The two primary critical challenges facing our society nowadays, the depletion of petroleum reserves and the global warming, necessitate the substitution of transport fossil fuels with sustainable, recyclable, and cleaner fuels. The direct combustion of metal fuels is attractive due to their high-energy density and the ability to regenerate them through the reduction of their oxide products. Their regeneration is economically beneficial and environmental-friendly when performed using renewable energy sources, providing sustainability for the combustion/reduction cycles. Thus, the following chapter highlights the research advancement employed for the development of a metal-fueled combustion engine and a solar recycling reduction process for the regeneration of metal fuels. To this day, an 80% heat-to-mechanical conversion efficiency is attained when burning Mg particles in a swirled-stabilized metal-air combustor, with the ability to collect 98% of the produced submicron magnesia products. Using concentrated solar energy, a recycling yield of 68% and 96% is achieved for Al and Mg, respectively, by optimizing the operating parameters allowing to produce pure stable microsized metal powders. Further investigation is required to improve the combustion engineering of Al particles and to reduce the formation of unwanted Al-oxycarbides by-products during the carbothermal reduction of alumina.