Generalities -- pt. 1. Heat engines. A minimum of thermodynamics and of the kinetic theory of gases -- Mechanical heat engines -- Ocean thermal energy converters -- Thermoelectricity -- Thermionics -- AMTEC -- Radio-noise generators -- pt. 2. The world of hydrogen. Fuel cells -- Hydrogen production -- Hydrogen storage -- pt. 3. Energy from the sun. Solar radiation -- Biomass -- Photovoltaic converters -- pt. 4. Wind and water. Wind energy -- Ocean engines