Geothermal Energy Systems

Guided by:

Ar.Firoz Anwar

Conte

mpora

ry T

echnolo

gy

Presented by:

Md Waseem Reza

Mohd. Khalid Raza

M.Arch, I Sem.

(Building Services)

Direct

Industrial & Domestic heating

HVAC

Mineral recovery

Greenhouses

IndirectElectricity generation

Geothermal Energy

• Geothermal Energy is heat (thermal)

derived from the earth (geo).

•It is the thermal energy from the

earth's core, which is stored in the

rock in the earth's crust.

Def

init

ion

Appli

cati

ons

Adva

nta

ges

• Renewable

•Environment friendly

•Sustainable

•Cost effective

Worldwide use of Geothermal Energy for Direct useSource: www.geofund.info/uploads/images/geofund%20images/geothermal_energy_utilization.JPG

Lim

itati

ons: • Not every area has accessible

geothermal sources.

•Green house gases emission.

•Localized Depletion

Hot water spring Geothermal Power Plant

Presented by: Md Waseem Reza & Mohd khalid Raza Slide Number: 1.

Geothermal Energy Systems

• Systems that utilizes the thermal energy stored in

earth.

Pri

nci

ple • Earth behaves as a huge collector-

cum-storage medium.

• Beyond 4 m depth earth

temperature remains constant ( equal

to mean air temperature at surface),

since it absorbs only 50% of all solar

energy

Ways

of

tappin

g

Geothermal energy

indirect coupling

Earth air tunnel

Geothermal exchange systems

direct coupling

earth envelope

Geothermal GradientSource: http://www3.uakron.edu/geology/Foos/Energy/1geot9.gif&imgrefur

Slide Number: 2.

Earth’s Temperatures

• Architectural practice of using earth

against building walls.

•Passive solar & sustainable

architecture.

Def

init

ion

Direct coupling- earth envelopes

• Earth berming

•In-hill construction

•Underground/fully recessed

construction

Typolo

gy

• Taking advantage of the earth as a

thermal mass.

•Offering extra protection from the

natural elements

•Energy savings

•Efficient use of land in urban

settings

•Shelters have low maintenance

requirements

Adva

nta

ges

• Water seepage

•Internal condensation

•Bad acoustics

•Poor indoor air quality.

•Requires heavier construction than

conventional building techniques

Lim

itati

ons

Earth sheltering

In-hill construction

Earth berming

underground/fully recessed

Cross-section

Slide Number: 3.

• An active technique that applies geothermal energy in required purposes using ground source exchange.

Indirect coupling – Geothermal exchange systems

Ground Loop system Heat Transfer fluid Heat PumpAir distribution

system Com

ponen

tsW

ork

ing

Circulation of fluid through pipes buried in ground

Exchange of heat either-way ( from fluid to earth or vice-versa)

Electrically driven concentrates this energy & release it at desired

temperature

Distribution through various distribution systems

Slide Number: 4.

The earth connection is where heat transfer between the GSHP system and the soil occurs.

Ground loop system

Types

Ground loop system

Closed loop

Horizontal

Vertical

Slinky

Pond

Open loop

Well to Well

Slide Number: 5.

• Central heating and/or cooling system that pumps heat to or from the ground

Geothermal heat pump

Cla

ssif

icati

on Geothermal

heat pumps

Function based

Heating

Cooling

Domestic water heating

Ventilation

Drying

Heat recovery

Heat source based

Ground

Ground water

Surface water

Air

Exhaust air

Working fluid based

Unit construction

based

Brine/water

Water/water

Direct expansion/water

Air/water

Air/air

Compact, split

Installation location (indoor, outdoor)

Compressor heat pump

Absorption heat pump

Number of compression stages

Desuper heater

Absorption heat pump

Air to air

Water to water

Slide Number: 6.

Components – Geothermal heat pump

Work

ing compressor

Loop-to-refrigerant heat exchanger

controls

•It consists of-

Slide Number: 7.

Components – Heat Transfer Fluid & Distribution system

•It is the refrigerant that circulates throughout the loop

• The decision to use water or antifreeze(propylene glycol, denatured alcohol or methanol) in the loop system depends

on a number of factors, such as the type of loop system installed and local conditions.

•Most residential geothermal systems use conventional ductwork to distribute hot or cold air and to provide humidity

control.

•A few systems use water-to-water heat pumps with one or more fan-coil units, baseboard radiators, or under-floor

circulating pipes.

• Properly sized, constructed, and sealed ducts are essential to maintain system efficiency.

• Ducts must be well insulated and, whenever possible, located inside of the building's thermal envelope).

Work

ing s

yst

ems

Hydronic heating systems.

• Also known as forced air distribution systems

• Hot water is circulated through radiators or a system of in-floor pipes to provide heat.

