By, N Venkata Srinath, 1st Yr MS Power Systems. GEOTHERMAL By, N Venkata Srinath, 1st Yr MS Power Systems.

Geothermal Heat in the interior of the earth Greek originated. Geo-earth and thermal-heat. Temperature rise 20-30°/Km . Geothermal effects can be visualized as Hot gasses Hot spring Geysers -A spring that discharges hot water and steam Volcano

Technologies Aquaculture Spas Desalination Geothermal heat pump/District heating Industry Power Generation

Aquaculture Geothermal aquaculture, the ‘farming’ of water-dwelling creatures. Uses natural warm water to speed the growth of fish. Europe, USA, China and Japan. Catfish, Tilapia, Eels and Alligators.

Spas A health resort near a spring. A place of business with equipment and facilities for exercising and improving physical fitness.

Desalination Geothermal desalination is a proven process under development for the production of fresh water using heat energy. It requires less maintenance than reverse osmosis membranes.  In 1998 Douglas Firestone Aquagenesis from Nevada has began working with evaporation/condensation air loop water desalination.

Geothermal heat pump/District heating A geothermal heat pump or ground source heat pump (GSHP) is a central heating. The first successful commercial project was installed in the Common wealth Building (Portland, Oregon) in 1946.

Industry Geothermal energy is used by industries like food processing for pasteurizing , timber, leather manufactures, paper and dying .

Power generation Geothermal power is the power extracted form the heat stored in the earth. Types of technologies for locating geothermal reservoirs Magnetotelluric Electric Vacuum

How geothermal is an alternative/renewable Alternative: Instead of fossil fuels, we are using earth’s heat to generate steam. Renewable: The rate at which its heat is reducing is less than the rate it is increasing due to radioactive decomposition.

Different types of power generations Flash steam plants. Dry steam plants. Binary power plants. Hybrid power plants.

Flash steam plants Suitable for the reservoirs which cannot generate the steam 150°c. Most geothermal power plants operating today are ‘Flash steam’ power plants. Hot water from production wells is passed through one or two separators where, released from the pressure of the deep reservoir, part of it flashes (explosively boils) to steam.

Dry steam plant Reservoirs which can generate steam of temperature 180-350°c. This geothermal reservoirs produce mostly steam and very little water. Here, the steam shoots directly into the turbine.

Binary power plants. The geothermal water is passed through one side of a heat exchanger. where the heat is transferred to a second liquid, called a working fluid, in an adjacent separate pipe loop. The working fluid boils to vapour (like steam) powers the turbine generator. The geothermal water passes only through the heat exchanger and is immediately recycled back into the reservoir.

Binary power plants are generally more expensive to build than steam-driven plants. Advantages: The working fluid (usually isobutene or isopentane) boils and vapour’s at a lower temperature than does water. The binary system uses the reservoir water more efficiently. Binary power plants have virtually no emissions.

Hybrid power plant In Hybrid power plants, flash and binary processes are combined. An example of such a hybrid system is in Hawaii, where a plant provides about 25% of the electricity used on the Big Island. World 1st geothermal plant(Dry steam power plant) was built in 1904 at Larderello in Tuscany Italy which can give supply for 5 bulb. 1911 250kw power plant was built in devil valley which was destroyed in world war II. Rebuilt and expanded, still serving today.

Disadvantages Geothermal heat is extracted from deep within the earths surface, and this is the main disadvantage concerning finding a suitable location. To lay pipe lines, it has to dig for several feet's. Too expansive to bore.

Indian Scenario In India 1970 MNRE has started Hot Spring Committee . Other survey committees are NGRI, GSI. In India total potential is 6000 – 10,000MW There are 340 potential cites. The most promising provinces are    i)The Himalaya,  ii) Sohana,  iii) Cambay,   iv)  Son-Narmada-Tapi (SONATA) and v) The Godavari.

India’s first Geothermal plant was installed at Parbati Valley Manikaran (Himachal Pradesh) in 1992. India has collaborated with Iceland for Geothermal Technology in 2007. NTPC combined with Mitsubishi(Japan) in 2009 to built a 25MW power plant in Gujarat. MNRE planned to built a 1MW power plant at puga (Ladakh district, J&K) Tattapani region (Madhya Pradesh) where the installation of a 20MWe binary plant has been planned.

References Magnetotelluric Dept, NGRI, Hyderabad. http://mnes.nic.in/ http://www.clean-energy-ideas.com/ http://www.digtheheat.com/geothermal/ http://en.wikipedia.org/