The demand for energy doubles every 14 years and is taken as one of the indicators of development of a country. India, with 16% of the world's population consumes only 1.5% of the total energy produced in the world, in comparison of USA which has 6.25 of the world's population and utilizes 33% of the energy produced. This gives us an idea of the low level of our development and should be an incentive for better utilization of our resources for generating more energy, so that we can meet our growing demands of energy. Even today, about 80% of our population continues to depend on fuel wood, dung and agricultural wastes. We know that non-renewable sources of energy such as fossil fuels, coal and petroleum, are not going to last for long. Forests are also being depleted at a fast rate due to indiscriminate felling of trees. It has become, therefore, necessary to think alternative, non-conventional sources o energy. Some of these sources of energy are discussed here.

Solar Energy

The energy we get today from the fossil fuels like coal, is in reality sun's energy, trapped in plants millions of years ago. Plants make their food and grow by using solar energy for photosynthesis. Millions of years ago, huge forests got buried in the earth's crust and they got transformed into coal and oil under great pressure and temperature into coal and oil. Accordingly coal and oil are called fossil fuels.

However, nowadays, we have learnt to harness solar energy for various purposes. Solar energy can be used directly to give us hot water during winter or run a refrigerator. It can be used, for room heating in colder regions. Solar energy can be used with the help of 'Photo Voltaic Cells" for producing electricity for driving vehicles and for illumination. In a desert like Rajasthan solar energy, received at the earth surface is recorded200 watts per square meter per hour.