Energy is a vital resource in modern life. With increasingly limited availability of traditional energy resources, e.g., oil, coal and nuclear, together with environmental concerns, there is raised awareness that energy needs to be both used more efficiently and generated in line with thinking on sustainability. Ready access to ‘clean’ energy is essential if we wish to maintain our current way of life without compromising our wellbeing or the carrying capacity of the planet. This paper aims to analyse the differences and similarities in energy supply and demand between two very different cities. Masdar City, founded in 2008, is a dynamic new Middle-Eastern city being built in a desert environment. Its aim is to be the most sustainable city in the world and offers an exciting opportunity to provide unique insights into the application of different innovative technologies as ‘new-build’ within an urban environment. Birmingham is a well-established post-industrial city that has evolved over fourteen hundred years. It was one of the fastest growing cities in 19th century England (Popp and Wilson, 2009) [1]. To do this a material flow analysis approach has been adopted to provide a framework for the study. The energy-related opportunities and mutual benefits that each city can gain from the experiences of the other are explored and five emergent issues are identified: innovation and experimentation, lock-in, balance, resilience and governance. This work shows how a greater understanding of common issues can lead to more sustainable, resilient and robust cities, able to face the challenges of the next 50 years.