me165 1_week 8. geothermal energy

8/17/2019 ME165 1_Week 8. Geothermal Energy

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ME165-1ALTERNATIVE ENERGY RESOURCES

EngWeek-8 Geothermal Energy2015-2016 / 3T


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GEOTHERMAL ENERGY

•Geothermal Energy

• The word “geothermal” originates from the Greek roots “γη (gmeaning earth

, and “θερμος (thermos)”, meaning hot .

• Geothermal energy is thermal energy generated and stored i

• Thermal energy is the energy that determines the temmatter.

•

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

• The geothermal gradient, which is the difference in temperat

the core of the planet and its surface, drives a continuous conthermal energy in the form of heat from the core to the surfac


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GEOTHERMAL ENERGY

• Geothermal Energy (cont’d.)

•At the core of the Earth, thermal energy is created by radioaand temperatures may reach over 5000 degrees Celsius (9,0Fahrenheit).

• Heat conducts from the core to surrounding cooler rock. The hi

temperature and pressure cause some rock to melt, creating mconvection upward since it is lighter than the solid rock. The ma

rock and water in the crust, sometimes up to 370 oC (700 oF).• From hot springs, geothermal energy has been used for bathin

Paleolithic times and for space heating since ancient Roman tim

now better known for electricity generation. Worldwide, aboumegawatts (MW) of geothermal power is online in 24 countrie


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GEOTHERMAL ENERGY

A geothermal

power plant works bypumping water down a deep

injection well. The water heats up

and escapes into the production well

as steam or super-heated water.


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GEOTHERMAL ENERGY

•Enhanced Geothermal System

1. Reservoir2. Pump house

3. Heat exchanger

4. Turbine hall5. Production well

6. Injection well7. Hot water to district heating

8. Porous sediments

9. Observation well10. Crystalline bedrock


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GEOTHERMAL ENERGY


•Geothermal power is cost effective, reliable, sustainableenvironmentally friendly, but has historically been limite

near tectonic plate boundaries.

• Recent technological advances have dramatically expa

range and size of viable resources, especially for appli

as home heating, opening a potential for widespread e• Geothermal wells release greenhouse gases trapped d

the earth, but these emissions are much lower per energ

those of fossil fuels.


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GEOTHERMAL ENERGY


•As a result, geothermal power has the potential to help global warming if widely deployed in place of fossil fu

• The Earth's geothermal resources are theoretically more

adequate to supply humanity's energy needs, but only a

fraction may be profitably exploited.

•Drilling and exploration for deep resources is very expeForecasts for the future of geothermal power depend o

assumptions about technology, energy prices, subsidies,

rates.


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GEOTHERMAL ENERGY


• Polls show that customers would be willing to pay a littla renewable energy source like geothermal. But as a re

government assisted research and industry experience,

generating geothermal power has decreased by 25%

past two decades.

• In 2001, geothermal energy cost between two and tenkwh.


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GEOTHERMAL ENERGY

Installed Geothermal Electric Capacity

CountryCapacity (MW)

2007

Capacity (MW)

2010

Percentag

of nationa

productio

United States 2687 3086 0.3%

Philippines 1970 1904 27%

Indonesia 992 1197 3.7%

Mexico 953 958 3%

Italy 810 843 1.5%

New Zealand 472 628 10%

Iceland 421 575 30%

Japan 535 536 0.1%Iran 250 250

In 2010, the United States led the world in geothermal electricity p

3,086 MW of installed capacity from 77 power plants. The lar

geothermal power plants in the world is located at The Geysers, a gein California. The Philippines is the second highest producer, with

capacity online. Geothermal power makes up approximately 18%

electricity generation.


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GEOTHERMAL ENERGY

Station Capacity (MW) Commissioned Community Status

Bacon-Manito Geothermal Power Plant 150 Bacon, Sorsogon Operationa

Leyte Geothermal Production Field 710 Ormoc City, Leyte (province) Operationa

Makiling-Banahaw Geothermal Power Plant 4801979, 1980, 1984,

1996Brgy. Bitin, Bay, Laguna Operationa

Malitbog Geothermal Power Station 233 1996 Malitbog, Southern Leyte Operationa

Mindanao Geothermal Production Field 106 Kidapawan City, North Cotabato Operationa

