Introduction

Globe fossil fuels consumption

At present, the primary energy (mainly the fossil fuels) shortage becomes a globe issue when it is the blood of development and civilization. In fact fossil fuels includes three parts: Coal, Petroleum and Natural gas that formed natural process such as anaerobic decomposition which would take millions of years. According to Energy Information Administration in 2007, fossil fuels account for 86.4% of the total primary energy consumption. And the world energy consumption would grow about 2.3% per year. It indicates that the reserves of fossil fuels are being depleted much faster than new one are being made. Some researches have proven that if the consumption rate of fossil fuels remains same until they are used up, there is enough oil to last 42 years, when there is enough natural gas to last 61 years and there is enough coal to last 133 years. Furthermore, the combustion of fossil fuels would emit huge amount of carbon dioxide which becomes one of the main causes of globe warming. So renewable energy which could be naturally replenished at a constant rate comes along to meet the abundant energy consumption in the future. And it is assumed to have less impact to the environment.
The blog would be divided into 5 parts that represents the 5 main types of renewable energy: Solar, Wind, Geothermal, Tidal and Biomass.
There is only one thing that should be considered is that, according to energy conservation, the energy would not disappear or exhausted. It could only be transmitted from one type of energy to another type. All of energy that used by human beings are end up with heat which could not be used. So in theory, the energy is infinite. However, we just have not found the best way to use it. 

Reference
^ "U.S. EIA International Energy Statistics Retrieved 2010-01-12.