The original energy source for all human activity was the sun via growing plants. Solar energy’s main human application throughout most of history has thus been in agriculture and forestry, via photosynthesis.
Wood was the earliest manipulated energy source in human history, being used as a thermal energy source through burning, and it is still important in this context today. Burning wood was important for both cooking and providing heat, enabling human presence in cold climates. Special types of wood cooking, food dehydration and smoke curing, also enabled human societies to safely store perishable foodstuffs through the year. Eventually, it was discovered that partial combustion in the relative absence of oxygen could produce charcoal, which provided a hotter and more compact and portable energy source. However, this was not a more efficient energy source, because it required a large input in wood to create the charcoal.
Motive power for vehicles and mechanical devices was originally produced through animal traction. Animals such as horses and oxen not only provided transportation but also powered mills. Animals are still extensively in use in many parts of the world for these purposes.
Animal power for mills was eventually supplanted by water power, the power of falling water in rivers, wherever it was exploitable. Direct use of water power for mechanical purposes is today fairly uncommon, but still in use.
Originally, water power through hydroelectricity was the most important source of electrical generation throughout society, and is still an important source today. Throughout most of the history of human technology, hydroelectricity has been the only renewable source of electricity generation significantly tapped for the generation of electricity.
Wind power has been used for several hundred years. It was originally used via large sail-blade windmills with slow-moving blades, such as those seen in the Netherlands and mentioned inDon Quixote. These large mills usually either pumped water or powered small mills. Newer windmills featured smaller, faster-turning, more compact units with more blades, such as those seen throughout the Great Plains. These were mostly used for pumping water from wells. Recent years have seen the rapid development of wind generation farms by mainstream power companies, using a new generation of large, high wind turbines with two or three immense and relatively slow-moving blades.