GEOTHERMAL POWERPLANT BY GROUP 12
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Polytechnic University of the Philippines
College of Engineering
Department of Civil Engineering
Academic Year 2023-2024
A WRITTEN REPORT IN
ENGINEERING UTILITIES 2
Group 12 presents:
GEOTHERMAL POWERPLANT
Submitted by:
Camano, Roarke Johann A.
Fermia, Aloha Joy B.
Pacatang, Michael Angelo B.
Sunga, John Henry G.
Submitted to:
Morales, Armingol
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Geothermal Energy
The Word Geothermal comes from the Greek word ‘geo’ meaning earth and ‘therme’ means heat.
Geothermal energy is a renewable energy source derived from the natural heat of the Earth's
interior. This heat originates from the planet's formation over 4 billion years ago, the decay of
radioactive isotopes, and the heat generated by the gravitational forces exerted by the moon and
the sun. Geothermal energy is harnessed by tapping into underground reservoirs of steam and
hot water, which can be found near tectonic plate boundaries or in regions with volcanic activity.
Wells are drilled into these reservoirs to bring the hot water and steam to the surface, where they
can be used to drive turbines connected to electricity generators, or to provide direct heating. This
energy source is considered sustainable and environmentally friendly because it produces
minimal greenhouse gas emissions compared to fossil fuels and has the potential to provide a
continuous supply of energy.
Geothermal Power Plant
Geothermal power plants draw fluids from underground reservoirs to the surface to produce
heated material. This steam or hot liquid then drives turbines that generate electricity before it is
reinjected back into the reservoir.
There are three main types of geothermal power plant technologies: dry steam, flash steam, and
binary cycle.
Types of Geothermal Power Plant
Dry Steam Power Plant
A dry steam power plant is a type of geothermal power plant that directly utilizes steam from
geothermal reservoirs to generate electricity. It is called "dry steam" because it uses steam that
is almost entirely free of water droplets, unlike wet steam which contains a significant amount of
liquid water. In this type of plant, wells are drilled into underground geothermal reservoirs to tap
into the steam, which is then piped directly from the wells to a turbine. The force of the steam
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spins the turbine, which is connected to a generator that produces electricity. After passing
through the turbine, the steam is condensed back into water and reinjected into the underground
reservoir to be reheated and reused.
Flash Steam Power Plant
A flash steam power plant is the most common type of geothermal power plant and works by
using high-pressure hot water from geothermal reservoirs. When the hot water is brought to the
surface, the drop in pressure causes it to rapidly vaporize, or "flash," into steam. This steam is
then directed to spin a turbine connected to a generator, producing electricity. The remaining
water that does not flash into steam, along with the condensed steam, is usually reinjected into
the reservoir to sustain the pressure and ensure the longevity of the geothermal resource. Flash
steam plants can operate with geothermal fluids at temperatures ranging from about 150°C to
370°C.
Binary-Cycle Power Plant
A binary cycle power plant is designed to utilize lower temperature geothermal resources, typically
in the range of 85°C to 170°C. In a binary cycle plant, geothermal water is passed through a heat
exchanger where it transfers its heat to a secondary fluid with a lower boiling point, such as
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isobutane or pentane. This secondary fluid vaporizes and the vapor is used to turn a turbine
connected to a generator, producing electricity. The cooled geothermal water is then reinjected
into the reservoir, and the secondary fluid is condensed and reused in a closed loop. This process
allows for the exploitation of geothermal resources that are not hot enough for direct steam
production, making binary cycle plants a versatile and widely applicable technology for
geothermal energy generation.
Geothermal Resources
Geothermal resources are categorized based on temperature and usability:
1. Hydrothermal Resources: Common near volcanic regions, containing hot water and
steam in porous rock formations, suitable for conventional geothermal power plants.
2. Geopressured Resources: Found in sedimentary basins, these resources are under high
pressure and can harness both geothermal water and natural gas.
3. Hot Dry Rock (HDR) Resources: Found at greater depths, requiring Enhanced
Geothermal Systems (EGS) to inject water and generate electricity.
4. Magma Resources: Located at extreme depths with potential for high-temperature steam
production, though technical challenges remain in harnessing this resource effectively.
Global Distribution and Leaders
Geothermal resources are concentrated around the 'Ring of Fire,' encircling the Pacific Ocean.
Leading countries in geothermal energy production include the United States, Indonesia, the
Philippines, and Iceland, with Iceland notably utilizing geothermal energy extensively for heating
and electricity.
Trivia and Historical Context
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The first known use of geothermal energy for power generation dates back to 1904 in
Larderello, Italy.
The Geysers in California is the world's largest geothermal field, showcasing the longevity
and scalability of geothermal power.
Iceland leads in geothermal utilization, heating 90% of its homes and generating a quarter
of its electricity from geothermal sources.
Geothermal Power Plant Technology:
Geothermal power plants utilize the Earth's internal heat to generate electricity by converting
thermal energy from underground reservoirs into mechanical and electrical energy. This report
explores the types of geothermal power plant technologies, drilling techniques, essential tools,
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environmental impacts, sustainability considerations, and economic aspects associated with
geothermal energy production.
Types of Drilling Techniques
1. Rotary Drilling
Rotary drilling is a technique that uses a rotating drill bit to bore through the Earth's subsurface.
This method is widely used in geothermal energy exploration as well as in oil and gas drilling. The
rotating bit is driven by a drill string, a series of connected pipes that extend from the surface down
into the borehole. The rotation of the drill bit cuts and crushes the rock, allowing for the creation
of a deep, stable well. Drilling fluids, or "mud," are often circulated through the drill string and
back up the borehole to cool the bit, remove cuttings, and stabilize the well walls. Rotary drilling
is effective for drilling through a variety of rock formations and is capable of reaching significant
depths.
2. Direct Drilling
Direct drilling, also known as down-the-hole (DTH) drilling, involves a drill bit attached directly
to the end of the drill pipe. In this method, compressed air or fluid is used to drive a hammer located
at the bottom of the hole, immediately behind the drill bit. The hammer's rapid impact fractures and
breaks the rock, allowing the bit to advance. The cuttings are then lifted to the surface by the air or
fluid used to drive the hammer. Direct drilling is especially effective in hard rock formations and
is commonly used in geothermal drilling due to its ability to penetrate tough geological layers
efficiently.
3. Percussion Drilling
Percussion drilling, also known as cable tool drilling, is an older drilling technique that involves
repeatedly raising and dropping a heavy drill bit to fracture and pulverize the rock at the bottom of
the borehole. The drill bit is attached to a cable or drill string, which is lifted and dropped by a
mechanical system on the drilling rig. The broken rock fragments, or cuttings, are periodically
removed from the hole using a bailer or similar tool. While slower and less efficient than rotary
drilling, percussion drilling can be useful in certain geological conditions where other methods may
struggle.
4. Air Drilling
Air drilling uses compressed air instead of drilling mud to circulate and remove cuttings from the
borehole. In this technique, compressed air is pumped down the drill string and exits through the
drill bit, lifting the cuttings to the surface. Air drilling is particularly advantageous in areas where
water is scarce or where maintaining the stability of the borehole with drilling mud is challenging.
It is also faster than mud drilling in certain rock formations and is useful for drilling in dry, hard
rock conditions.
5. Mud Rotary Drilling
Mud rotary drilling is a common technique in geothermal and oil and gas drilling that uses a
circulating fluid, known as drilling mud, to facilitate the drilling process. The mud is pumped down
the drill string, exits through the drill bit, and returns to the surface carrying the cuttings with it.
The drilling mud serves several purposes: it cools and lubricates the drill bit, removes cuttings from
the borehole, stabilizes the well walls, and prevents blowouts by controlling subsurface pressures.
Mud rotary drilling is effective in a wide range of geological formations and is widely used for its
ability to maintain well stability and control during the drilling process.
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Examples of Drilling Tools
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Drill Bits: Includes roller-cone bits, PDC bits, and fixed-cutter bits.
Drilling Rigs: Structures housing drilling equipment like rotary rigs and top-drive rigs.
Drill Pipes, Drilling Mud, Casing, BOPs: Essential for well stabilization and safety
during drilling operations.
