Life cycle and socio-economic assessments of the current natural gas and related energy systems are being undertaken within the NATURALHY Project. This work forms the basis for comparison of the relative benefits of the transition towards a mixed natural gas/hydrogen system, and the eventual development of complete hydrogen-based energy supply systems. Relevant primary energy inputs, major resource depletion, and greenhouse gas emissions associated with global climate change are analysed. The socio-economic assessments generate inventories of direct and indirect job creation and of internal economic costs. A modular approach has been adopted to ensure that all components of the systems under investigation can be evaluated in a coherent and effective manner. These studies are being performed as part of the NATURALHY Project which is being co-financed by the European Commission under its Sixth Framework Programme for Research and Technological Development.