Wind power is the fastest growing energy source in the world. A wind turbine works the opposite of a fan. Instead of using electricity to make wind, a turbine uses wind to produce electricity.
The wind turns the blades, which spin a shaft, which connects to a generator and produces electricity. The electricity is sent through transmission and distribution lines to a substation, then on to homes, business houses and schools. Wind turbines do not have any adverse effect on the environment. That's why wind power is gaining popularity. It is also becoming economically competitive with more conventional power sources-a fact that's greatly improving its prospects as a viable energy source.

The six basic principles of sustainable development are:
(i) To respect and care all forms of life.
(ii) To improve the quality of human life.
(iii) To conserve the earth's vitality and diversity. 
(iv) To minimise the depletion of natural resources.
(v) To change the personal attitude and malpractices towards the environment.
(vi) To encourage communities to care for their own environment.

Natural resources are classified into different groups on different basis.
These are:
(i) On the basis of their level of development and use:
(a) Actual Resources and
(b) Potential Resources.
(ii) On the basis of their origin :
(a) Abiotic and
(b) Biotic Resources.
(iii) On the basis of their distribution:
(a) Ubiquitous Resources and
(b) Localised Resources.
(iv) On the basis of stock:
(a) Renewable resources and
(b) Non-renewable resources.

There are many reasons for treating humans as a resource.
Some of the important reasons are :
(i) Human resource refers to the number (quantity) and abilities (mental and physical) of the people.
(ii) It is the human ability which transfers physical materials into valuable resources.
(iii) People can make full use of nature if they have skills and knowledge.
(iv) Education and health are two important factors that make man a precious resource.