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Geothermal Power Generation

Enhanced geothermal system

1. Reservoir 2. Pump house 

3. Heat exchanger 4. Turbine hall 

5. Production well 6. Injection well 

7. Hot water to district heating 

8. Porous sediments 

9. Observation well

10. Crystalline bedrock 

Geothermal Power Generation

Geothermal power plants use steam produced from reservoirs of hot water found a few miles or more below the Earth's surface to produce electricity. The steam rotates a turbine that activates a generator, which produces electricity.

There are three types of geothermal power plants: dry steam, flash steam, and binary cycle.

Dry Steam

Dry steam power plants draw from underground resources of steam. The steam is piped directly from underground wells to the power plant where it is directed into a turbine/generator unit. There are only two known underground resources of steam in the United States: The Geysers in northern California and Yellowstone National Park in Wyoming, where there's a well-known geyser called Old Faithful. Since Yellowstone is protected from development, the only dry steam plants in the country are at The Geysers.

Flash Steam

Flash steam power plants are the most common and use geothermal reservoirs of water with temperatures greater than 360°F (182°C). This very hot water flows up through wells in the ground under its own pressure. As it flows upward, the pressure decreases and some of the hot water boils into steam. The steam is then separated from the water and used to power a turbine/generator. Any leftover water and condensed steam are injected back into the reservoir, making this a sustainable resource.

Binary Steam

Binary cycle power plants operate on water at lower temperatures of about 225°–360°F (107°–182°C). Binary cycle plants use the heat from the hot water to boil a working fluid, usually an organic compound with a low boiling point. The working fluid is vaporized in a heat exchanger and used to turn a turbine. The water is then injected back into the ground to be reheated. The water and the working fluid are kept separated during the whole process, so there are little or no air emissions.

Currently, two types of geothermal resources can be used in binary cycle power plants to generate electricity: enhanced geothermal systems (EGS) and low-temperature or co-produced resources.

Puhagan Geothermal Plant

— Case study 

Total Capacity:

192.5 MW

Pipe Network:

35.9 KM

The Steps of EGS and Their Technologies

DRK and its partners in advancing geothermal energy propose a five-step decision process for the development of an EGS reservoir and electricity generation plant. The logical steps necessary to complete an economically-viable EGS operation are:

1.     Finding a site

2.     Creating the reservoir

3.     Completing a wellfield

4.     Operating the reservoir

5.     Operating the facility

Each step requires implementation of technologies specialized for the uniquely challenging geothermal environment. Currently available technologies are identified and assessed relative to their ability to satisfy the needs of EGS reservoir development. The adequacy of technology has been determined for both near- and long-term applications.

Investment Fundamental

We are looking for opportunities to invest and develop geothermal power plants:

 Capacity: 50 MW/year

 Total Investment: US$ 100-300 mm

 Projected Unleveraged Annual Cash Return on Investment: 10%