Geothermal Power Plants

Now that we know some of the basics, let us dive deeper into geothermal and look at how steam and/or hot water generates electricity in 3 types of power plants:

  1. dry steam,
  2. flash steam, and
  3. binary cycle power plants.

These plants use the same hydrothermal resources (“hydro” = water & “thermal” = heat) and require the temperature of the resource to be between 300°F to 700°F. These resources can be geothermal reservoirs, hot water wells, or ground temperature.

Let’s now examine each of these power plants more closely.

  1. Dry Steam Power Plants. This power plant uses steam directly from a geothermal reservoir. This steam turns the turbine and generates electricity. The first geothermal power plant was a dry steam plant established in 1904 in Tuscany, Italy.
  2.  Flash Steam Power Plants. This power plant uses high-pressure hot water from the Earth’s crust and converts it to steam to drive the turbines. When the steam is cooled, it transitions to liquid. It returns to the Earth to be used again and again. Most of the geothermal plants in operation today are of this type.
  3. Binary Cycle Power Plants. This power plant transfers the heat from the hot water to another liquid. The heat causes the liquid to turn to steam that drives the turbines to generate electricity.

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Sources: U.S. Department of Energy.

On a smaller scale, say to power a building, one can implement a geothermal heat pump. The heat pump uses the fact that about 10 feet under the ground surface, the Earth is consistently between 50°F and 60°F. This means that in winter the ground is warmer than the air and in summer the ground is cooler than the air. The pump transfers the heat from the ground in the winter and reverses the process in the summer. This is a great way of keeping a constant temperature in a building year-round.


Source: U.S. Energy Information Administration.

Per the Environmental Protection Agency (EPA), geothermal heat pumps are the most energy-efficient, environmentally clean, and cost-effective systems for heating/cooling structures of any kind.

So how do these plants work exactly? They all use heated water or working liquid and when the steam passes through the turbine, the heat is converted to electricity in a generator through electromagnetic induction (a process where a conductor is placed in a changing magnetic field and that field flux produces a voltage across the conductor).

Poof! Electricity.

This electricity is then distributed through the grid to various access points (houses, schools, hospitals, etc.). For every one unit of energy used to power the system, three to four units are produced (since energy is conserved by not burning fossil fuels for heat).

For a quick visualization of this process, watch the brief video below!

Source: alternativeenergy1.

As we embark to adopt renewables as the norm, geothermal provides us with the an exceptional, reliable form of energy. If you have the option of getting some of your power through geothermal energy, do it! Start the revolution by asking your power provider for alternative energy. With such a clean, low-cost, and highly efficient system, it brings hope to the future of the power grid.

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