Sustainable energy management involves the provision of energy supply that meets the needs of the present without compromising the ability of future generation to meet their needs. Sustainable energy strategies must involve energy savings on the demand side, plus on the supply side, efficiency improvements in energy production and the replacement of fossil fuels by various forms of renewable energy. This paper analyzes the issues involving utilization of different energy sources. Formulating a dynamic optimization problem, expressions are derived for optimal energy supply prices from each of three energy sources, wind energy, hydroelectric power, and fossil fuels. Based on the economic characteristics of the energy sources, an optimal solution is derived that involves both periods of specialization in a single energy source as well as the simultaneous utilization of three available sources.