Geothermal energy is the process of capturing energy from the heat within the Earth. Thermal energy is considered to be the energy that determines the heat of matter. When studying geothermal energy it is important to understand the geothermal gradient which is the variation in temperatures from the Earth’s core to it’s surface. Thermal energy is largely created through radioactive decay of materials in the Earth’s core. With the combination of pressure and heat rocks and minerals melt into what we know as magma or lava. Magma is pushed upward out of the Earth’s core since it is lighter than the dense solid rock contained in the outlying layers of the Earth.
The oldest form of geothermal energy was utilized by humans through hot springs. In Roman times this was done for heating purposes and the oldest known usage of this energy source was discovered in China dating back to the Qin dynasty. Today geothermal energy is used to generate electricity largely through steam production to capture the movement of turbines. It is applied in heating spaces, electricity production, water heating, distribution of heat, industrial usage and agricultural usage throughout the world. It is one of the most cost effective forms of energy and is a sustainable resource which can reduce the usage of fossil fuels through greater implementation of this power source.
Binary Cycle Power Plant
A binary cycle power plant can be used to operate both dry steam and flash steam power plants. During this process, a geothermal well contains water at heated temperature which is pumped into an exchange where a secondary fluid is contained. The secondary fluid used must have a lower boiling point than water and typically utilizes butane or pentane hydrocarbon. The heat of the water is used to turn the secondary fluid into a vapor which powers a turbine and is then ran through a condenser to return it back to it’s original state as a fluid. The heated water is then returned to an underground reservoir where it can be reused in the cycle.
How does geothermal energy work?
The first geothermal electric plants were constructed on the edges of tectonic plates where the heat levels are much higher than other parts of the Earth. To utilize this for the purpose of creating electricity for the power grid, the process starts by finding or creating a geothermal well which is a pocket of water trapped in a heated space below the Earth. The heat energy emitted from the Earth boils the water causing it to flow upwards where the process can be split off into two distinct techniques for a binary cycle power plant. The first technique is called dry steam which uses the direct steam from the water vapors to power turbines. The second process is called flash steam which uses the heated steam vapors to heat a secondary liquid, typically butane which then powers a turbine.