Friday, May 31

Geothermal Resources

Introduction to geothermal resources:

Geothermal energy is the heat from inside the earth, a kind of domestic energy which is reliable, cost effective and environmentally friendlier than other conventional sources of energy. It is released at an average heat flux of 60 mW/m2 by conduction. It is used for direct-heat use and electrical power generation.

Through production wells hot water is pumped up from the underground reservoir for generation of electricity, and then converted to steam by discharge of pressure. The steam is led into a turbine engine, which turns a generator. Remaining geothermal fluid is goes back into the reservoir to maintain its pressure.

Resources for geothermal energy

The global tectonic plates dictate the location of geothermal resources. Geo-dynamic processes like subsidence, sub-duction, uplift, fracturing result in geothermal features like volcanism and hydrothermal convection.

Common geothermal resources are:

A deep simple hot rock or magma body.

Heat carrying fluid.

Fractured or spongy rock.

Top rocks provide an insulating cover

The general geothermal resources need a fluid for heat transfer.

For direct-heat application, heat is extracted from the geothermal water at temperatures less than 120 o C which is used for greenhouse, home heating, vegetable drying and other small scale industries. The hot water spent, is used for direct application.

Technology and Resource Type

Geothermal resources  can be just liquid water, dry, a mixture of steam and water or mainly steam and varies in temperature from 30-350 o C. Water is the medium to transfer geothermal heat from the earth which is naturally occurring in most places but modern technologies extract this energy from hot dry rock resources. The temperature of the resource indicates the type of technologies required or its uses.

Conclusion to geothermal resources

Geothermal electric plants are built on the edges of tectonic plates as high temperature geothermal resources are available close to the surface

There are approximately 8,000 MW of generating and 12,000 MW of direct use geothermal resources world-wide.

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