GEOTHERMAL

ENERGYBALASUBRAMANIAN.MBALASUBRAMANIAN.M

ASHIQ AHAMED.CASHIQ AHAMED.C

BADRINATH.KBADRINATH.K

WORKING PRINCIPLE

What is it ……. ?

Geo = earthGeo = earth ++

Thermal = HeatThermal = Heat

CAUSE OF SOURCES• Earth's core maintains temperatures in excess of Earth's core maintains temperatures in excess of

5000°C5000°C• Heat gradual radioactive decay of elements Heat gradual radioactive decay of elements

• Heat energy continuously flows from hot core Heat energy continuously flows from hot core • Conductive heat flowConductive heat flow• Convective flows of molten mantle beneath Convective flows of molten mantle beneath

the crustthe crust..

Contd……Contd……

• Mean heat flux at earth's surface Mean heat flux at earth's surface

–16 kilowatts of heat energy per 16 kilowatts of heat energy per square kilometer square kilometer –Dissipates to the atmosphere Dissipates to the atmosphere

and space. and space. –Tends to be strongest along Tends to be strongest along

tectonic plate boundaries tectonic plate boundaries

Contd…Contd…

• Volcanic activity transports hot material Volcanic activity transports hot material to near the surfaceto near the surface–Only a small fraction of molten rock Only a small fraction of molten rock

actually reaches surface. actually reaches surface. –Most is left at depths of 5-20 km Most is left at depths of 5-20 km

beneath the surface, beneath the surface, • Hydrological convection forms high Hydrological convection forms high

temperature geothermal systems at temperature geothermal systems at shallow depths of 500-3000m. shallow depths of 500-3000m.

Geothermal ModelGeothermal Model

OPERATIONOPERATION

OUTLINE

DRY STEAMDRY STEAMDIRECT USEDIRECT USE

FLASH –SINGLE & DOUBLEFLASH –SINGLE & DOUBLEBINARYBINARY

HOT DRY ROCK HOT DRY ROCK EGSEGS

Dry Steam Schematic

Dry Steam Power Plants• ““Dry” steam extracted from natural reservoirDry” steam extracted from natural reservoir– 180-225 ºC ( 356-437 ºF)180-225 ºC ( 356-437 ºF)– 4-8 MPa (580-1160 psi)4-8 MPa (580-1160 psi)– 200+ km/hr (100+ mph)200+ km/hr (100+ mph)

• Steam is used to drive a turbo-generatorSteam is used to drive a turbo-generator• Steam is condensed and pumped back into the Steam is condensed and pumped back into the

groundground• Can achieve 1 kWh per 6.5 kg of steamCan achieve 1 kWh per 6.5 kg of steam– A 55 MW plant requires 100 kg/s of steamA 55 MW plant requires 100 kg/s of steam– Range 2.5 to 5 MWRange 2.5 to 5 MW

THE GEYSERS-CA-LARGEST DRY STEAM

Direct Use Technologies

• Geothermal heat is used directly rather Geothermal heat is used directly rather than for power generation than for power generation

• Extract heat from low temperature Extract heat from low temperature geothermal resources < 150 geothermal resources < 150 ooCC

• Applications sited near source (<10 km)Applications sited near source (<10 km)

Borehole Heat Exchange

This type uses This type uses one or two one or two

underground underground vertical loops vertical loops

that extend 150 that extend 150 meters below meters below the surface. the surface.

