Mechanisms of change toward renewable energy, in production and consumption, are discussed in this book; meaning, the socio-economic processes that generate innovations in energy resources and services. Such mechanisms of change enable policies in line with societal interests. This discussion refers to assessments of changes in the past, mainly based on the interpretations of statistical data starting from the early 1800s and ending in the late 2010s. Several mechanisms of change are pinpointed without prioritising preferences or hierarchies for actions, as they collectively represent various situations across countries, interests, and social groups. The main message is optimistic. The continuation of past trends, driven by those mechanisms, would enable the generation of renewable energy that is hundred times larger, earning an income per person of nearly fourfold and doubling energy consumption per person in half the CO2. This perspective is attainable if people uphold preferences for value-added energy services rather than costs, and authorities resist protectionism in energy production.