subject: Geothermal As A Future Sustainable Energy (2) [print this page] Geothermal As A Future Sustainable Energy (2)
Geothermal power plant is needed to utilize superheated fluids in surface through a turbine which transforms geothermal energy into mechanical energy. Steam is produced from superheated fluid and hit the blades to generate electricity.
There are three main types of geothermal power plants: dry steam, flash steam, and two-cycle power plant. In a dry steam, geothermal plant steam flows directly to turbine and spins a generator. Used steam from turbine output is then cooled and injected back into the ground. Currently, the dry steam power plant is less common because it needs a geothermal resource which produces steam.
The second type is a flash steam geothermal which employs a flash container. The superheated fluid comes from the ground. It is composed by water and steam. It flows into a flash container, which works to separate steam and water. Pressure of superheated fluid should be decreased at a constant enthalpy occurring in a flash container.
There are two products from a flash container: a residual fluid and high-pressure steam High-pressure steam flows into a turbine while residual fluid flows into a second flash container. It produces a medium pressure steam and residual fluid. The residual fluid flows to a flash separator and produces the low-pressure steam. All the pressure steam is delivered to turbine and spins the generator while a residual fluid is injected back into reservoir wells.
The binary cycle or two-cycle power plants are more popular and technically advance in geothermal power plant technology. The hot water from production wells flows to heat exchanger while then working fluids, called binary liquid, working in the other side of heat exchanger. The researcher said that isobutane is usually a choice of working fluids. These substances should never mix in heat exchanger, but the heat energy moves from hot water to working fluids.
