The earth’s interior is very hot because of the heat generated by the decay of radioactive particles. The heat so generated is used as an energy source called geothermal power. Geothermal power can be harnessed by either drilling the earth’s surface or by collecting hot water or steam in a geothermal reservoir.
The various geothermal power technologies used are:
1. Binary cycle power plants- In these, hot geothermal water is used to vaporize another fluid with a much lower boiling point. The vapor so formed drives turbines to generate electricity.
2. Enhanced geothermal systems- In these systems, wells are dug to the depth of hot rocks. A fluid is then heated from these hot rocks and is used to generate power.
3. Dry steam plants- These plants use geothermal steam to run turbines for the purpose of generating electricity.
4. Flash steam plants- In these plants, high pressure hot water are collected in low pressure tanks. The conversion of hot water into steam causes the turbines to rotate and generate electricity.
5. Direct Heat- Hot water near the earth’s surface is piped to keep buildings heated. This hot water can also be used to grow plants in a greenhouse, dehydrate onions, pasteurize milk and for fish farming.
6. District heating- These systems use hot water for heating buildings in communities.
7. Geothermal heat pump- The temperature at the upper ten feet of the earth’s surface is constant. Geothermal heat pumps are installed in buildings and consist of water pipes and heat exchangers. These are used to keep buildings warm in winters and cool in summers.
The geothermal power technologies help in the optimal utilization of geothermal power.