An Overview of Geothermal Energy
To understand the history of geothermal energy, we must first understand what it is. At the center of the earth, the temperatures can reach extreme heats of up to 9,000 degrees Fahrenheit. The earth has many layers and as these layers come in contact with each other the heat from the deeper level conducts to the next level. For example, the layer closet to the earth’s core becomes hot from the intense heat of the core. In turn those layers will transfer heat to the layer above it. These layers also heat anything they touch, such as magma and water. While magma is usually not seen often on earth, with the obvious exception of volcanoes, hot water springs are found all over the earth. Not all water escapes the earth’s surface, however, and remains under the surface where drills can be used to penetrate to the hot water below.
It is said that ancient Romans as well as Native Americans used this hot water to treat ailments while some indigenous people of New Zealand have harnessed geothermal energy for hundreds of years. In a more recent sense, many island countries have been successfully using geothermal energy for a large portion of their energy needs. The first geothermal power plant opened in Italy in 1907, and its success has spawned great growth in the field. France has used geothermal energy extensively for decades to heat homes there.
Geothermal energy is what is known as a renewable energy source. That is to say, the products used to harness the energy are replaced or reused more than one time. In the case of geothermal energy, the hot water is “sucked up” to the geothermal power plant where either steam, water or both are used to spin a turbine, which of course produces energy. The water can then be pumped back down into the reservoir to be reheated and used again later. There are three types of geothermal plants:
1. Dry steam reservoir – almost exclusively uses steam to spin the turbine
2. “Flash” hot water reservoir – uses very hot water (temperatures ranging from about
300-700 degrees Fahrenheit) to spin turbine
3. Binary power plant – uses cooler (but still hot) water to transfer that heat to
another substance with a lower boiling point than water to produce steam and spin
The main pollutants that come from geothermal power plants are carbon dioxide and hydrogen sulfide. While these gases contribute highly to the greenhouse effect, they are found in much smaller numbers than their fossil fuel counterparts, in fact, geothermal plants usually only emit roughly 5% of the amount of these gases as do fossil fuel plants. Geothermal plants also take up much less land and...