What is geothermal energy?
Geothermal energy is a process which utilizes thermal energy (heat energy) of the Earth to power turbines for the production of electricity on the power grid. This technology can be used on a variety of scales for national production of electricity or simply to provide additional power to a home on a smaller scale. This energy source is considered to be a renewable energy source since the Earth constantly produces heat internally through the circulation of magma and increased pressure in certain areas.
Where does the Earth’s thermal energy come from?
Thermal energy on our planet is produced initially at the Earth’s core where intense pressure forces rocks to heat up and melt creating magma. Magma, naturally lighter than the solid rocks contained in the layers above the core, finds every resource available to attempt to escape which creates thermal hotspots that can lead to formations of hot springs or volcanoes. Through the development of technology, this energy can be harnessed in the same ways that locomotive technology was created by using steam to power an engine.
How does geothermal power work?
When building a geothermal power plant, it is essential to first either find or create what is called a geothermal well. This is a pocket of water located in a hotspot within the earth that uses the natural thermal energy created to cause the heated water to evaporate or flow up a pipe to the power plant. From this stage there are three distinct processes which can be used to capture the energy to produce electricity. Both processes use a turbine which will be powered by the movement of particles heated from the geothermal well. The most common process used to mass produce electricity from geothermal energy is in the binary cycle power plant.
How is geothermal energy captured?
A binary cycle power plant is one which utilizes the geothermal energy available in the Earth to power turbines which in turn create electricity through a process known as hydrothermal convection. Hydrothermal convection is the process of which water is heated to a boiling point and is pushed towards the Earth’s surface from a geothermal well. There are three distinct processes currently in use by 28 nations in the world to produce power from thermal energy captured from the Earth. Currently the countries that use this energy technology are the United States, Philippines, Indonesia, Mexico, Ital, New Zealand, Iceland, Japan, El Salvador, Kenya, Costa Rica, Turkey, Nicaragua, Russia, Papua-New Guinea, Guatemala, Portugal, China, France, Ethiopia, Germany, Austria, Australia and Thailand. The three main ways in which energy can be captured are through dry steam, flash steam, and the binary cycle power plant.
Dry steam technology:
Dry steam technology uses water directly from the hydrothermal convection process to flow upwards into a pump which in turn uses the water to power a turbine that creates electricity. The steam is pumped from the heated well into a turbine system where it is used to spin the turbine blades and produce electricity. After the steam is used to power the turbine it is returned to the injection well where it is cooled back to its liquid state where it can be pumped back into the geothermal well for reuse in the cycle of creating electricity.
Flash steam technology:
Flash steam technology uses the same basic process as dry steam with the exception that the water it’s self is not used to power the turbines. The water gathered from the geothermal well is used only as a heating source the heat to evaporate a secondary fluid, one which must have a boiling point less than water, typically butane or pentane hydrocarbon. The secondary fluid is responsible for powering the turbines and is then sent through a cooling area which is made up of either cold air or cold water circulation systems to change it back to a fluid.
Binary cycle power plant:
A binary cycle plant uses a combination of both of the processes above to more efficiently capture the potential from the secondary agent for power. Hot water travels through a heat exchange which super heats the butane or pentane hydrocarbon causing it to spin the turbine to produce electricity. The working fluid is then passed through a cooling system to return it back to its original liquid state. Heated water then flows down into the injection well where it will be cycled back into the geothermal well for further use.
Sources for this article http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-geothermal-energy-works.html.Tags: energy resources, power plant, renewable energy