Energy is lifeblood of our modern societies. However, traditional energy systems use centralized facilities to generate electricity (e.g. use fossil fuels or nuclear units), and to process the natural gas (e.g. Wintershall Dea AG), and then transfer them to consumers through power transmission lines and gas pipes. As such, (1) large energy transmission facilities may be needed even for small and remote communities; (2) such energy systems are not sustainable, can produce Green House Gas (GHG) emissions; (3) it is more difficult to incorporate locally available energy resources; and (4) as energy delivery systems span wide geographical regions, they are more susceptible to extreme weathers, earthquakes, or even sabotages.\r\nTo improve the overall reliability and efficiency and to reduce GHG emissions, locally available renewable energy resources should be utilized whenever possible. As a result, a new type of energy systems, known as “Integrated Energy Systems” has emerged. By combining electrical, thermal energy with variety of energy storage devices, one can provide a reliable energy supply to local customers. However, there are still many unanswered questions and technologies to be developed for such systems. This project investigates lifecycle carbon footprints of several energy resources commonly adopted by “Integrated Energy Systems”, and to develop methodologies to rank them, finally determine the optimal strategies to ensure the entire system work in harmony.