In-Depth Notes on Geothermal Energy

Geothermal energy is less recognized compared to other renewable energies (such as solar, wind, or hydro) due to several factors:
- Location: Not evenly distributed; often found in specific geological areas.
- Cost: Higher initial investment costs.
- Complexity: More complex extraction and generation compared to other renewables.

Predictability: Similar to fossil fuels, geothermal energy can be controlled and supplied predictably, offering stability in energy production.
Heat Extraction:
- If drilling goes too deep, it risks hitting unextractable metal resources.
- The extraction method resembles fossil fuel drilling, indicating geological challenges.

Direct Use and District Heating:
- Uses hot water from underground springs or reservoirs directly for heating applications.
- Common in residential heating or district heating systems.
Electricity Generation:
- Power plants require water or steam at high temperatures (300-700°F).
- Ideal geothermal reservoirs are located within 6000 ft of the Earth’s surface.
Geothermal Heat Pumps:
- Utilize stable shallow ground temperatures for heating and cooling buildings efficiently.
- Typically draw water from up to 1000 ft below the surface.

Dry Steam Power Plants:
- Use steam directly from underground reservoirs to drive turbines directly.
- Resulted in minimal emissions, primarily excess steam.
- First type of geothermal power plant developed in Italy (1904).
Flash Steam Power Plants:
- Utilize high-pressure hot water from geothermal reservoirs that flashes to steam under lower pressure.
- Can operate as double or triple flash systems to maximize output.
Binary Cycle Power Plants:
- Use lower-temperature geothermal fluids which transfer heat to a secondary fluid with a lower boiling point.
- Operate in a closed-loop system, producing little to no emissions.

Most geothermal resources are near tectonic plate boundaries, especially along the Pacific Ring of Fire, where volcanic activity is prevalent.
In the U.S., geothermal power is concentrated in western states and Hawaii, with California leading in geothermal electricity generation.

Geothermal capacity statistics in 2020:
- U.S.: 3,714 MW
- Indonesia: 2,133 MW
- Philippines: 1,918 MW
- Turkey: 1,526 MW

EGS refers to geothermal resources that lack sufficient natural water and require the injection of water into hot, dry rock.
The aim is to create a stable and efficient heat exchange process to produce steam for electricity generation.
EGS exhibits potential for wider development across various regions globally.

Incident at Pohang, South Korea (2017): A significant earthquake (5.4 magnitude) was linked to an EGS project that injected fluid at high pressure into rock, causing seismic events.
- Highlighted the risk of induced seismicity in EGS projects.

Different from EGS, AGS uses closed-loop systems withdrawing heat from deep geological formations without introducing fluids into the Earth.
Technologies leveraged from the oil and gas sector, such as advanced drilling techniques, enhance the efficiency and minimize risks associated with geothermal energy extraction.

Quaise Energy is developing innovative drilling technologies allowing access to depths of 12 miles, hunting for extreme heat sources for power generation.
The main goal is to transition existing fossil fuel power plants to geothermal by using advanced drilling methods.

Geothermal energy represents a unique and sustainable resource with significant potential for both direct heating and electricity generation.
As technology evolves and societal awareness increases, the opportunities for geothermal energy may expand, addressing both energy needs and climate change concerns effectively.