This chapter concludes the book and points to some key ideas going forward. Rather than a future premised on the notion of colours of hydrogen the future of hydrogen is likely to be shaped by the need to manage two supply chains dedicated to separate products. One will be pipeline purity hydrogen and the other will be high purity hydrogen for mobile fuel cell applications. Ammonia is likely to be an important commodity, as may also be the case for other hydrogen carrier molecules. The world faces a pressing challenge to decarbonize and this book, and this chapter point to the fact that molecular energy carriers will have a major role to play. Electricity will grow greatly in importance in the low carbon future, but it is most unlikely to be the entire solution to the challenges that we face.