Forced air system

• A fan in the heat pump blows over a fan coil and the heated or cooled air is circulated throughout the house or building.

• Most common as they tend to be the most economical and they also provide both heating and cooling functions.

Dis

trib

uti

on s

yst

em

Slide Number: 8.

Summary- Geothermal Exchange Systems

Vertical ground loop system

Vertical pipe connected to heat

pump

Heat pump

Slide Number: 9.

Summary- Geothermal Exchange Systems

Comparative with conventional systems

Same system can be used for more

cooling area

Low Tonnage requirement

Reduced capacityIncreased economy

Lesser run time of system

Reduced power consumption upto

20-30%

Lower operational costs

Increased economy

Slide Number: 10.

Comparison with conventional systems

Adva

nta

ges

Environmental benefits

Operating cost

Self sufficient

Non-flamability

Sustanibility

Retrofit

Multiple functions

Durable and highly reliable

Low Noise

Unobstrutive

Assured Availability

Dis

adva

nta

ges

High installation costs

Cumbersome Installation

Heavy machinery required

Space requirement for loops

Greater pay back period

Frost time difficulties in some countries.

Not every area has accessible geothermal sources.

Arc

hit

ectu

ral

Adva

nta

ges

Space saving benefits

Elevational considerations

Reduction in overall load requirement of building

Reduced ducting requirements

Overall low initial and running cost

Slide Number: 11.

Practical applications in India

The

India

n C

onte

xt

•In India ground sink temperature remains between 20-25˚C.

•Enough load temperature is not available.

•Practical use merely limited to precooling fresh air to be used by conventional air-conditioning system.

•The system may be effective in peak summers and winters but fails in monsoon.

•Refrigerant- based dehumidifiers/ chillers need to be used in addition.

•Not extensively used in India.

Slide Number: 12.

• A passive technique consisting of a tunnel for passage

of calculated amount of air for the purpose of HVAC of a

space using natural heat of the earth, 4 m below the

earth surface.

•Also known as ground- coupled heat exchanger or earth-

tube heat exchanger.

•Used for either partial or full cooling and/or heating of

facility ventilation air

Indirect coupling – Earth Air Tunnel

Earth Air

Tunnel

Open loop

System

Closed Loop

System

Combination system

Types

Space to be

conditioned Surface

Ove

rvie

wP

rinci

ple •Uses constant air temperature

below 4 m of earth’ surface.

•Air blown through long cement of

metal tubes buried in earth.

•Heat Dissipated through surface

contact.

•Conditioned air supplied to space

Earth Air Tunnel

4 m

Open System

Space to be

conditioned

Surface

U bend Earth Air Tunnel

Closed System

Space to be

conditioned

Surface

Earth Air Tunnel

Combination System

Slide Number: 13.

Indirect coupling – Earth Air Tunnel

InletInline fan (optional)

Filter

Concrete/plastic coated metal/ plastic

coated with antimicrobial layer

tubes acting as tunnel

Outlet Blower

Air Handling

Unit (optional)

Air distribution

system

Air exhaust system C

om

ponen

tsW

ork

ing

Fresh Air sucked in through inlet.

Inlet air filtered

(mechanically/ natural filters)

Air passed through the length of tunnel. Heat gained/ lost through

surface contact

Conditioned air supplied to AHU through blowers

AHU contains evaporative coolers(summers)/dehumidifiers

(monsoons)/ chillers/cooling pads.

Air Distribution, circulation and re-circulation of return air

Air Exhaust through solar chimneys/ exhausts

Schematics Earth Air Tunnel

Slide Number: 14.

Indirect coupling – Earth Air Tunnel

Effi

cien

cy

Efficiency

Surface Area available for contact

Length of tube

Diameter of tube

Soil Type Clayey Soil is most effective. Sandy soil is least

SeasonWorks best in dry summer

and winters

Soil Conditions

Depth of water table

Depth of tunnel

Surface conditions Shady, sunlit, wet, dry,

combination

Efficiency of EAT

Slide Number: 15.

Indirect coupling – Earth Air Tunnel

Adva

nta

ges

Cost saving

Reduces air pollution

Energy saver

Reduces green house gases

100% fresh air without recirculation

Retrofit

Durable

Low Noise

Unobtrusive

Assured Availability

High installation costs

Cumbersome Installation

Subject to climate

Need add-ons to achieve effective conditioning

Large space required

Frost time difficulties in some countries.

Not every area has accessible geothermal sources.

Long payback period

Lim

itati

ons

Slide Number: 16.

Indirect coupling – Earth Air Tunnel

Entire Scheme and passive

factors effecting itSlide Number: 17.

Practical application in IndiaN

IIT U

nive

rsit

y, N

eem

rana

, Raj

asth

an•EAT used for P.G. hostels and Academic

block.

