The document discusses various types of energy sources including conventional/non-renewable sources like coal and oil as well as non-conventional/renewable sources like solar, wind, tidal, hydro, biomass and geothermal energy. It explains how each type of renewable energy is produced, for example, how solar cells convert sunlight to electrical energy, wind turbines convert kinetic wind energy to electricity, and tidal power uses ocean wave movement to rotate turbines. The document also discusses advantages of renewable energy sources like being continually replenished and having fewer emissions than fossil fuels, as well as challenges like technical and economic uncertainties.