When man first appeared on Earth he had no implements, no clothes, no farms and no mineral fuels – his only tools were his brains, hands and muscles.
Everything that enables mankind to live comfortably in a world where nature is indifferent to our survival has been discovered, invented, mined or created by our inventive ancestors over thousands of years.
The history of civilisation is essentially the story of man's progressive access to more efficient, more abundant and more reliable energy sources - from ancestral human muscles to modern nuclear power.
There are seven big steps on the human energy ladder – fire, farming, solar power, gunpowder, coal, the steam engine and nuclear power.
Man's first and greatest energy step was discovering how to harness fire for warmth, cooking, hunting, metal working and warfare.
For centuries the main fire-energy fuels were organic natural resources such as wood, charcoal, peat, grass, animal dung and fats/oils extracted from animals and plants. As human population increased, these energy sources became scarce as the land and seas around towns and villages were stripped of their natural carbon fuels.
The second step on the energy ladder was built when some smart hunter/gatherers discovered how to access more reliable energy from domesticated animals and plants. Sheep, cattle, goats and pigs provided a steady supply of carbon-based food energy, and dogs, horses, donkeys and camels multiplied human energy for transport, hunting and warfare. Farmers also nurtured fruiting trees and grasses such as einkorn, wheat, rice, barley, oats, corn and sugar cane. These provided more dependable and abundant food energy for humans and their animals.
About this time humans ascended the third step on their energy ladder – the ability to harness wind/hydro/solar power for sailing ships, windmills, water-wheels, grain mills and drying food. The low energy density and unpredictability of these weather-dependent energy sources was obvious, even to our ancestors.
The fourth big step was the invention of gunpowder by the Chinese, which gave humans the first glimpse of the enormous power of concentrated chemical energy. This led to the widespread use of explosives for hunting, armaments, mining, civil engineering and entertainment.
The fifth energy step was a bigger one - the discovery of how to obtain and use coal, and centuries later, oil and gas. The energy density and abundance of these hydro-carbon fuels gave an enormous boost to human access to energy, and massively relieved the pressure on forest fuels and animal fats.
The sixth step on the energy ladder was truly gigantic - British inventors and engineers built the first practical steam engine. That invention transformed the world. Suddenly steam engines were moving trains and ships, pumping water, generating electricity and powering factories, traction engines and road vehicles. Most steam engines were driven by coal, but wood, other hydro-carbons, concentrated solar energy or nuclear power could be used.
Steam cars and electric cars got a good work-out over 100 years ago, but neither could compete with a new invention - the oil-powered internal combustion engine. This small but powerful engine resulted in the replacement of steam and electric motors for mobile engines but the mighty steam engine still dominates electricity generation.