The Role of Geothermal Energy, a renewable energy source using Earth's heat, in our future

Introduction to Geothermal Energy

Geothermal energy, a renewable energy source harnessing the Earth's natural heat, is becoming an increasingly vital part of the global energy landscape. 

This form of energy is clean, sustainable, and holds tremendous potential in powering the needs of our evolving societies and the fight against climate change. There is so much capacity available, it can even support baseload energy which is the constant, minimum amount of electricity required to meet continuous demand within an electrical grid. 

In this post, we will explore how geothermal energy works, dive into the different applications, where it's found, and its future potential in the energy market.

How Geothermal Energy Works

Geothermal heat originates from the Earth's spinning core, where temperatures reach over 5000°C, and the heat radiates outwards towards the crust and eventually space.  

This immense heat is conducted to the Earth's crust, heating rocks and underground reservoirs of water. 

Applications of geothermal energy range from direct use like spa bathing and aquaculture heating to electricity generation to industrial processes and district heating/cooling with heat pumps.

Types of Geothermal Energy Application

Direct Use of Geothermal Energy

Direct application of geothermal heat is used without the need for complex conversion to electricity and is most suited in regions with naturally occurring hot springs and geothermal reservoirs. 

The Western United States, including states like California, Nevada, and Idaho, offer prime locations for these applications. 

The natural geological features in these regions, such as where the Earth has thin crust and tectonic movements, allow more affordable access to the heat readily available 24 hours a day. 

Examples include agricultural drying, aquaculture pond heating, and therapeutic bathing.

Electricity Generation with Geothermal Energy

In the western half of the United States, where tectonic activity and volcanic regions are more prevalent, high-temperature geothermal resources are well-suited for electricity generation and contribute to sustainable energy goals. 

States like California, Nevada, and Oregon have significant potential for geothermal power plants that harness the high-temperature resources called hydrothermal fluids, which are hot water and steam mixtures found beneath the Earth's surface. 

In a traditional electricity generation facility (power plant), fossil fuels are burned to produce heat, which turns water to steam. Steam is used to spin turbines, and the turbines generate electricity by moving magnetic fields. The elimination of fossil fuels such as coal, oil, and natural gas from the production process leads to less emissions and higher efficiency. Geothermal electricity production is three to four times more efficient and emits approximately 98% less acid rain-causing sulfur and carbon dioxide compounds.

In the U.S. alone, it is estimated that 31% of climate change effects can be attributed to electricity (EIA, 2023). The higher geothermal power plant efficiencies and lower emissions are massive contributors to a more sustainable future. 

Various geothermal power plants convert hydrothermal fluids to electricity:

• Flash Steam Plants: Use water at temperatures greater than 182°C.

• Binary Cycle Power Plants: Operate on water at lower temperatures of about 107-182°C.

• Dry Steam Plants: Utilize steam from fractures in the ground.

Geothermal Heat Pumps

Geothermal heat pumps (GHPs) play a core role in modern HVAC systems in buildings that control heating in the winter and cooling in the summer. They can utilize the relatively stable temperatures found a few feet below the Earth's surface to either absorb heat or provide heat.

This technology is very versatile and can be applied almost anywhere, including the eastern half of the U.S., where the geothermal gradient may not be as steep as in more tectonically active areas. Transitioning conventional HVAC systems to geothermal heat pumps poses one of the largest ways geothermal resources can reduce emissions because HVAC systems are responsible for roughly 6% of global emissions (Mills, 2023).

• Heating Mode: GHPs extract heat from the ground, providing warm air in winter.

• Cooling Mode: During summer, GHPs take heat from the building and transfer it to the ground.

• Energy Efficiency: GHPs achieve efficiencies 25% to 50% greater than traditional HVAC systems.

• Integration with Existing Systems: GHPs can be retrofitted into existing HVAC systems.

Types of Geothermal Heat Pumps include:

• Closed Loop Systems: Circulates a heat exchange fluid through a continuous loop of buried pipes. This fluid absorbs heat from the ground for heating or dissipates heat into the ground for cooling, without interacting directly with groundwater.