DISTRICT HEATING SYSTEM

Single Flash Steam

Single Flash Steam Power Plants

• Steam with water extracted from groundSteam with water extracted from ground• Pressure of mixture drops at surface and Pressure of mixture drops at surface and

more water “flashes” to steammore water “flashes” to steam• Steam separated from water Steam separated from water • Steam drives a turbine Steam drives a turbine • Turbine drives an electric generatorTurbine drives an electric generator• Generate between 5 and 100 MWGenerate between 5 and 100 MW• Use 6 to 9 tonnes of steam per hourUse 6 to 9 tonnes of steam per hour

Double Flash Schematic

Double Flash Power Plants

• Similar to single flash operation• Unflashed liquid flows to low-pressure tank –

flashes to steam

• Steam drives a second-stage turbine– Also uses exhaust from first turbine

• Increases output 20-25% for 5% increase in plant costs

Binary Cycle Schematic

Binary Cycle Power PlantsLow temps – 100Low temps – 100oo and 150 and 150ooCCUse heat to vaporize organic liquidUse heat to vaporize organic liquid

E.g., iso-butane, iso-pentaneE.g., iso-butane, iso-pentaneUse vapor to drive turbineUse vapor to drive turbine

Causes vapor to condenseCauses vapor to condenseRecycle continuouslyRecycle continuously

Typically 7 to 12 % efficientTypically 7 to 12 % efficient0.1 – 40 MW units common0.1 – 40 MW units common

Binary Plant Power Output

Combined Cycle Plants• Combination of conventional steam turbine Combination of conventional steam turbine

technology and binary cycle technologytechnology and binary cycle technology– Steam drives primary turbineSteam drives primary turbine– Remaining heat used to create organic vaporRemaining heat used to create organic vapor– Organic vapor drives a second turbine Organic vapor drives a second turbine

• Plant sizes ranging between 10 to 100+ MWPlant sizes ranging between 10 to 100+ MW• Significantly greater efficienciesSignificantly greater efficiencies– Higher overall utilizationHigher overall utilization– Extract more power (heat) from geothermal Extract more power (heat) from geothermal

resourceresource

Hot Dry Rock Technology

• Wells drilled 3-6 km into crustWells drilled 3-6 km into crust–Hot crystalline rock formationsHot crystalline rock formations

• Water pumped into formationsWater pumped into formations• Water flows through natural fissures Water flows through natural fissures

picking up heatpicking up heat• Hot water/steam returns to surfaceHot water/steam returns to surface• Steam used to generate powerSteam used to generate power

Hot Dry Rock Technology

Fenton Hill plant Fenton Hill plant

SITE SELECTION

CASE STUDY-------SABALAN , NW IRANCASE STUDY-------SABALAN , NW IRAN

KEY- R & D -WORKKEY- R & D -WORK

•Site Selection•Site Characterization•Reservoir Creation•Reservoir Validation•Interwell Connectivity•Reservoir Scale Up•Reservoir Sustainability

•Prioritization of sites for future EGS Prioritization of sites for future EGS development and estimating the size of development and estimating the size of the economic EGS resource. the economic EGS resource.

•Low-risk, economical EGS site selection Low-risk, economical EGS site selection and characterization capabilities. and characterization capabilities.

•Drilling, casing, and preparing the wells Drilling, casing, and preparing the wells for simulation and production. for simulation and production.

ENHANCED GEOTHERMAL SYSTEMSENHANCED GEOTHERMAL SYSTEMS

Tectonic Plate Movements

World Wide Geothermal Uses and Potential

RING OF FIRERING OF FIRE

Availability of Geothermal Energy

• On average, the Earth emits 16kW/kmOn average, the Earth emits 16kW/km22. However, this number can . However, this number can be much higher in areas such as regions near volcanoes, hot springs be much higher in areas such as regions near volcanoes, hot springs and fumaroles.and fumaroles.

• As a rough rule, 1 kmAs a rough rule, 1 km33 of hot rock cooled by 100 of hot rock cooled by 10000C will yield 30 MW C will yield 30 MW of electricity over thirty years. of electricity over thirty years.

• There is believed to be enough heat radiating from the center of the There is believed to be enough heat radiating from the center of the Earth to fulfill human energy demands for the remainder of the Earth to fulfill human energy demands for the remainder of the biosphere’s lifetime.biosphere’s lifetime.

Geothermal Site Schematic

Ground Structures

Performance vs. Rock Type