Approaches towards substituting fossil fuel sources of their products, energy and petrochemicals are elaborated. Synthesis gas (CO/H2) provides an intermediate for reconverting waste (from plastics and biomass) as well as carbon fuels into petrochemicals from methanol to petrol to waxes. Energy sources such as nuclear power and photovoltaic cells are explained. Modes of forming hydrogen and avoiding the release of greenhouse gases to afford a green fuel are explained. Electrochemical methods provide secondary energy sources are alternatives are compared: e.g. by powering transport using fuel cells or batteries. The demands of these technologies on the supplies of key elements like lithium and cobalt are discussed to understand whether developments may or may not be sustainable.
