Geothermal Energy
Powering our future with the fire beneath our feet
Our challenge
Many deny the existence of renewable energy.
Addressing global challenges demands a comprehensive strategy, with clean energy at its core. While wind and solar have made significant strides, prompting widespread adoption of renewables, we must explore all viable avenues to maximize our planet's green energy capacity. As our population surges, optimizing every energy source becomes critical.
Geothermal energy, though not the primary solution to climate change, represents a valuable and underutilized resource. Its advancement is crucial in our shift towards clean energy and in achieving the United Nation's 2050 net-zero emissions target. By broadening our sustainable power options to incorporate geothermal power, we enhance our ability to combat climate change and ensure long-term planetary sustainability.
History
Hot Springs
Geothermal power was utilized by North American indigenous people around 10,000 years ago. they were drawn to hot springs for both spiritual and practical reasons, such as preventing vegetables from spoiling or freezing, warmth, bathing, cooking, medical purposes, and as locations for social gathering.
Hot springs were used as gathering sites for various people and offering opportunities for trade, diplomacy, and cultural exchange, and were even fought over in medieval wars.
Over 200 years ago, Romans built shrines at hot springs, resulting as evidence that they sought to communicate with gods. They utilized geothermal energy for practical applications such as providing heating for buildings.
Throughout the nineteenth century, spas developed around geothermal vents such as hot springs and geysers.
First Efforts:
In the village of Chaudes-Aigues in France, the first geothermal district heating was documented during the 14th century, and is still operating today.
1818 was the first successful effort to harness geothermal energy for industrial use in Tuscan region of Italy. French engineer François Jacques de Larderel discovered a new way to extract boric acid from hot springs to produce electricity.
United States first district heating system was built in Boise, ID in 1893. Due to the system being clean and economical, district heating is becoming increasingly popular.
First Geothermal Power Plant
Italian scientist Piero Ginori Conti achieved a breakthrough in 1904 by harnessing Earth's heat to operate a compact electricity generator, illuminating a handful of light bulbs.
The first geothermal power plant was a dry steam plant invented by Prince Piero Ginori Conti at the Larderello dry steam field in Tuscany, Italy. The original building was destroyed during WWII, but have been rebuilt and expanded, and is still producing today.
The Pacific Gas and Electric Company operated United States' first large scale geothermal power plant at The Geysers with capacity of 11 megawatts in 1960. Today, there are 23 power plants at the Geysers, with a combined capacity of 2043 MW.
The engagement of geothermal district heating in the U.S was spurred by the oil crisis of 1970s.
The 1980s marked a significant expansion of geothermal district heating networks across the United States. This decade also brought technological leaps in geothermal power generation, including successful implementations of both flash steam and binary cycle systems.
In the 1990s the geothermal heat pump market grew rapidly in the U.S and in Europe.
In 2005, 77 nations collectively achieved a thermal capacity installation of 28,268 MW, translating to an estimated yearly energy utilization of 75,943 GW.
In the 2000s, the total direct use of China, Iceland, U.S, and Turkey employed over 50% of the world wide total.
Earth's Role in Geothermal Energy
Approximately 4000 miles below the surface, lies Earth's core. This central region is believed to reach scorching temperatures between 2,760 and 6,090 degrees Celsius. Enveloping the core is the mantle, a 1800 miles thick layer composed of both solid rock and magma material.
The outermost layer of Earth, known as the crust, acts as an insulating blanket and is fragmented into sections called tectonic plates. These massive slabs, which make up continents and ocean floors, slowly shift and collide at a rate of about 20 millimeters annually through a process called plate tectonics.
This tectonic activity can lead to the crust becoming fractured, faulted, or thinned, allowing magma from deeper layers to ascend. While some of this molten rock reaches the surface to form volcanoes, the majority remains underground, contributing to the formation of expansive mountain ranges.
