Geothermal EnergyGeothermal energy is thermal energy generated &

stored in the Earth OR Geothermal energy is the natural heat from the Earth.

Geothermal Greek (geo), meaning earth, and (thermos), meaning hot.

The Geothermal energy of the Earth's crust originates from the original formation of the planet (20%) and from radioactive decay of minerals (80%).

Italy, New Zealand, USA, Japan, Mexico, Philippines, Indonesia with Largest capacity in the United States (3,086 MW),Philippines, and Indonesia.

Geothermal power stationsGeothermal power stations are similar to steam

turbine thermal power stations - heat from the earth's core is used to heat water or another working fluid.

The working fluid is then used to turn a turbine of a generator, thereby producing electricity.

The fluid is then cooled and returned to the heat source.

Several variations to this system existPumping up pre-existing heated water or

steam from below the earth’s surface as the source of water

As pumping surface water down to a heated area below the earth’s surface where it becomes heated and then pumped up again

Geothermal power station

Geothermal Electricity

Geothermal electricity is electricity generated from geothermal energy.

Most common technologies include Dry steam power plantsFlash steam power plants Binary cycle power plants

Dry steam power plants

Dry steam plants are the simplest and oldest design.

They directly use geothermal steam of 150°C or greater to turn turbines.

Dry steam power plants

Flash steam power plantsFlash steam plants pull deep, high-pressure hot

water and use the resulting flashed steam to drive turbines.

They require fluid temperatures of at least 180°C, usually more.

This is the most common type of plant in operation today.

In some cases, direct steam is available from the geothermal reservoir; otherwise the steam is separated and turbines are used for power generation.

Flash steam power plants

Binary cycle power plantsBinary cycle power plants are the most

recent development, and can accept fluid temperatures as low as 57°C.

The moderately hot geothermal water is passed by a secondary fluid with a much lower boiling point than water.

This causes the secondary fluid to flash vaporize, which then drives the turbines.

The thermal efficiency of this type plant is typically about 10-13%.

Binary cycle power plants

Environmental impactThe thermal efficiency of geothermal electric plants is low, around 10-

23%Fluids drawn from the deep earth carry a mixture of gases, CO2, H2S,

CH4 and NH3.These contribute to global warming and noxious smells if released.

Hot water from geothermal sources may hold in solution trace amounts of toxic chemicals, such as mercury, arsenic, boron, antimony, and salt.

Plant construction can adversely affect land stability. Enhanced geothermal systems can trigger earthquakes as part of

hydraulic fracturing. Capital costs tend to be high. Drilling accounts for over half the costs and exploration of deep

resources entails significant risks. Subsidence

AdvantagesRenewable , Cost free & Ecofriendly Geothermal power requires no fuel, immune to fuel cost

fluctuationsGeothermal has minimal land (404 square meters per

GWh )and freshwater (20 litres of freshwater per MW·h )requirements.

Geothermal power is highly scalable The emission intensity of existing geothermal electric

plants is on average 122 kg of CO2 per megawatt-hour (MW·h) of electricity, about one-eighth of a conventional coal-fired plant.

Geothermal power is Sustainable because the heat extraction is small compared with the Earth's heat content.

Geothermal power does not rely on variable sources of energy, unlike, for example, wind or solar, its capacity factor can be quite large .