•Tunnels cool outside air from 44/360C to 280C.

•18 tunnels to handle 2 Lac CFM

•Each Tunnel 90m long to handle 12000 CFM -18000 CFM

•8 air change/Hrs. in Peak Summer and 3 air change/Hrs. during Monsoon & Winter

•Displacement Ventilation for Proper Air Circulation

•Special AHUs for recooling & Dehumidifying air for each Tunnel.

Slide Number: 18.

TUNNEL LAYOUT ON SITESource: http://nma-design.com/green-school/index_htm_files/8%20Vinod%20Gupta%20-%20NIIT%20Campus.pdf

Indirect coupling – Earth Air Tunnel

RET

REA

T, G

ual

Pahari

•EAT used for south block living

quarters.

•Tunnels cool outside air from to 30-280C.

•4 tunnels to handle 6,000CFM

•Each Tunnel 70 m with 70 cm dia.

•4 fans 2 HPeach force air in.

•Solar chimney force air out.

•Supplemented by 10 TR dehumidifier and chillers.

Slide Number: 19.

Electricity Generation

There are 3 types of power plants:-

Dry steam power plant

Flash steam power plant

Binary cycle power plant

Slide Number: 20.

• Earth’s core heat

• Water → steam → drive electrical generators

• Turbines

• Area specific

• Geothermal energy is localized

Geothermal energy is simply power derived from the Earth's internal

heat. This thermal energy is contained in the rock and fluids beneath

Earth's crust. It can be found from shallow ground to several miles

below the surface, and even farther down to the extremely hot

molten rock called magma.

These underground reservoirs of steam and hot water can be tapped

to generate electricity.

Geothermal power plant

Most power plants need steam to generate electricity. The steam

rotates a turbine that activates a generator, which produces

electricity. Many power plants still use fossil fuels to boil water for

steam. Geothermal power plants, however, use steam produced from

reservoirs of hot water found a couple of miles or more below the

Earth's surface. There are three types of geothermal power

plants: dry steam, flash steam, and binary cycle.

Source http://geo-energy.org/Basics.aspx

Steam is produced directlyfrom the geothermal reservoir to run the turbines

that power the generator, and no separation is necessary because wells only

produce steam.

This is the oldest type ofgeothermal power plant. It was first used at Lardarello

in Italyin 1904.

Dry Steam Power Plant

Geothermally heated water under pressure is separated in a surface

vessel (called a steam separator) into steam and hot water (called “brine).

The steam is delivered to the turbine, and the turbine powers a

generator. The liquid is injected back into the reservoir.

Flash Power Plant

Slide Number: 21.

Source http://geo-energy.org/Basics.aspx

The geothermal water heats another liquid, such as isobutane or other organic

fluids such as pentafluoropropane, which boils at a lower temperature than water.

The two liquids are kept completely separate through the use of a heat

exchanger, which transfers the heat energy from the geothermal water to the

working fluid.

The secondary fluid expands into gaseous vapor. The force of the

expanding vapor, like steam, turns the turbines that power the generators. All

of the produced geothermal water is injected back into the reservoir.

Binary Power Plant

Slide Number: 22.

Source http://geo-energy.org/Basics.aspx

Environmental Impacts

• Land

– Vegetation loss

– Soil erosion

– Landslides

• Air

– Slight air heating

– Local fogging

• Ground

– Reservoir cooling

Seismicity (tremors)

Advantages of Geothermal Energy

Geothermal Energy is a renewable source of energy.

By far, it is non-polluting and environment friendly.

There is no wastage or generation of by-products.

Maintenance cost of geothermal power plants is very less.

Geothermal power plants don't occupy too much space and thus help in

protecting natural environment.

Unlike solar energy, it is not dependent on the weather conditions.

Slide Number: 23.

Disadvantages of Geothermal Energy

Only few sites have the potential of Geothermal Energy.

Most of the sites, where geothermal energy is produced, are far from markets or cities, where it needs

to be consumed.

There is always a danger of eruption of volcano.

Installation cost of steam power plant is very high.

There is no guarantee that the amount of energy which is produced will justify the capital expenditure

and operations costs.

It may release some harmful, poisonous gases that can escape through the holes drilled during

construction.

Slide Number: 24.

Summary- Geothermal Electricity Generation

Bibliography

•Energy efficient buildings in India, by Mili Majumdar, TERI, India, Ministry of

Non-conventional energy sources, pg. 115

•Performance evaluation and energy conservation potential of earth air tunnel

system coupled with non air- conditioned building : Building & environment by,

Kumar, R. Ramesh, S. Kaushik

•Geothermal heat pumps: a guide for planning & installing by Karl Ochsner,

Earthsean Publishers , U.K.

Books

Ref

erre

d:

• www. Wikipedia.com

•www.indiaarchitectureinfo.com

Web

site

s: