This Chapter ranges through a wide variety of production and demand management problems related to energy commodities systems. The Oil and Gas production enhancement is discussed via oil wells optimal placement as well as water and gas optimal injection, namely waterflooding and gas lift. Further is analyzed the optimal schedule and design of commodities generation in energy hubs and combined cooling, heat and power systems, reaching finally the chemical processes where the specification of the products is taken into account, with mixing tanks, pools, and blending points. Overall, each of these problems is qualitatively discussed identifying the typical objective functions, variables and constraints generalizing its structure, the problem typology is identified as well as the most common methods to solve it.@en