Human energy consumption has developed steadily, throughout human history. Early humans had modest energy needs, mostly food and fuel for fires to cook and keep warm.
In the present society, humans consume around 110 times as much energy per individual as early humans. The majority of the energy we use nowadays come from fossil fuels (stored solar energy). However fossils fuels possess a disadvantage in that they are non-renewable on a human time scale and cause other potentially dangerous effects on the environment.
In any case, the exploitation of most energy sources (with the possible exception of direct solar energy employed for heating), ultimately depend on materials on planet Earth.
Renewable energy resources is usually defined as energy that originates from resources which are naturally replenished on a human timescale including wind, sunlight, tides, rain, geothermal heat and waves. Renewable energy replaces conventional fuels in 4 distinct areas: hot water/space heating, electricity generation, rural (off-grid) energy services and motor fuels.
About sixteen% of global final energy consumption presently originates from renewable resources, with ten% of all energy through traditional biomass, mainly employed for heating and 3.4% from hydroelectricity. New renewables (modern biomass, small hydro, solar, wind, biofuels and geothermal) account for another three% and are developing rapidly. At the national level, a minimum of 30 nations around the planet already have renewable energy contributing greater than 20% of energy supply.
Energy sources are utilized as fuels. Fuel is burned in machinery to produce heat (such as in a home heating system) or motion (such as in a car). When fuels are employed for producing electrical energy, heat or motion leads to a generator to rotate, creating electrical power for everyday use in businesses and homes.
Energy sources can be classified into 2 types: nonrenewable and renewable. Nonrenewable resources, including nuclear material and fossil fuels, are eliminated from the earth and can be depleted. These resources have been one of the most used type of energy in the contemporary era.
Renewable resources, including water, wind, geothermal and solar, originate from sources that regenerate as quickly as they are consumed and are continually available. Some, for example biofuel produced from food crops and other plants, are replenished every expanding season. During the early part of the twenty first century, renewable sources have become very popular as nonrenewable sources have started to be depleted.