Energy and environment, wood and PELLET

Humans use a large range of energy resources (coat, petroleum, natural gas, biomass, wind, solar light, geothermic heating, radioactive isotopes) to have different forms of energy (mechanic, thermic, electric, chemical) used for their activities. Wood, with the animal strength, was the first energy resource that humans known to use , and today it's still one of the most important energy resources for domestic heating and for food cooking.
Living in computers and electronic devices age, we normally think electric energy is the "highest tone" form that humans use. At the contrary, modern societies use electric energy for not over 35-40% of their total requirements; the "poor" thermic energy gives human all the remaining!
 
Which is energy-environment relationship?: Mass media bring us information about energy production and use that made us aware of their high impact on the environment.