Northern Negros Geothermal Production Field 49 NW of Kanlaon Volcano Operationa

Palinpinon Geothermal Power Plant 1931983, 1993 - 1994,

1995Valencia, Negros Oriental Operationa

Tiwi Geothermal Power Plant 275 1979 Tiwi, Albay Operationa

Partial List of Geothermal Power Plants in the Philipp

http://en.wikipedia.org/wiki/List_of_powe

http://en.wikipedia.org/wiki/List_of_power_plants_in_the_Philippines#Geothermalhttp://en.wikipedia.org/wiki/List_of_power_plants_in_the_Philippines#Geothermal


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GEOTHERMAL ENERGY

• Geothermal Exploration

• The exploration of the subsurface in search of viable active geotregions with the goal of building a geothermal power plant, whe

drive turbines to create electricity.

• Exploration methods include a broad range of disciplines includin

geophysics, geochemistry and engineering.

• Geothermal regions with adequate heat flow to fuel power plant

rift zones, subduction zones and mantle plumes. Hot spots are chafour geothermal elements:1. Heat Source - Shallow magmatic body, decaying radioactive elements or

from high pressures

2. Reservoir - Collection of hot rocks from which heat can be drawn3. Geothermal Fluid - Gas, vapor and water found within the reservoir4. Recharge Area - Area surrounding the reservoir that rehydrates the geoth


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GEOTHERMAL ENERGY

•

Phases of geothermal power development:Exploration and reconnaissance

Pre-feasibility

Feasibility

Detailed design and construction

Operations and maintenance


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GEOTHERMAL EXPLORATION STAGES

•Exploration and reconnaissanceThe fundamental purpose of the exploration and

reconnaissance phase is to determine if there exists

commercially exploitable geothermal resource.

The first task is to perform a desk study, which entai

collection and analysis of all available existing dataregarding the geothermal field and the environment

to define the resource and scope of the following ex

activities.


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• Exploration and reconnaissance (cont’d.)

The desk study is followed up by field work, which uincludes:

•Geological mapping of important geological fea

order to get acquainted to the geological structu

geothermal system•Geochemical analysis of fluids from surface man

or shallow wells if available to get indications on

reservoir temperatures


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• Exploration and reconnaissance (cont’d.)

Geophysical explorations, like resistivity measurem

gravity and seismic profiling where needed, to get

understanding of the subsurface features of the ge

resource

Drilling of shallow exploration wells (usually 50-30

measure temperature gradients in order to locate t

flow zone of hot fluids in the geothermal reservoir


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•Prefeasibility

If the results from the exploration phase are positive, thdevelopment moves to the pre-feasibility phase where t

exploration becomes more focused on the most favorab

Activities in the pre-feasibility phase may include:

• More focused geophysical exploration

•Drilling of slim wells (+300 m)

• Environmental impacts assessment

• Drilling of deep exploration well

• Fluid chemical analysis

• Production potential assessment

•Pre-feasibility data analyzed and reported


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•FeasibilityIn the feasibility phase, the commercial level of the geoth

resource is generally demonstrated by the following activ

• Environmental impact assessment

• Drilling of production/injection wells

• Fluid sampling and chemical analysis

• Well testing and well logging• Conceptual modeling

• Production potential assessment (reservoir modeling)

• Preliminary design of power plant and surface equip

• Feasibility data analyzed and reported


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•Detailed design and construction

If the geothermal project is feasible, power purchase aghave been reached and financing is secured, the projec

the detailed design and construction phase. Detailed de

constructions begins with the following activities:

• Production/injection wells and drilling platform desig

•Drilling of production/injection wells

• Infrastructure facilities design and civil works

• Detailed design of power plant and steam gathering

• Detailed design of power transmission lines and poin

determined


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•Detailed design and construction (cont’d.)

•Service providers contracted for detailed des

engineering, procurement, construction and pr

management

•Construction of the power plant and facilities

•Training of operators and commissioning


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•Operation and maintenance

•After commissioning, the geothermal power plant

render normal service of providing sustainable e

the clients.

