Geothermal energy is very clean source of power. It comes from radioactive decay in the core of the Earth, which heats the Earth from inside out and thus energy/power can be extracted owing to the temperarture difference between hot rock deep in the earth and relatively cool surface air or water. This requires that the hot rock be relatively shallow, so it is site-specific and can only be applied in geologically active areas.
It can be used in two ways
• Geothermal heating
• Geothermal electricity
As stated above, geothermal energy from the core of the earth is closer to surface in some area than in others. Where hot underground steam or water can be tapped and brought to the surface it may be directly used to heat or cool buildings or indirectly used to generate electricity by running steam turbines. Even otherwise, on most of the globe, the temperature of the crust few feet below the surface is buffered at a constant 7-14 degree Celsius, so liquid can be pre-heated or pre-cooled in underground pipelines, providing free cooling in the summer and heating in the winter by using heat pumps.
(Useful for UPSC General Studies, APPSC Group 1 Group 2 , Mains Material, Paper 1, Paper 4 Section 1 Section 2 Section 3, ROLE AND IMPACT OF SCIENCE AND TECHNOLOGY IN THE DEVELOPMENT OF INDIA, GENERAL AWARENESS WITH THE MODERN TRENDS IN LIFE SCIENCES, DEVELOPMENT & ENVIRONMENT PROBLEMS)