Energy is everywhere . Examples are solar, wind, water, plants and animals.
Energy from the Sun can be converted directly or indirectly into other forms of energy, such as heat and electricity. Calculators, space vehicles and satellites use solar cells, which convert sunlight into electricity.
Why is food a source of energy? By eating plants, humans and animals take these energy storing molecules to keep up their life processes. By eating animals, the energy captured by plants is obtained. Thus, the food we eat has energy. We use that energy to work and play.
The differences in temperature and atmospheric pressure produce wind. Humans have been using wind energy for over 2000 years. The energy is used to sail ships, grind corns or pump water. Wind turbines are used to harness the movement of air to produce electricity. The wind turns the blades, which turn a rotor shaft. This produces mechanical power used to drive an electric generator. To produce large amounts of electricity, many machines are installed together to form a wind farm.
The use of energy in the form of fuels began from the exploitation of coal deposits to the exploitation of petroleum and natural gas fields. Petroleum goes through a refinery where it is made into many products such as gasoline and diesel to be used as fuels in transportation. It has been only half a century since nuclear power began being used as an energy source.
Dry cell, acid accumulator, nickel cadmium and lithium are examples of batteries which store energy. Energy stored in the chemicals present in these batteries is transformed to electrical energy which are then changed in the form of sound, light or kinetic energy in our electrical appliances.
From all the different sources of energy, the Sun is the main source and as such is the ultimate source of energy.