. The study also found that capturing CH₄ emissions between the years 2016 and 2030 could attract revenues of up to US$333 million and US$291 million from the carbon reduction and electricity generation, simultaneously. It is concluded that CH₄ emissions from solid waste in Oman increases enormously with time, and capture of this gas for energy production could provide a sustainable waste management solution in Oman.