MUSE – Differences between deep and shallow geothermal energy (Part 1)

MUSE – Differences between deep and shallow geothermal energy (Part 1)

The term geothermal energy covers a wide field of applications at different depth and temperature levels or based on different technologies to extract geothermal heat. Although all kind of geothermal energy originates in the Earth’s interior, the technologies clearly differ in their range of application and concepts. In this blog we will have a look on the terms “shallow“ and “deep geothermal” and try to explain how these systems differ and what they have in common.

What do “shallow” and “deep” geothermal energy have in common?

One has to bear in mind that the terrestrial heat flux alone, ranging between <50 mW/m² and 200 mW/m², is not strong enough to supply geothermal applications. Therefore, using geothermal energy in all of its different kinds means harvesting the heat stored in porous, water filled rocks of the subsurface, which is available around the year at the same capacity. Using it sustainable requires appropriate planning and resource management!

Both systems, “shallow” and “deep geothermal” allow for heating, cooling and underground heat storage and, apart from petrothermal energy (e.g. Hot Dry Rock), they refer to the same technological principles for heat recovery from the subsurface.

Ok, and how do “shallow” and “deep” geothermal differ?

First, let’s take a look at the terminology: The terms “shallow” and “deep” refer to the depth of the heat absorber, which can harvest heat either from subsurface water with an open loop system or from the solid ground with a closed loop heat exchanger. There is no uniform definition for “shallow” and “deep”. In most countries, the depth separation is regulated by the Mining Act requiring a permit for drillings (mostly between 100 and 400 meters below surface). The Mining Act influences the drilling market and the depth range. For depth levels up to around 150 meters, a large market exists offering low drilling costs, which makes shallow geothermal energy affordable to private households as well. In contrast, deep geothermal energy requires long term planning and high investments with regard to drilling costs.

Study and practice the list of keywords related to the text. Here is a list of 20 key words from the text along with their phonetic transcriptions:

·      

·      Geothermal - /dʒiːəʊˈθɜːrməl/

·      Applications - /ˌæplɪˈkeɪʃənz/

·      Temperature - /ˈtɛmpərətjʊə/

·      Technologies - /tɛkˈnɒlədʒiz/

·      Extract - /ɪkˈstrækt/

·      Interior - /ɪnˈtɪəriər/

·      Differ - /ˈdɪfər/

·      Common - /ˈkɒmən/

·      Terrestrial - /təˈrɛstrɪəl/

·      Flux - /flʌks/

·      Subsurface - /ˈsʌbsɜːrfɪs/

·      Sustainable - /səˈsteɪnəbl/

·      Planning - /ˈplænɪŋ/

·      Resource - /rɪˈsɔːrs/

·      Management - /ˈmænɪdʒmənt/

·      Petrothermal - /ˌpɛtrəˈθɜːrməl/

·      Principles - /ˈprɪnsəpəlz/

·      Recovery - /rɪˈkʌvəri/

·      Terminology - /ˌtɜːmɪˈnɒlədʒi/

·      Drillings - /ˈdrɪlɪŋz/

This short, 60-second animation explains exactly how shallow geothermal systems (ground-source heat pumps) work for private households:

How this relates to your keywords and text:

• Shallow Systems: The video focuses on the subsurface just below the frost line (the "shallow" depth mentioned in your text).

• Technologies & Principles: It demonstrates the closed-loop heat exchanger principle mentioned in your text, showing how pipes in the solid ground harvest heat.

• Applications: It clearly illustrates how the system provides both heating in the winter and cooling in the summer by moving heat between the house and the ground.

• Sustainability: It highlights how the system uses the Earth as a constant-temperature resource, making it more sustainable than traditional fossil fuel systems.

This video perfectly complements the text's explanation of why these systems are increasingly affordable and popular for private households at depths up to 150 meters.

