Geothermal energy is thermal energy generated and

stored in the Earth

The Geothermal energy of the Earth's crust originates

from the original formation of the planet (20%) and

from radioactive decay of minerals (80%).

EATRTH AS AN

ENERGY SOURCE

The earth's core maintains temperatures in

excess of 6000°K due to the heat generated by the

gradual radioactive decay of the elements it contains.

•Inner Core - The inner core is solid with a radius of about 1,220 km

and consists of about 80% Iron and 5% to 10% Nickel, with a

temperature of up to about 7,200 K

•Outer Core- The outer core, also mainly Iron and Nickel, is in a liquid

state and is about 2,260 km thick. Melted rock is also called Magma

•Mantle is about 2900 kms thick surrounding the core and

contains 83% of the volume and most of the mass of the Earth

•Lithosphere - The lithosphere is defined as the solid rocky region

about 100-200 km thick which spans the crust and the rigid upper

mantle•Crust - The Earth's crust occupies just 1% of the Earth's volume with a

thickness averaging just 15 km•The temperature at the Earth's surface is typically 25 °C

ENERGY USED FROM EARTH IS GENERALLY TWO TYPES

1. HEAT EXCHANGERS

2. POWER PLANT GENERATION

There are three types of systems used in power plants in power generation

1. Dry Steam Systems

2. Flash Steam Systems

3. Binary Cycle Power Plants

Dry Steam Systems

•Dry steam system is make use of direct steam

That is obtained from aquifer.

•This is by far the cheapest method of

generating electrical energy from

geothermal resources

•Superheated water at high

temperature and pressure is

available from many more hot

water aquifers as well as hot rock

systems.

•When the pressure is reduced the

water flashes to steam.

•The most common geothermal electricity generating plants are

currently flash generators

•The hot water circuit is

separated by Heat exchanger

with closed loop circuit of

turbine• The hot water gives up its heat

in the heat exchanger to a

working fluid

•Working fluid has low boiling

point and high vapour pressure

at low temperatures when

compared to steam

•working fluid is typically an organic compound such as

ammonia, butane, pentane or isopentane

•Working fluid circulates through the secondary side of the heat

exchanger where it vaporizes and the vapour is then used to rotate

a turbine in a conventional Rankin electricity generating plant

•Geothermal heat pumps are similar to ordinary heat pumps

•Instead of using heat found in outside air ,it uses heat found in

earth

•The earth's constant temperature is what makes geothermal

heat pumps one of the most efficient, comfortable

•winter it collects the Earth's natural heat through a series

of pipes, called a loop, installed below the surface of the ground or submersed in a pond or lake. Fluid circulates

through the loop and carries the heat to the house

•There, an electrically driven compressor and a

heat exchanger concentrate the Earth's

energy and release it inside the home at a higher temperature.

•In summer, the process is reversed

1.Vertical Ground Closed Loop

2. Horizontal Grounded closed Loop

3. Pond Closed Loop

Here are the typical loop

configurations

Vertical Ground Closed Loops

•Vertical holes 150 to 450 feet

deep are bored in the ground

and a single loop of pipe with a U-bend at the bottom is inserted

•Each Vertical pipe is connected to

Heat exchanger inside the house

•Vertical loops are generally more

expensive to install, but require less

piping

Horizontal Ground Closed

Loops

•In this a deep hole is trenched 3 to 6

feet below the ground and a series of

Parallel pipes are arranged and it is

trenched back

•It is most effective

Pond Closed Loops

•It is most economical when a home is

near a body of water such as a shallow

pond or lake.

•Fluid circulates underwater through

polyethylene piping in a closed

system, just as it does through ground

loops

•Since it is a closed system, it results in

no adverse impacts on the aquatic

system.

•Since a GeoExchange system burns no fossil fuel on-site

to produce heat, it generates far fewer greenhouse gas

emissions than a conventional furnace

•Total emissions in power plant electricity generation

are far lower than for conventional systems

•Carbon monoxide emission is far lower