Environmental Impact and Sustainability
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Environmental Benefits: Low greenhouse gas emissions and renewable nature of
geothermal energy.
Challenges: Potential for air and water pollution, waste disposal issues, and impacts on
local ecosystems.
Emissions Mitigation: Strategies involve capturing and treating gases like hydrogen
sulfide and carbon dioxide.
Land Use and Water Consumption: Requires careful management to minimize conflicts
with other land uses and water resources.
Sustainability: Relies on responsible development practices to ensure long-term resource
availability.
Economic Aspects
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Cost of Production: High upfront costs for drilling and infrastructure, offset by low
operational and maintenance costs.
Comparison with Other Sources: Generally more cost-effective over time compared to
fossil fuels and some renewables, though initial investment can be higher than wind or
solar.
Financial Incentives: Governments offer subsidies to encourage geothermal energy
development.
Market Trends: Growing market driven by advancing technology and increasing demand
for sustainable energy sources.
Geothermal energy has emerged as a significant contributor to global energy solutions, harnessing
the Earth's heat to generate electricity sustainably. This report examines top geothermal energy
facilities globally, technological advancements, environmental challenges and solutions,
innovations in geothermal technology, and the role of policies and regulations in promoting its
development.
Top 10 Geothermal Energy Power Plants Worldwide
1. The Geysers Geothermal Complex, USA: Located in California, with 900 MW capacity,
powering nearly a million homes.
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2. Larderello Geothermal Complex, Italy: Established in 1913, 769 MW capacity, a
pioneer in global geothermal power.
3. Cerro Prieto Geothermal Power Station, Mexico: Situated in Northern Mexico, 720
MW capacity, showcasing unique geological features.
4. Makban Geothermal Power Complex, Philippines: Spanning Laguna and Batangas
provinces, 458 MW capacity, pivotal for Philippine energy.
5. Salton Sea Geothermal Plants, USA: Addresses soil erosion challenges in Southern
California, producing 340 MW.
6. Hellisheidi Power Station, Iceland: Utilizes volcanic resources for 303 MW electricity
and 400 MW thermal energy.
7. Tiwi Geothermal Complex, Philippines: Contributing over a quarter of the nation's
electricity, with six operational units since 1979.
8. Malitbog Geothermal Station, Philippines: Largest single-site installation globally,
232.5 MW capacity on Luzon Island.
9. Wayang Windu Geothermal Plant, Indonesia: Managed by Star Energy, covering 40 sq
km with 227 MW capacity.
10. Darajat Geothermal Facility, Indonesia: Located in Garut’s Pasirwangi District, 259
MW capacity, significant for Indonesia’s energy landscape.
Challenges Faced and Solutions Implemented
1. Resource Exploration and Assessment: Addressed through advanced geological surveys,
seismic imaging, and exploration drilling.
2. Scaling and Corrosion: Managed with corrosion-resistant materials, chemical treatments,
and monitoring systems.
3. High Initial Investment Costs: Mitigated by technological innovations, financing
mechanisms, and enhanced plant efficiency.
4. Environmental Impacts: Mitigated through rigorous monitoring, reinjection techniques,
and environmental best practices.
5. Resource Depletion and Sustainability: Managed with improved reservoir management
and Enhanced Geothermal Systems (EGS) technologies.
6. Location-Specific Challenges: Addressed through adaptive management and tailored
plant designs.
7. Grid Interconnection and Energy Storage: Advanced with grid infrastructure
development and energy storage solutions.
Innovations and Advancements in Geothermal Technology
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Enhanced Geothermal Systems (EGS): Artificially enhances geothermal reservoirs using
hydraulic fracturing.
Binary Cycle Power Plants: Utilize closed-loop systems for efficient heat exchange.
Super-Hot Rock Technology: Explores supercritical CO2 turbines for enhanced
efficiency.
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Direct Use Applications: Utilizes geothermal energy for heating and cooling directly.
Environmental Innovations: Reinjects cooled fluids and utilizes emissions for
sustainability.
Geothermal Energy Policy and Regulations
National Policies:
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Financial Incentives and Subsidies: Grants, tax credits, and subsidies support geothermal
development.