• Open Loop Systems: Use groundwater as a direct energy source, circulating the water through the system for heating or cooling, then returning it to the ground or a body of water. It is efficient, but requires abundant water.

GHPs are used in residential buildings, commercial buildings, government and public infrastructure, and hybrid systems that combine with other renewable energy sources like solar, wind, biomass, and hydroelectric. These combinations enable more consistent energy supply and can optimize the overall system performance, especially in locations where one energy source might be seasonal or intermittent. Combining geothermal with other renewables creates a more resilient and versatile energy solution.

Market Adoption Challenges with
Geothermal Heat Pumps

Despite their benefits, GHPs face several barriers to wider adoption:

• High Upfront Costs: The initial installation can be expensive.

• Lack of Awareness: Many potential users are not aware of geothermal technology.

• Geographical Limitations: Efficiency can vary based on soil composition and temperature.

• Regulatory Hurdles: Some regions have regulations and permitting requirements that create barriers.

• Skilled Labor Shortage: A lack of trained technicians can slow down adoption rates.

Where Geothermal Energy
Generation is Found Globally 

Geothermal energy for electricity generations has the most potential in regions with significant volcanic or tectonic activity. Countries like Iceland, El Salvador, New Zealand, Kenya and the Philippines, which generate a substantial portion of their energy from geothermal sources, are leaders in this field.

Other areas with high potential include parts of Italy, and parts of East Africa's Rift Valley, Indonesia, Central and South America along the pacific borders, Japan, and Turkey (Geothermal Energy, n.d.).

These regions have abundant geothermal resources that can be harnessed for electricity generation, direct heating applications, and other uses, contributing to global sustainability and energy independence.

Potential in the Renewable Energy Market

Geothermal energy offers a highly reliable and sustainable energy source:

• Low Environmental Impact: Minimal emissions and land use.

• High Availability: Available 24/7, unlike solar or wind.

• Job Creation: Can boost local economies.

• Integration Capabilities: Can be combined with other renewable energy sources.

Conclusion

The role of geothermal energy in shaping a sustainable future is clear and compelling. Its diverse applications range from direct usage to complex electricity generation, including the exciting and energy-efficient solution of geothermal heat pumps in modern HVAC systems.

Addressing the barriers to wider adoption requires collaboration between governments, industry, and educational institutions to promote awareness, reduce costs, and simplify regulations. Continuous innovation, international cooperation, and supportive policies can further unlock geothermal energy's broader global adoption potential.

Whether in heating our homes, powering our industries, or integrating into our buildings' infrastructure, the growth of geothermal energy represents a valuable asset in our global energy portfolio and can play a vital role in reducing reliance on fossil fuels, enhancing energy security, and contributing to climate change mitigation efforts. By harnessing the immense thermal energy within our own planet, we are stepping towards a future that not only preserves our environment but ensures a steady and reliable energy supply.

The continued exploration and innovation in geothermal technologies are key to unlocking its full potential and contributing to a cleaner, more sustainable world.

Geothermal Energy in the Wild

Beautiful, blazing hot geothermal hot springs are one of the natural wonders of the earth. Be careful when at a unmonitored geothermal pool site, the mineral-dense water can change the color of your bathing suit and potentially burn your skin. Proceed with caution, and enjoy the many health benefits of hot spring baths. 

Sources / Additional Reading

Frequently Asked Questions (FAQs) - U.S. Energy Information Administration (EIA). (2023, August 15). Frequently Asked Questions (FAQs) - U.S. Energy Information Administration (EIA). https://www.eia.gov/tools/faqs/faq.php

Geothermal energy. (n.d.). Geothermal Energy. https://www.irena.org/Energy-Transition/Technology/Geothermal-energy#:~:text=As%20a%20renewable%20resource%2C%20geothermal,with%20distinct%20levels%20of%20maturity.

Mills, R. (2023, March 29). Clean Energy 101: Geothermal Heat Pumps - RMI. RMI. https://rmi.org/clean-energy-101-geothermal-heat-pumps/