Renewable energy sources
Energy is the ability to perform work and appears in various forms. All natural forms of energy can be divided into two fundamental groups:
- non-renewable or exhaustible
- renewable or inexhaustible
Both of these forms represent energy sources that can be used for producing electricity and heat.
The actual name renewable is derived from the fact that energy is spent in the amount that does not exceed the pace at which it is naturally formed. At times, the group of renewable energy sources include sources with reserves so plentiful in nature that they can be used for millions of years. On the other hand, non-renewable energy sources are considered to be those sources with reserves estimated to last for tens or hundreds of years, whereas the process of their creation occurs over millions of years.