Feed-in Tariffs (FiTs): Premium rates for geothermal electricity stimulate investment.
Renewable Portfolio Standards (RPS): Mandates promote renewable energy
procurement.
Regulatory Support: Streamlined processes expedite project development.
Research and Development Funding: Government funds drive technological
advancements.
International Policies and Agreements:
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International Climate Agreements: Support transition to low-carbon energy sources.
Multilateral Development Banks (MDBs): Provide funding for geothermal projects in
developing countries.
Technology Transfer and Cooperation: Facilitate knowledge sharing and capacity
building.
Global Geothermal Alliance (GGA): Promotes global deployment of geothermal energy.
Licensing and Regulatory Framework
Ensures safe and sustainable development through permits, EIAs, and compliance with standards.
Role of Government and Private Sector
Governments provide frameworks and incentives; private sector drives innovation and operational
efficiency.
Challenges
1. High Initial Cost: Geothermal power plants entail significant upfront costs, primarily due
to equipment-intensive installation procedures. As of 2020, installation costs rose to $4,468
per kW, making it the second most expensive renewable energy type after solar power.
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2. Resource Depletion: Extraction of geothermal fluids can deplete natural reservoirs faster
than they replenish, posing sustainability challenges. Reinjecting cooled fluids back into
reservoirs helps mitigate this imbalance but requires careful management.
3. Release of Harmful Gases: Geothermal sites may release toxic gases during drilling.
Proper plant design and operational protocols are essential to contain and manage these
emissions effectively.
4. Reinjection Challenges: The process of reinjecting cooled fluids underground to maintain
reservoir pressure is crucial but presents technical and logistical challenges, including
managing fluid chemistry and reservoir stability.
Potential Breakthrough
Enhanced Geothermal Systems (EGS): EGS represents a transformative approach to geothermal
energy by artificially creating or enhancing reservoirs deep within the Earth's crust. This method
involves hydraulic fracturing to stimulate heat extraction from hot rock formations not naturally
suitable for traditional geothermal plants. EGS can utilize existing oil and gas wells, repurposing
infrastructure for sustainable energy production.
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Key Advantages: Offers reliable baseload energy, reduces reliance on fossil fuels, and
provides continuous power generation. EGS is scalable and has the potential for
widespread adoption as technology improves.
Challenges: Requires identifying suitable geological formations, managing induced
seismicity risks, and ensuring environmental compatibility.
Geothermal Energy in Global Energy Mix
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Baseload Reliability: Geothermal power provides stable electricity supply unlike solar and
wind energy, making it ideal for baseload power generation.
Long Operational Lifespan: Geothermal plants operate for decades with minimal
degradation, ensuring sustained energy production and reliability.
Applications Besides Power Generation
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District Heating: Directly heats residential and industrial areas, reducing heating costs and
enhancing energy efficiency.
Industrial Uses: Supports processes like drying, pasteurizing, and food processing,
improving operational efficiency in various industries.
Geothermal Heat Pump
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Efficient Heating and Cooling: Geothermal heat pumps (GHPs) utilize constant
underground temperatures for efficient space heating and cooling in residential and
commercial buildings.
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Types: Includes closed-loop systems (horizontal and vertical loops) for optimal heat
exchange efficiency and open-loop systems utilizing water from wells or natural bodies.
Conclusion
In conclusion, geothermal energy presents a sustainable and environmentally friendly solution to the global
energy crisis. By tapping into the Earth's natural heat, geothermal power plants generate electricity with
minimal greenhouse gas emissions, offering a continuous and reliable energy source. The three main types
of geothermal power plants—dry steam, flash steam, and binary cycle—each have unique applications that
make them suitable for various geothermal resources. While the technology involves significant initial
investment and is location-specific, the long-term benefits, such as low operational costs and stable energy
supply, make geothermal energy a valuable component of the renewable energy mix. Continued
advancements in drilling techniques and resource management, along with supportive policies and financial
incentives, are essential to overcoming the challenges and expanding the use of geothermal energy globally.
As countries strive to reduce carbon footprints and transition to renewable energy sources, geothermal
power holds significant promise for a sustainable energy future.
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