•With normal maintenance and responsible reservmanagement and utilization, a geothermal powe

provide renewable energy to the clients for deca


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TYPES OF GEOTHERMAL SYSTEMS

•

There are essentially 3 types of geothermalsystems in commercial use in the world:

1) Dry steam plants

2) Flash steam plants

3) Binary plants


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1. Dry steam plants - Similar to conventional steam p


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• Dry steam plants

Old Faithful is a cone geyser located in Wyoming, in Yellowstone Natio

the United States. Old Faithful was named in 1870 during the Washbu

Doane Expedition and was the first geyser in the park to receive a nam

http://www.youtube.com/watch?v=X4zA_YPCyHshttp://www.youtube.com/watch?v=dAUlLQIj_wk

http://www.youtube.com/watch?v=X4zA_YPCyHshttp://www.youtube.com/watch?v=dAUlLQIj_wkhttp://www.youtube.com/watch?v=dAUlLQIj_wkhttp://www.youtube.com/watch?v=X4zA_YPCyHs


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•Dry steam plants (cont’d.)

•Steam plants use hydrothermal fluids that are primsteam.

•The steam goes directly to a turbine, which driv

generator that produces electricity.

•The steam eliminates the need to burn fossil fuethe turbine. (Also eliminating the need to transp

store fuels.)

•This is the oldest type of geothermal power plant.


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•Dry steam plants (cont’d.)

• It was first used at Lardarello in Italy in 1904. Sttechnology is used today at The Geysers in north

California, the world's largest single source of ge

electricity.

•

These plants emit only excess steam and very minamounts of gases.


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• Flash Steam Plants: Most

common type of geothermal

power generation plants in

operation today• Single flash plants: Hot water after

separation from the steam is

evaporated by using part of the power

and fed back to the steam plant.

• Double flash plant: The hot water isevaporated to steam a second time, just

as in single-flash plants.

• Multiple flash plants: The same is

repeated several times until all hotwater is used economically.


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•Flash and double flash cycle (cont’d.)

•Hydrothermal fluids above 360°F (182°C) can bflash plants to make electricity.

•Fluid is sprayed into a tank held at a much lowe

than the fluid, causing some of the fluid to rapid

vaporize, or "flash."•The vapor then drives a turbine, which drives a g

• If any liquid remains in the tank, it can be flashe

a second tank (double flash) to extract even mor


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• Binary cycle: The hot water is utilized in heat exchangers

to evaporate ammonia or freon in a closed Rankin cycle.


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•Binary cycle (cont’d.)

•

Most geothermal areas contain moderate-tempewater (below 400°F). Energy is extracted from th

in binary-cycle power plants.

•Hot geothermal fluid and a secondary (hence, "b

fluid with a much lower boiling point than water

through a heat exchanger. Heat from the geothecauses the secondary fluid to flash to vapor, whic

drives the turbines.


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•Binary cycle (cont’d.)

•Because this is a closed-loop system, virtually notemitted to the atmosphere.

•Moderate-temperature water is by far the more

geothermal resource, and most geothermal powe

in the future will be binary-cycle plants.


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GEOTHERMAL ENERGY

•Environmental Impact

•Gas emissions

•Chemical pollutants

•Equipment pollutions

• Land stability

• Land and water usage


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ENVIRONMENTAL IMPACT•Gas emissions

• Fluids drawn from the deep earth carry a mixture of ga

notably carbon dioxide (CO2), hydrogen sulfide (H2S), (CH4) and ammonia (NH3).

• These pollutants contribute to global warming, acid rain

noxious smells if released.

• Existing geothermal electric plants emit an average of

kilograms (270 lb) of CO2 per megawatt-hour (MW•h)electricity, a small fraction of the emission intensity of co

fossil fuel plants.

• Plants that experience high levels of acids and volatile

are usually equipped with emission-control systems to re

exhaust.


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ENVIRONMENTAL IMPACT

•Chemical pollutants

• In addition to dissolved gases, hot water from geotherm

may hold in solution trace amounts of toxic elements suc

mercury, arsenic, boron, and antimony.

• These chemicals precipitate as the water cools, and can

environmental damage if released.

• The modern practice of injecting cooled geothermal flui

into the Earth to stimulate production has the side benef

reducing this environmental risk.


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•Equipment pollutions

•Direct geothermal heating systems contain pumps

compressors, which may consume energy from a

source.

•This parasitic load is normally a fraction of the houtput, so it is always less polluting than electric h


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• Equipment pollutions (cont’d.)

• However, if the electricity is produced by burning fossil the net emissions of geothermal heating may be compa

directly burning the fuel for heat.

• For example, a geothermal heat pump powered by

from a combined cycle natural gas plant would prod

as much pollution as a natural gas condensing furnacsame size.

