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.
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.
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: