The emissions of harmful impurities into the atmosphere are increasing, and geothermal energy can solve this issue due to its environmental friendliness. This article will explain how to generate electricity in a geothermal power plant.
What is geothermal energy?
About 3.5% of the geothermal potential is used to generate electricity and 0.2% to heat. As a result, the capacity utilization factor of modern geothermal power plants reaches 90%, which is 3-4 times higher than other renewable energy technologies. Currently, geothermal energy is used in 51 countries in power generation technologies. A significant increase in the capacity of geothermal power plants is due to environmental safety, significant economic efficiency, and high rates of installed capacity utilization.
The problem is that traditional types of fuel (oil, gas, coal) only become more expensive over time because they become exhaustible, so you need to look for an alternative to these types of energy. Geothermal energy is renewable. In other words, it is eternal. It can provide processing from salt water to fresh water and electricity, which will be converted from the geothermal waters of the Earth. Thus, the method of extracting such energy makes it possible to use it for many centuries and save on fuel and operation – only for repairs, preventive maintenance, and scheduled maintenance. The scope of such energy is quite wide. Depending on the temperature, geothermal energy can be used in the electric power industry and in industry, agriculture, balneology, and many other things.
Geothermal power plants – ways to use geothermal energy
Two main uses for geothermal energy are direct heat and electricity generation. Direct use of heat is the simplest and, therefore, the most common method. The direct use of heat is widespread in high latitudes at the boundaries of tectonic plates, for example, in Iceland and Japan. The water supply in such cases is mounted directly in deep wells. The resulting hot water is used to heat roads, dry clothes, greenhouses, and residential buildings. Generating electricity from geothermal energy is very similar to the direct-use method. The only difference is the need for a higher temperature (more than 150 0C).
Currently, there are three schemes for the production of electricity using hydrothermal resources:
- direct using dry steam,
- indirect with steam
- mixed production scheme (binary cycle).
The type of conversion depends on the state of the medium (steam or water) and its temperature. Dry steam power plants were the first to be mastered. Steam from the well is passed directly through the turbine/generator to generate electricity for them. Power plants with the indirect type of electricity generation are the most common. They use hot underground water (up to 182°C), which is pumped at high pressure into generator sets on the surface. Mixed geothermal power plants differ from the previous two geothermal power plants in that the steam and water never come into direct contact with the turbine/generator.
The future of geothermal electricity
Steam and hot water reservoirs are only a small part of geothermal resources. Earth’s magma and dry rock will provide cheap, clean, virtually inexhaustible energy once the appropriate technologies are developed. Until then, the most common geothermal electricity producers will be binary cycle power plants.
For geothermal electricity to become a key element of the US energy infrastructure, methods must be developed to reduce its production cost. The US Department of Energy is working with representatives of the geothermal industry to reduce the cost of a kilowatt-hour to $0.03-0.05. As a result, new geothermal power plants with a capacity of 15,000 MW are predicted to appear in the next decade.