Geothermal energy is thermal energy generated and stored in Earth. Temperatures at the core may reach 6000°C. This heat is continuously radiated to the earth’s crust which helps to maintain ambient global temperatures of 6-15 °C, suitable for Heat Pumps with a CSP of up to 6. Rock and water is often heated up to 370 °C in geologically favorable locations, making it the most sustainable energy resource for heating and electricity production.
Hot springs have been used for bathing and for space heating since Aryans, Romans and Greek times. InManikaran Indian Himalayas food has been cooked in the HOT springs and distributed free to all visitors for the last 600 years. Since time immemorial Amchi (local geothermal traditional doctors) have been curing patients using medicinal properties of hot water (84°C) in the Higher Indian Himalaya. The Blue lagoons in Iceland have emerged as geothermal tourist destination. In modern times geothermal is now better known for electricity generation and heat pumps. The Larderello geothermal power plant in Italy has been successfully running for over 100 years 24 x 365 hours with nearly one GW base load power. Geothermal power plants use hot steam (Flash, Binary or Dry) from a reservoir to power turbines in USA, Indonesia, Philippines, Iceland and New Zealand. Enhanced geothermal systems (EGS) are also in the development stage in Australia and America which use heat from hot rocks to generate electricity by injecting water into hot dry rocks (HDR). The Krafla geothermal project successfully concluded after drilling into Magma at 2100 meters generating temperatures of more than 900°C capable of generating many Giga Watt (GW) of power. Agneyodgara (Lava Energy) and GEOCOGEN are advanced geothermal energy concepts aimed to produce plenty of GWh clean energy by tapping lava energy in geologically favorable environments.
Geothermal energy is seen as a most economical energy in present days. The International Geothermal Energy Association (IGA) has reported that 11,765 MW of installed geothermal power capacity in 24 countries and expect to generate 18,500 MW by 2015 from more than 700 plants. In 2010, the USA led the world in geothermal electricity production with 3,086 MW of installed capacity from 77 power plants. The Philippines is second with 1,904 MW followed by Indonesia, Mexico, Italy, New Zealand. Iceland has the highest percentage share of geothermal energy (4600 GWh) of their national electricity production. The country is planning to export the surplus geothermal energy to Scotland through submarine cables and later to Europe. Similarly, Africa has a great potential and initial experiments in the Kenya Rift Valley & Ethiopia have yielded good results. After the Fukushima Nuclear disaster the Japanese government was forced to shut down >40 nuclear plants and shift its focus to wind, solar and geothermal energy to meet its energy requirements. With a total estimated potential to the tune of 23 million kW Japan has identified 60 potential sites and will soon inaugurate its 1st geothermal power plant on the Southern island of Kyushu, in Kumamoto Prefecture, a region known for its natural hot springs and volcanic activity.
Geothermal holds the key to solve the energy problem of over 1 Billion population of India with its known geothermal potential of around 10,000 MW in peninsular and Himalayan regions. Gujarat, Delhi, Mumbai and Madras are potential geothermal sites in India due to their typical geological and tectonic conditions. Andaman and Nicobar have the potential to become a future Geothermal energy centre like Iceland. The historic TATTAPANI (Tatta means hot and Pani is water) geothermal site near Shimla in the Indian Himalaya will be submerged in the KOL dam reservoir in 2014. Puga geothermal field can provide green energy to army in China Border. There is urgent to frame a National Geothermal Policy for R&D investments in geothermal exploratory wells to provide green clean energy to the people.
The United Nations designated 2012 as “Year and Decade of Sustainable Energy for All” coupled with the International Energy Organizations commitments of achieving universal energy access by 2030. Geothermal Energy holds one of the golden keys to fulfilling these objectives. The future of this resource however depends on policy shift, drilling technology, energy prices and subsidies. The heat and electricity costs of 2 to 5 US cents per kWh can recover the investments in a few years. According to ISEO, geothermal solutions not only provide sustainable but also abundant Economical and SAFE energy for all by 2050.