Geothermal Energy

Designed by Majd Khaleel

Objectives :

• Geothermal is very important because its power is reliable, sustainable, and environmentally friendly and it’s a type of Renewable energy

Outlines :

• 1- what is the geothermal energy ?

• 2-where does geothermal energy come from ?

• 3-how is electricity produced from geothermal energy & types of generators of electricity.

• 4-Geothermal’s Harmful Effects.

What is Geothermal Energy

• Geothermal means earth-heat. It is related to the thermal energy of Earth’s interior. On a large scale, the intensity of this thermal energy increases with depth, that is, the temperature of the Earth increases as we travel closer to its centre. A global average for Earth’s geothermal gradient (temperature increase with depth) is approximately 30°C/km. For example, if we merely removed the outer 3 km of Earth’s outer surface, it would be a sphere 5000°C at the core, and nearly hot enough to boil water on its surface. Earth contains an incredibly vast amount of thermal energy.

Where Does Geothermal Energy Come From

• Geothermal energy has two primary sources, primordial heat, and radioactive decay. Primordial heat is what resulted from the creation of Earth 4.5 billion years ago, when the energy and mass from colliding cosmic matter made Earth a large, hot piece of space debris

Where Does Geothermal Energy Come From

How is Electricity Produced from Geothermal Heat

• Geothermal energy uses the escaping heat from Earth’s core as a means to heat water into steam and produce electricity. By drilling deep into the Earth’s interior, we find temperatures suitably high to produce electricity.

How is Electricity Produced from Geothermal Heat

• Dry Steam Plants: These were the first type of plants created. They use underground steam to directly turn the turbines.

How is Electricity Produced from Geothermal Heat

• Flash Steam Plants: : These are the most common plants. These systems pull deep, high pressured hot water that reaches temperatures of 3600F or more to the surface. This water is transported to low pressure chambers, and the resulting steam drives the turbines. The remaining water and steam are then injected back into the source from which they were taken.

How is Electricity Produced from Geothermal Heat

• Binary Cycle Plants : This system passes moderately hot geothermal water past a liquid, usually an organic fluid, that has a lower boiling point. The resulting steam from the organic liquid drives the turbines. This process does not produce any emissions and the water temperature needed for the water is lower than that needed in the Flash Steam Plants (2500F – 3600F).

Geothermal’s Harmful Effects Brine can salinate soil if the water is not injected back into the

reserve after the heat is extracted.

• Extracting large amounts of water can cause land subsidence, and this can lead to an increase in seismic activity. To prevented this the cooled water must be injected back into the reserve in order to keep the water pressure constant underground.

• Power plants that do not inject the cooled water back into the ground can release H2S, the “rotten eggs” gas. This gas can cause problems if large quantities escape because inhaling too much is fatal.

• YouTube - How a Geothermal Plant Works.flv

Thank You