“Sustainability” is maintaining or improving the material and social conditions for human health and the environment over time without exceeding the ecological capabilities that support them. The dimensions of sustainability are economic, environmental, and societal. Energy demand continues to grow worldwide while extraction of fossil fuels becomes more difficult and expensive. The ways we produce, convert, store, and use energy are changing earth’s climate. Nearly two-thirds of global GHG emissions are related to production and consumption of energy. This makes the sustainability in energy sector critical to mitigating global warming and climate change. Increasingly resource-intensive consumption across the world requires novel and sustainable energy technologies and management. Therefore, this chapter focuses on the measurable sustainability and life cycle analysis in energy sector and addresses the implications of depletion of natural energy and material sources.