Geothermal Concepts

[Alex2448]

Description of the issue

here are several technologies which use different depth level of geothermal heat. The deeper you drill, the hotter it is and you can get more heat but there are also higher risks and costs. In general, we distinguish between 2 layers of depth:

• Near-surface geothermal depth (up to 500m)
• Deep geothermal depth (1500m - 4500m)

Downhole heat exchanger and geothermal collector and geothermal wells are used in near-surface geothermal depth. For hydrothermal geometrie, drillings are carried out in deep geothermal depth and water (with high temperatur) from high depths is transported to the surface. This is quite similar to geothermal wells except that the wells are in near-surface geothermal depth. So to distinguish these two kinds of technology, introducing different depth level is conveniant.

The difference between petrothermal geothermal (like downhole heat exchanger and geothermal collector) and hydrothermal geothermal is that hydrothermal geothermal get the thermal energy from water which is already in the crust and petrothermal geothermal, water is pressed in the drills. So distinguishing between different media is also conveniant to describe the technologies.

This may need some discussion on how to introduce these concepts and terminologies.

In oeo dev 42, we discussed that Near-surface geothermal depth (up to 500m) and Deep geothermal depth (1500m - 4500m) of geothermal energy can be similar described like sector division. So the proposal in this meeting was: Creating a new subclasss of sector division: 'crust depth division'. The problem is that I cannot find any suitable destinction (besides hard numbers in meter or temperature in °C) of the crust, since we still drill in the crust and not in the mantle.

The whole discussion is copied from Issue#1254.

Ideas of solution

• Introduce geothermal well system which has as parent class geothermal heat plant:

  • Def:
  • A geothermal well system is a geothermal heat plant that has geothermal heat units as parts.
  • Axiom:
  • uses some water

• Additionally, there are other components of geothermal heat plants which have as parent class heat exchanger:

• • Def:
  • A subsurface collector is a heat exchanger that transfers ambient thermal energy. It consists of plastic pipes laid horizontally.
  • Axiom:
  • 'has energy input' some 'ambient thermal energy'
• • Def:
  • A downhole heat exchanger is a heat exchanger that transfers thermal energy. It consists of plastic pipes installed vertically or inclined in a borehole.
  • Axiom:
  • 'has energy input' some 'ambient thermal energy'

Workflow checklist

• [x] I discussed the issue with someone else than me before working on a solution
• [x] I already read the latest version of the workflow for this repository
• [x] The goal of this ontology is clear to me

I am aware that

• [x] every entry in the ontology should have a definition
• [x] classes should arise from concepts rather than from words

[l-emele]

This issue is now stale for half a year. I don't know whether these classes are still needed. Anyway, here my thoughts:

A geothermal well system is a geothermal heat plant that has geothermal heat units as parts.

This definition makes no sense to me as a geothermal heat plant is already defined as: A geothermal heat plant is a heat plant that has geothermal heat units as parts.

Regarding the other two proposals I suggest a small modification:

• A subsurface collector is a heat exchanger that transfers ambient thermal energy to a working fluid. It consists of plastic pipes laid horizontally.
• A downhole heat exchanger is a heat exchanger that transfers thermal energy to a working fluid. It consists of plastic pipes installed vertically or inclined in a borehole.

If we also want to add working fluid I propose:

• A working fluid is a fluid that is used to transfer thermal energy.

[l-emele]

@stap-m : Could you please provide feedback on my last comment?

[stap-m]

Sounds reasonable. Can we specify the kind of thermal energy for downhole heat exchanger, too? Geothermal, ambiental, both?

[l-emele]

Sounds reasonable. Can we specify the kind of thermal energy for downhole heat exchanger, too? Geothermal, ambiental, both?

I think both. So I refine my proposal:

• A downhole heat exchanger is a heat exchanger that transfers ~thermal energy~ ambient thermal energy or geothermal energy to a working fluid. It consists of plastic pipes installed vertically or inclined in a borehole.

[stap-m]

Ready for implementation, I guess.

[l-emele]

Okay, I'll implement.