• Therefore the environmental value of direct geothermal

applications is highly dependent on the emissions intensi

neighboring electric grid.


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•Land stability

•Plant construction can adversely affect land stab•Subsidence has occurred in the Wairakei field in

Zealand.

• In Staufen im Breisgau, Germany, tectonic uplift o

instead, due to a previously isolated anhydrite lacoming in contact with water and turning into gyp

doubling its volume.


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• Land stability (cont’d.)

•Enhanced geothermal systems can trigger earthq

part of hydraulic fracturing.

•The project in Basel, Switzerland was suspend

because more than 10,000 seismic events mea

to 3.4 on the Richter Scale occurred over the f

days of water injection.


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•Land and water usage

•Geothermal has minimal land and freshwaterrequirements.

•Geothermal plants use 3.5 square kilometres (1.4

per gigawatt of electrical production (not capaci

32 square kilometres (12 sq mi) and 12 square k(4.6 sq mi) for coal facilities and wind farms resp

•They use 20 litres (5.3 US gal) of freshwater per

versus over 1,000 litres (260 US gal) per MW•h

nuclear, coal, or oil.


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GEOTHERMAL ENERGY - RENEWABILITY AND SUSTAINABILIT

•Renewability• Geothermal power is considered to be renewable because a

projected heat extraction is small compared to the Earth's he

• The Earth has an internal heat content of 1031 joules (3•101

About 20% of this is residual heat from planetary accretion,remainder is attributed to higher radioactive decay rates tha

the past.• Natural heat flows are not in equilibrium, and the planet is s

cooling down on geologic timescales.

• Human extraction taps a minute fraction of the natural outflo

without accelerating it.


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GEOTHERMAL ENERGY - RENEWABILITY AND SUSTAINABILITY

•Sustainability

• Geothermal power is also considered to be sustainable its power to sustain the Earth’s intricate ecosystems.

• By using geothermal sources of energy present generat

humans will not endanger the capability of future gene

use their own resources to the same amount that those e

sources are presently used.

• Further, due to its low emissions geothermal energy is co

to have excellent potential for mitigation of global war

REFERENCES


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REFERENCES

• Textbooks• Renewable Energy Technologies, Jean-Claude Sabonnadiere, 2009

•

Energy Conversion, D. Yogi Goswami, Frank Kreith, 2008• Power Plant Engineering, 3rd Edition, PK Nag, 2008, Tata McGraw Hill

• Web

• http://en.wikipedia.org/wiki/Geothermal_energy

• http://www.camelclimatechange.org/articles/view/160957/

• http://www.discoversolarenergy.com/solar/geothermal.htm

• http://www.mannvit.com/GeothermalEnergy/GeothermalDevelopment/

• http://energyalmanac.ca.gov/renewables/geothermal/types.html

• Youtube Videos• http://www.youtube.com/watch?v=Q_9dNx13f4U

• http://www.youtube.com/watch?v=BHSNBzHCvMI
http://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/wiki/Geothermal_energyhttp://www.camelclimatechange.org/articles/view/160957/http://www.camelclimatechange.org/articles/view/160957/http://www.discoversolarenergy.com/solar/geothermal.htmhttp://www.discoversolarenergy.com/solar/geothermal.htmhttp://www.mannvit.com/GeothermalEnergy/GeothermalDevelopment/http://www.mannvit.com/GeothermalEnergy/GeothermalDevelopment/http://energyalmanac.ca.gov/renewables/geothermal/types.htmlhttp://energyalmanac.ca.gov/renewables/geothermal/types.htmlhttp://www.youtube.com/watch?v=Q_9dNx13f4Uhttp://www.youtube.com/watch?v=Q_9dNx13f4Uhttp://www.youtube.com/watch?v=BHSNBzHCvMIhttp://www.youtube.com/watch?v=BHSNBzHCvMIhttp://www.youtube.com/watch?v=BHSNBzHCvMIhttp://www.youtube.com/watch?v=Q_9dNx13f4Uhttp://energyalmanac.ca.gov/renewables/geothermal/types.htmlhttp://www.mannvit.com/GeothermalEnergy/GeothermalDevelopment/http://www.discoversolarenergy.com/solar/geothermal.htmhttp://www.camelclimatechange.org/articles/view/160957/http://en.wikipedia.org/wiki/Geothermal_energy

me165 1_week 8. geothermal energy

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