This research presents decision-support tools for the assessment of energy systems development at national and regional scales. For this purpose, mathematical frameworks for the design and optimisation of energy systems are developed. A methodology is proposed as a preliminary assessment of shale gas development. For this purpose, economic and environmental metrics are proposed to address different aspects of well-pad designs such as productivity and water intensity. The outcome of this methodology is included in a comprehensive optimisation-based decision-support tool developed to address the design of shale gas supply chains along with water management strategies. In this framework, the optimisation of well-pad designs is regarded as a critical decision variable. Next, implications of water scarcity, the role of economy of scales, and the impact of wastewater quality are addressed through a case study focusing on the development of shale gas supply chains in Colombia. The production of synthetic natural gas is studied as a possible substitute of natural gas. In this case, an optimisation approach is proposed to address decisions such as feedstock procurement, transportation and optimal production schemes of BioSNG and power. The mathematical framework can be implemented to investigate policies that encourage the development of renewable energy sources. The impact of uncertainty in input data is addressed through a global sensitivity analysis (GSA). The implementation of GSA assists not only in the identification of key parameters in the design of BioSNG supply chains, but also in revealing recurring trends in light of uncertainty. Finally, the development of BioSNG supply chains in the UK is investigated through the implementation of the proposed mathematical framework