In regions with subterranean water sources, magma can infiltrate rock fissures and porous formations. As this water heats up, it circulates back to the surface, manifesting as hot springs, mud pots, and fumaroles – openings in the Earth's crust that release hot volcanic gases or vapors. These phenomena are indicators of deep geothermal reservoirs beneath the surface.
Where can Geothermal energy be found?
There are many methods for geologists to find geothermal reservoirs:
-Study aerial photographs and geological maps
-analyze chemistry of of local water sources and concentration of metals in the soil
-measuring variations in gravity and magnetic fields
The only accurate method is drilling an exploratory well to measure the temperature.
Most active geothermal zones (hot spots) are typically surrounded by major plate boundaries, where earthquakes and volcanoes are concentrated. The Ring of Fire is a horseshoe-shaped area in the Pacific Ocean basin known for intense tectonic and volcanic activity. This region is highly relevant to geothermal energy due to its unique geological characteristics. The high concentration of volcanoes in the Ring of Fire indicates that heat is close to the Earth's surface. These geological conditions make the region exceptionally rich in geothermal energy resources. Many countries along the Ring of Fire harness this energy for power generation. The abundance of geothermal resources in this area has driven significant advancements in geothermal technology.
Main methods of Geothermal electricity conversion
Dry Steam Plants
Dry steam plants extracts steam directly from the reservoir at a high pressure to power steam turbines, where the condensed steam is then discharged into the atmosphere or back into the reservoir.
Flash Steam Plants
Hot, pressurized geothermal fluids are brought to the surface and rapidly depressurized, causing partial vaporization or "flashing." The resulting steam drives turbines for electricity generation. Remaining liquid can undergo further flashing stages to extract additional steam, optimizing energy production from the geothermal resource.
Binary-Cycle Power Plants
Similar to dry steam and flash steam plants, binary-cycle geothermal plants use geothermal fluid to heat a separate working fluid, which then powers a turbine. This closed-loop system allows full re-injection of geothermal fluid and can operate at lower temperatures than traditional plants. As a result, binary systems expand geothermal energy's viability to more locations globally.
Parts of the Geothermal Power Plant
Production Well
Thermal fluid at elevated temperatures is extracted from deep underground via an extraction borehole, often referred to as the production well, which may extend thousands of meters below the Earth's surface.
Heat Exchanger
A thermal transfer device, known as a heat exchanger, utilizes the elevated temperature of the geothermal fluid to transform a low-boiling-point substance, such as isobutane, from a liquid to a gaseous state.
Turbines
The isobutane, now in a highly pressurized gaseous form, propels the rotary components of a turbine generator, converting it into electricity.
Cooling tower
The cooling tower helps remove excess heat from the power generation process. It cools and condenses the working fluid after it has passed through the turbine, allowing it to be recycled back into the system. This process ensures proper temperature differentials and help to conserve water resources.
Injection well
The injection well serves as a conduit to return the cooled fluid back into the subterranean heat reservoir, completing the geothermal cycle and helping to maintain the system's long-term sustainability.
Geothermal Loop
Geothermal loops are path of pipes that travels below the ground, deep enough to reach the zone that has constant temperature. The loop contains liquid that consists of water or a mixture of water and antifreeze. Depending on the building, the structure of the pipes will differ.
Horizontal Pipe: most common for residential, where the land has more room for pipes, therefore being cheaper due to less digging.
Vertical Pipe: Most common for large businesses and commercial buildings, which requires more digging deeper underground to avoid affecting landscape or certain soil disturbances.
These loops can also be installed in suitable bodies of water that must meet specific criteria before installing the geothermal loop system.
Open-loop vs. Closed-loop System
Closed-Loop system: This system continuously circulates antifreeze solution though a closed-loop submerged plastic pipes. The loop is filled just once with a moderate amount of solution, used over and over again.
Open-loop system: An open-loop system pipe directly draws fresh undergroundwater from a proximate aquifer and channeled into an interior geothermal heat pump. Once the water is circulated through the home's system, it's returned to the environment in a discharge well. The used water will them be released into a nearby pond or an authorized drainage channel.
