Published on Sustainable Cities

Geothermal Energy

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For years, the thermal energy beneath the surface of the Earth has been used for many things. Bathing, agriculture, aquaculture, industrial or heating purposes, or even to generate power; the results are often impressive. The Earth’s structure radiates a constant flow of thermal energy outwards to the crust. This phenomenon is a natural, renewable source of heat which provides a substantial contribution to the mitigation of greenhouse gas emissions.

By accessing pockets of hot water or steam that exist naturally within the Earth’s crust to heat or power systems above ground, energy developed from other sources like coal and petroleum is reduced. Typically, power plants that use geothermal energy are located along tectonic plate intersections due to the higher temperature that exist beneath the surface. Boreholes are drilled and equipped with piping systems. Water is circulated through these pipes absorbing heat which is then used to power turbines.

For locations with a temperature gradient in the Earth’s crust of less than 100°C, geothermal resources are not generally recommended for power generation. Areas like these are better suited for district and residential heating systems. These systems use the stored heat beneath the ground to warm or cool air within buildings, as well as to supply hot water.

In Ontario, the temperature gradient beneath the surface of the Earth is relatively low. Because of this, there is not enough stored heat to efficiently generate electricity, but there is still enough for heating (and cooling) of buildings. At The University of Ontario Institute of Technology, my university, geothermal resources regulate heating and cooling for 8 buildings at the North campus. The system consists of 384 boreholes reaching depths of 213m; temperatures at this depth fluctuate between 8-12°C annually which allows for continual operation year round.

Indonesia has shown great success with geothermal power plants as a source of electricity generation. Due to their location along the tectonic plate intersections, they lie on top of a hot spot which produces a substantial amount of heat. Kenya also has a tremendous amount of potential for geothermal applications. Countries such as these have the ability to emerge as leaders in the technology in the near future.

When compared to other renewable and non-renewable methods of heating and power generation, geothermal resources allow for a much cleaner, more reliable, and sustainable production process. With more research, and enhancements in efficiency, geothermal energy has enormous potential. For developing countries, the world can rest a little easier knowing that as energy demands increase globally, the locations with the most potential for geothermal energy can contribute through clean, green, and more renewable energy methods.

This is sixth in a series of blogs on energy issues written by 4th year energy systems students from the University of Ontario Institute of Technology in Oshawa, Ontario. (See blog by Dan Hoornweg introducing the series.)

Photo credit: University of Ontario Institute of Technology

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