Geo-Thermal Energy

Department of Electrical EngineeringAssam Engineering College, Guwahati-13

Introduction Geothermal energy originates from radioactive decay of minerals and from solar energy

absorbed at the surface. Geo-thermal energy is one of the renewable energy sources. It is very consistent, reliable, cost effective, eco-freiendly and it has the highest energy

density. Worldwide, geothermal plants have the capacity to generate about 10 GW of electricity as of

2007 and in practice supply 0.3% of global electricity demand.

Geo-thermal energy sources

Hydrothermal Convective

Systems

Geo-pressure resources

Petro-thermal sources

Magma Resourc

esVolcanoes

Dry-steam fields

Wet-steam fields

Hot-water fields

Geo-Thermal power plants Can be divided into two main groups, steam cycles and binary cycles.

The steam cycles allow the fluid to boil, and then the steam is separated from the brine and expanded in a turbine.

A binary cycle uses a secondary working fluid in a closed power generation cycle. A heat exchanger is used to transfer heat from the geothermal fluid to the working fluid.

Advantages of Geo-thermal energy:

Geothermal power production has a positive impact on local economies, and creates significantly more jobs per megawatt than natural gas.

Geothermal power has a smaller land footprint than most other energy sources, particularly when compared with other renewables.

Geothermal power has very low emission levels. Binary plants produce near-zero GHG emissions while flash and dry steam plants represent a significant reduction compared to fossil fuel based generation.

Geothermal power’s established history of consistent output demonstrates a level of reliability unmatched by other renewables and fossil fuel based generation.

Applications

Direct

District heating, Crop Drying, Greenhouse

heating, Water heating

Indirect

Hydrothermal Electricity generation

Environmental Impact Direct use and heating applications have almost no negative impact

on the environment. Geothermal power plants do not burn fuel to generate electricity, so

their emission levels are very low. They release less than 1 percent of the carbon dioxide emissions of a

fossil fuel plant. Geothermal plants use scrubber systems to clean the air of hydrogen

sulphide that is naturally found in the steam and hot water. Geothermal plants emit 97 percent less acid rain.

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