Here are some open-ended discussion questions based on the text:

1

1. What is geothermal energy, and how does it differ in its applications at various depth and temperature levels?
2. Why is it important to understand the differences between "shallow" and "deep" geothermal energy in terms of their range of application and concepts?
3. Explain the role of terrestrial heat flux in geothermal applications and why it alone is not sufficient.
4. Discuss the significance of harvesting heat from porous, water-filled rocks in the subsurface for sustainable use of geothermal energy.
5. How do both "shallow" and "deep geothermal" systems contribute to heating, cooling, and underground heat storage?
6. Aside from petrothermal energy, like Hot Dry Rock, what other technological principles are mentioned for heat recovery from the subsurface?
7. What challenges or considerations might arise when attempting to define "shallow" and "deep" geothermal in different countries?
8. In your opinion, why does shallow geothermal energy become more affordable to private households, especially in the depth range up to 150 meters?
9. Discuss the impact of the Mining Act on the depth separation between "shallow" and "deep" geothermal and its influence on the drilling market.
10. Considering the long-term planning and high investments required for deep geothermal energy, what factors should be taken into account when deciding to invest in such projects?

🎤 The Great Geothermal Grudge Match

Moderator: "Welcome, students! Today we settle the score. Is the future of energy right under our toes, or is it a journey to the center of the Earth? Let’s meet our teams."

🟢 Round 1: Initial Statements

The Shallow Soil Squad (Team Shallow): "Listen, while our opponents are spending billions of dollars trying to tickle the Earth’s mantle, we’re already at work! Shallow geothermal is the 'People’s Energy.' We’re talking about 150 meters of pure, affordable efficiency. We don't need a Mining Act permit just to say hello to a rock; we just need a backyard and a dream. We harvest the subsurface like a thermal garden. It’s sustainable, it’s cheap, and frankly, we don’t need a tuxedo to afford the drilling costs!"

The Deep Drill Dynamos (Team Deep): "How cute. Team Shallow is playing in the sandbox while we’re solving the world’s energy crisis! You call 15 degrees 'energy'? That’s not energy; that’s a lukewarm gazpacho! We go deep—down where the real heat is. We’re talking Petrothermal power, baby! We don't just heat a single-family home; we heat entire cities. If you want to change the world, you have to go deep or go home. Yes, it’s expensive, but since when was saving the planet supposed to be at 'dollar store' prices?"

🔴 Round 2: The Rebuttal (The "Heat" is On)

Team Shallow Rebuttal Question: "To Team Deep: You mentioned 'planning.' Is that code for 'waiting 20 years for a permit while the Mining Act lawyers take all your money'? How can you be the future when a private household can’t even afford your entrance fee?"

Team Deep Rebuttal Question: "To Team Shallow: You claim to be 'sustainable,' but you rely on terrestrial heat flux that the text says is <200 mW/m². You’re basically just stealing leftovers! What happens when you suck all the heat out of your little 150-meter hole and turn your backyard into an ice cube?"

🟡 Round 3: The "Terminology" Takedown

Team Shallow: "We don't 'suck the heat out,' we manage it! We use the subsurface for cooling in the summer and heating in the winter. It’s a loop, Team Deep! A cycle! While you’re down there risking a volcanic eruption just to boil a kettle, we’re using elegant Heat Recovery principles to keep things comfy and climate-friendly."

Team Deep: "Elegant? You’re using a heat pump! That’s just a refrigerator in reverse. We use the raw, unadulterated interior heat of the Earth. We are the masters of the flux! We don't need 'ambient' temperatures; we provide the heavy-duty power that industry demands. You’re a band-aid; we’re the cure!"

🏁 Final Considerations: The Cooling Off Period

Moderator: "Alright, settle down before we trigger a seismic event! Let’s have your closing thoughts."

Team Shallow: "In conclusion: Shallow is accessible, it’s here now, and it’s for everyone. We are the democratic choice for a green future. Don't go deep into debt—go shallow into the ground!"

Team Deep: "In conclusion: If you want to replace coal and gas, you need the big guns. Deep geothermal is the only way to get the temperatures needed for a true energy revolution. Don't be afraid of the dark—the treasure is at the bottom!"

👨‍🏫 Teacher's Summary for the Class

"Both teams are right! Shallow is perfect for decentralized heating/cooling and private homes because of lower costs and established drilling markets. Deep is essential for large-scale energy production and district heating, despite the high risks and complex 'Terminology' of the Mining Act. Whether you’re an open-loop fan or a petrothermal pioneer, the subsurface is our best battery!"

First and Second Conditional

https://drive.google.com/file/d/1zQFmqylCWET63Ute5yaqDYR1MgA_ikQj/view?usp=sharing

Learning review: Kahoot

https://create.kahoot.it/share/muse-differences-between-deep-and-shallow-geothermal-energy/7f0328e7-5405-46b8-a3cc-f8bdbccf8298