Simply, energy is the amount of force or power that can be used to perform work. There are various forms of energy - including potential energy, kinetic energy, and nuclear energy. Common examples of these in play are:
- potential energy is stored energy. For instance, if you lift a book, it will gain potential energy - due to gravity - and the book falling will be the work. A compressed spring also has potential energy - and work can be done by harnessing the force exerted when it starts to stretch.
- kinetic energy is energy in motion - anything that is moving has this energy. A collision between cars has damage partly because of the kinetic energy from the two moving vehicles.
- Nuclear energy is energy derived from nuclear reactions. These reactions release energy which can be captured and transformed to other forms of energy - such as in nuclear power plants.
Energy that we use in everyday life can either be renewable or non-renewable. Just as their names imply, renewable energy is something that can be renewed - i.e. there can be a constant source of it; while non-renewable energy, once consumed is not available anymore.
Renewable energy is energy derived from natural resources that replenish themselves in a timely manner. For instance, wind turbines that harness the wind, solar panels that get energy from the sun, or turbines that harness kinetic energy from waterfalls. Non-renewable energy is energy that is obtained from the earth's limited resources like fossil fuel, which can be depleted and in time consumed entirely.
There are advantages and disadvantages to both types of energy. Renewable energy, for instance, is not depleted, and is theoretically limitless. It also has a significantly smaller carbon footprint. Meanwhile, harnessing these sources is not easy to accomplish at first - due to cost and complexity of materials and facilities needed. They are also limited by forces outside human control - wind strength, exposure to sun. However, there are always solutions to these, and they remain a significant alternative to the ever-depleting non-renewable fossil fuels. Meanwhile, non-renewable sources are cheaper and easier to use, and produce more power in smaller amounts; however, they won't last forever. They also have larger carbon footprints and other associated toxic chemicals, either as by-products of their use, or in harvesting them.