The various forms of energy are the primary materials from which power is generated. They are later converted into secondary forms like fuels and electricity. They are then transferred through different channels to provide energy for our homes, automobiles, industries and even our lives. Energy sources can be classified as renewable or not.

Renewable (or clean) energy is produced from natural resources that are constantly replenished. Examples include wind power, solar power, water power and geothermal energy. Fossil fuels (coal oil, natural gas) are considered non-renewable as they form at a much lower rate than what we consume from their resources, which means that they will eventually be exhausted.

Solar energy can be harnessed by a single rooftop or in large solar power plants. Solar energy can be converted into photovoltaic energy, which generates electricity directly. Water can be used for the production of hydropower as well as for energy from tides and waves. Geothermal energy is derived from hot water reservoirs underground. Bioenergy can be derived from organic sources like woody plants, animal dung and human waste.

Renewable energy is not only green but also more affordable than fossil fuels. Renewable energy is costly and requires a large infrastructure to harvest and distribute the energy. This can lead to complicated trade-offs in environmental as well as economic aspects. The development of these technologies is continuing to expand, and they are making strides over the more traditional fuels. In the future renewable energy may be more cost-effective than oil and coal.