Distribution system
This system transfers hot or cold air throughout the building. There are two different options:
forced air system: This system relies on a network of ducts and and air handler to distribute temperature-controlled air throughout the building. This setup is essential for circulating heated or cooled air throughout the spaces of the building or home.
Water-to-water system: This system requires pipes to run through walls or the floor to transfer heat. The pipes carry hot or cool liquid that comes from the geothermal loop system that connects to the main geothermal heat pump.
Geothermal Heat Pumps
A residential geothermal system harnesses the Earth's steady underground temperature to regulate indoor climate. At its core is a heat pump, usually placed in a home's lower level. This pump manages a closed loop of pipes buried deep in the ground, typically around 300 feet down.
The fluid circulating through the buried pipes absorbs this warmth and transports it to the heat pump. From there, the captured heat is distributed throughout the building.
When temperatures rise, the system shifts gears. It draws excess heat from inside the home, transfers it to the circulating fluid, and then releases it into the cooler earth below.
This dual-purpose system leverages the planet's natural thermal stability to provide both heating and cooling. By tapping into this renewable energy source, geothermal systems offer an efficient method of temperature control that works in harmony with the Earth's innate thermal characteristics throughout the year.
Benefits:
Energy Production and Potential
The average of 25 billion barrels of hot water produced in US oil and gas wells each year could be harnessed to produce up to 3 GW of clean, reliable baseload of energy. Conventional geothermal sources in 13 US states have a potential capacity of 38,000 MW, which could produce 308 million MW of electricity annually. Hot dry rock resources could provide another 4 million MW of capacity, equivalent to more than all of today's U.S. electricity needs. Geothermal power plants could potentially provide between 0.0035 and 2 terawatts of power globally.
Economic Benefits
The levelized cost of energy (LCOE) for new geothermal plants is projected to be less than 5 cents per kilowatt hour, compared to more than 6 cents for new natural gas plants and more than 9 cents for new conventional coal. Annual energy savings for homeowners can be reduced by 30-70% in heating mode and 20-50% in cooling mode with geothermal heat pumps. Geothermal systems have a long equipment life, lasting 20% longer than conventional systems, and have the lowest life cycle cost.
Environmental Benefits
Geothermal energy reduces greenhouse gas emissions and environmental damage associated with non-renewable extraction. It eliminates the combustion of fossil fuels on-site and dramatically lowers the need to generate power. Geothermal energy is a renewable resource that will last until the Earth is destroyed by the sun in around 5 billion years.
Operational Advantages
Binary plants can ramp production up and down multiple times each day, from 100% of nominal power down to a minimum of 10%. Geothermal energy is a continuous, baseload power source, unlike intermittent renewables like wind or solar. The ground's resistance to seasonal heat changes allows it to act as a heat sink/source for geothermal heat pumps just two meters below the surface. Energy output from geothermal plants is highly predictable and easy to calculate. No fuel is required for ongoing operation.
Industry Integration
Using geothermal fluids from existing oil and gas wells for power production can extend the economic life of these wells. This integration can deliver near-term energy savings and reduce greenhouse gas emissions. It could increase profitability and extend the economic life of existing oil and gas field infrastructure.
Disadvantages:
Environmental Concerns
Open systems like the Geysers emit some air pollutants, including hydrogen sulfide, trace amounts of arsenic, and minerals. Salt buildup in pipes can pose an environmental problem, though some systems now re-inject salt back into a different well. Open Loop systems waste steam and gases into the atmosphere, resulting in greater environmental impacts than closed loop systems. Air and water pollution are two leading environmental issues associated with geothermal energy technologies. Most geothermal plants require large amounts of water for cooling and heating, which can raise conflicts with other water users or uses, such as fish spawning and rearing in water-scarce areas.
