Energy, environment, health, food and water are the sectors of critical significance and concern to the world, especially to the rapidly developing countries. These fields are intertwined in many complex ways and our excessive dependence on polluting fuels has had extremely serious and progressively deleterious influence on the quality of our lives. Since energy drives the engines of growth, our increasing demand for energy is unavoidable in the face of development, but in the light of the issues mentioned above we must necessarily seek clean forms of energy. Amongst the various forms of renewable energy, solar energy is the most abundant and clean source, and it can be harnessed in various interesting and effective ways. For a long time it was considered to be uneconomic, but with improvements in technologies, new inventions during the past decades, and novel possibilities generated by the emergence of nanoscience and nanotechnology, the solar economics are gyrating towards favourable domains of utilization. In this talk I will discuss this scenario taking some examples from our own research on Dye and Quantum Dot Sensitized Solar Cells, photo-electrochemical (PEC) water splitting and visible light photocatalysis. The materials, electrodes, and systems required to be developed in this effort are synergistically similar to the requirements of other related fields such as energy storage (batteries and supercapacitors), and fuel cells, if functional carbon is included innovatively. We have thus ventured into the domain of synthesis and science of novel forms of carbon for such energy applications. I will discuss a few examples of this research as well. Interestingly, such suitably engineered high surface area carbon based systems are also useful for pollution control.