Since the Scientific and Industrial Revolution in the 17th and 18th Century, we have been trying to enhance every human activity with the aid of a machine or chemicals, least realizing that this will ever cost damage to our environment and to man himself.

We have cars, Aero planes, railways, air-conditioners, refrigerators and kitchen appliances etc to help man improve his quality of life. All these devices have to work on energy and the commonly used sources of energy today to generate electricity are coal and gas. These are conventional sources of energy popularly known as fossil fuels. The availability of these machines radically changed our lifestyles.

In the middle of the last century, amidst the glamour of modernity and progress, some scientists started warning of the damage caused by this so-called modern lifestyle to our own environment. The change in Polar Regions was enough proof that we have already caused significant damage to our ozone layer. The root cause of this damage was the source of energy that we used for our modern gadgets. So energy issue and environmental issue are closely linked and needs to be discussed together rather than in isolation. The whole issue of alternative energy sources took momentum from these discussions and realization of scientific community and people at large that finding alternative sources of energy is the only way to reduce the greenhouse gases. Scientists started looking to nature and technology for solutions. So started discussion of solar, wind, bio, tidal, nuclear and hydrogen energy as alternative to the fossil fuel.

The search for alternative energy sources is strongly rooted in the realization that the conventional energy sources are polluting and they are not renewable and thus limited. The central theme of all these activities is the human lifestyle.

Protection of the Environment and Climate, and their preservation for the generations to come is a demanding social, scientific and economical task. Utilization of renewable energy, efficient conversions of fossil fuel are not only environmentally and climatically beneficial, they also preserve the finite energy sources. The price jumps in the oil scenario, has surely made the scientific community know the importance of safe and secured energy supplies for the highly industrialized nations.

At one end, the rapid industrialization has led to increased use of fossil fuels such as coal, oil etc, to meet its power and steam requirement. For which, the developing nations like India are paying huge import bills putting stress on its economy. At other end, a naturally available energy sources such as solar, wind, biomass, biogas etc are not effectively used.

India has potential to generate 45,000 MW from wind energy, 19,000 MW from biomass energy, 15,000 MW from small hydro projects. In addition to it the urban areas in India produce @ 30 million of solid waste and 4400 Million cubic meters of liquid waste every year. The same can be exploited to generate power and meet a part of the ever increasing demand of urban areas. Therefore, the need of the hour is to conserve petroleum by its judicious use, substituting it by other resources wherever techno-commercially feasible and restricting its use only to the essential needs.

Solar cells were too expensive for small-scale electrical generation, so practical people turned to windmills.