The complex issue of energy is not an easy puzzle to solve. Russia's invasion of Ukraine at the beginning of 2022 made that painfully clear once more. The resulting energy crisis has exposed our vulnerability and dependence yet again. It should not be surprising then that the vast cleantech 'energy' sector is receiving a great deal of attention. Innovative solutions offer many technical, political and societal options in terms of cost, reliability and sustainability. In this next chapter, we bring together a selection of energy-related topics from expert perspectives.