Apart form Geothermal energy (heat from the core of the Earth) and Tidal energy (from the Earth's spin) all energy comes from the Sun which grew the organisms that form fossil fuels, drives the wind and rain and feeds plants. Sunlight is free!
Energy is not renewable. The sources to make that energy may be. After the initial cost of plant and equipment some sources are practically free so the only costs are maintenance costs..
There are some energy sources, such as wind energy, solar energy, and geothermal energy, that are available in abundance - basically for free. But please note that there is always a cost to convert such energy types into something useful. The energy is free; converting it into useful energy to run machinery is not free.
If you mean "free of cost", you simply need some investment to use any energy source.If you mean free energy in the sense of perpetual motion machine, this simply isn't how our Universe seems to work. There is no known method to get energy where there was none before. Strange as it may seem, this "conservation of energy" is related (by Noether's Theorem) with the fact that physical laws don't change over time - in other words, if it were possible to get "free energy", then physical laws would change over time!
Sorry, I don't have any answers for What are some energy sources of extinction?
Nuclear Energy
Explain why energy is necessary to chemical reactions, and describe some common sources of energy.
Coal and all types of fossil fuels.conventional sources mean that was traditionally known to people.
some energy sources are non renewable but some are renewable
Some source of energy are solar panels.
God created energy.
Governments encourage the development of new energy sources by some money and by some other thing.
wind, solar, tidal