Geothermal power plants are facilities that use the heat from the earth to generate electricity. Geothermal power plants can be classified into three types: dry steam, flash steam, and binary cycle.
Dry steam power plants use steam from underground reservoirs to drive turbines directly. Flash steam power plants use high-pressure hot water from underground reservoirs to produce steam by lowering the pressure. Binary cycle power plants use low-temperature hot water from underground reservoirs to heat another fluid with a lower boiling point, such as isopentane, to produce vapor that drives turbines.
Isopentane is a type of hydrocarbon that has a branched chain of five carbon atoms. Isopentane has a low boiling point (28°C) and a high vapor pressure (0.7 MPa at 25°C). This means that isopentane can easily vaporize and expand when heated by the geothermal water, creating a high-pressure gas that can spin the turbines efficiently.
The advantages of using isopentane in geothermal power plants are:
- Isopentane has a higher thermal efficiency than water, meaning that it can produce more electricity from the same amount of heat.
- Isopentane has a lower freezing point than water, meaning that it can prevent the pipes and equipment from freezing in cold climates.
- Isopentane is non-corrosive and non-toxic, meaning that it can reduce the environmental impact and the maintenance cost of the power plants.
Isopentane is widely used in binary cycle geothermal power plants, especially in low-temperature geothermal fields, such as in Iceland, China, and the United States. Isopentane can help to utilize the geothermal energy more effectively and sustainably, contributing to a clean and renewable energy future.