This book publishes some papers presented at the 4th International Conference on Water Energy Food and Sustainability (ICoWEFS 2024), a major forum to foster innovation and exchange knowledge in the water-energy-food nexus. The world is facing unprecedented challenges to mitigate climate change and adapt to its negative impacts, affecting global economy and society. Europe intends to take the lead on the transition to sustainability, as a chief priority of Horizon Europe is a European Green Deal to transform Europe in a climate-neutral continent, fostering disruptive innovation and the deployment of new technologies and innovative solutions, helping creating a sustainable future. Innovation regarding water, energy, agri-food, bio-economy, natural resources and environment will speed up the transition towards sustainability, promoting water and food security in the world. A climate-neutral continent by 2050 will drive technological, economic and societal transformations towards circular economies and green and clean technologies, and the decarbonisation of energy-intensive industries.