Geological Risks
There's a possibility of induced seismic activity from hot dry rock drilling and development, similar to hydraulic fracturing. Risks of triggering earthquakes due to alterations in Earth's structure as a result of digging, particularly when forcing water into Earth's crust to open up fissures. Land subsidence is a concern associated with geothermal energy extraction.
Greenhouse Gas
EmissionsAlthough geothermal energy doesn't emit greenhouse gases during operation, the digging process can release gases stored under Earth's surface into the atmosphere. These gases include sulfur dioxide and carbon dioxide, though emissions are still 99% less than fossil fuel power plants.
Resource Management Challenges
To maintain sustainability, fluid needs to be pumped back into the underground faster than it is depleted, requiring proper management. Safe disposal of hazardous waste is an additional concern.
Geographical Limitations
Geothermal plants are restricted in location, needing to be situated where the energy is accessible, typically near the Earth's surface.
Current Applications of Geothermal Energy
Government Support and Funding
The American Recovery and Reinvestment Act of 2009 allocated $400 million of new funding to the DOE's Geothermal Technologies Program.
$90 million funded 7 demonstration projects to prove the feasibility of Enhanced Geothermal Systems (EGS) technology.
$50 million funded 17 demonstration projects for new technologies, including co-production with oil and gas and low-temperature geothermal.
Remaining funds were directed towards exploration technologies, expanding deployment of geothermal pumps, and other initiatives.
Global Geothermal Electricity Production (2022)
24 countries, including the US, generated about 92 billion kWh of electricity from geothermal energy. Indonesia was the top geothermal electricity producer, generating 17 billion kWh (5% of Indonesia's total electricity generation). Kenya ranked 7th highest, producing 5 billion kWh (45% of its annual electricity generation).
U.S. Geothermal Energy Status (2023)
The U.S. had geothermal plants operating in seven states. These plants produced about 17 billion kilowatt-hours of electricity. This accounted for approximately 0.4% of total U.S. electricity generation.
State-Level Initiatives (2023)
Governor Jared Polis of Colorado launched "The Heat Beneath Our Feet" as the 2023 Western Governors' Association (WGA) Chair initiative. This initiative aims to: a) Examine opportunities for increasing geothermal energy deployment in western states. b) Identify barriers to geothermal energy adoption. c) Focus on both electricity generation and heating/cooling systems. The initiative recognizes that western states hold the majority of high-yield geothermal energy capacity in the US.
This initiative highlights the growing interest in geothermal energy at the state level, particularly in regions with high geothermal potential. It also demonstrates a push for comprehensive examination of both the opportunities and challenges in expanding geothermal energy use.
Global Geothermal Capacity37 countries are currently utilizing geothermal power. There are 577 geothermal power units globally. The current operating capacity is 13.9 GW. There is an additional 12.8 GW of prospective capacity.
U.S. Geothermal Heat Exchange SystemsApproximately 3.5 million homes and buildings in the U.S. currently use geothermal heat exchange systems.
This information provides a broader context for geothermal energy use worldwide and highlights the significant adoption of geothermal heat exchange systems in the United States. The global figures demonstrate the current scale of geothermal power generation and the potential for future growth.
Conclusion
Geothermal energy represents a groundbreaking frontier in renewable power, poised to revolutionize our approach to sustainable energy generation. Despite potential challenges and considerations, the immense advantages offered by this innovative technology cannot be overlooked or understated. Traditional fossil fuels like oil and coal, and even other renewable sources like wind and solar, are increasingly proving inadequate to meet our long-term energy needs in an environmentally conscious manner. It is imperative that the wider public becomes aware of and educated about the transformative potential of geothermal energy systems. To this end, The Energy Outlook will serve as a vital platform, regularly discussing the latest developments, breakthroughs, and compelling narratives surrounding this underutilized energy source. By disseminating this crucial information, we aim to foster greater understanding and support for a technology that could play a pivotal role in constructing a more sustainable and prosperous global future.
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