Ontology: Reformulate Ambient Heat

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

Description of the issue

This arose from #393 and subsequent discussions in OEO developer meetings 15 and 16.

The class ambient heat needs renaming (its an energy, not a heat) and a proper definition, and additional classes along the lines set out at the energy subclasses meeting:

• A: primary energy process
• B: transformation process
• C: primary energy
• D: primary energy carrier
• E: relations

Ideas of solution

Discussion so far culminated with

• A (primary energy process):
  _missing_
• B (transformation process):

Ambient thermal energy transfer is a heat transfer from the ambient air to a transportable material entity.

• C (primary energy):
  Ambient thermal energy is thermal energy that is naturally around us in its diffuse and extended form and emanates from a diversity of heat sources, including earth, water, or air.
• D (primary energy carrier):
  earth/rock, water, air
• E (relations):
  _missing_

At OEO developer meeting 15 the question of the distinction between _ambient thermal energy_ and _geothermal energy_ (#727) was brought up, with no conclusion.
At OEO developer meeting 16, the further question of the need and possible structure of a super-class encompassing both _ambient thermal energy_ and _geothermal energy_ (#727) was brought up, with no conclusion.

Workflow checklist

• [ ] 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

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

Two (counting clicking further once) existing definitions of _ambient thermal energy_ where linked at OEO developer meeting 16:

One from EUROSTAT: Ambient heat

Heat energy at a useful temperature level, extracted (captured) by means of heat pumps that need electricity or other auxiliary energy to function. This heat energy can be stored in the ambient air, beneath the surface of solid earth or in surface water. Values shall be reported using the same methodology as the one used for reporting heat energy captured by heat pumps under Directive 2009/28/EC, but all heat pumps should be included regardless of their performance level.

For me it reads like heat _after_ the heat pump. "At a useful temperature level" is not ambient temperature, and "extracted (captured) by means of heat pumps" is a past participle, so the activity is finished. So that would not be primary energy, but secondary energy.

The other from Umweltbundesamt: Umgebungswärme (by way of ibid. Geothermie)

Ambient heat includes both environmental heat and near-surface geothermal heat. Environmental heat includes the heat extracted from air layers near the ground ("aerothermal environmental heat") and from surface waters ("hydrothermal environmental heat") and made technically usable. Near-surface geothermal energy refers to the heat stored in the ground near the surface up to a depth of 400 metres ("geothermal ambient heat"); this also includes the heat in groundwater. Both energy sources are too cold to be used directly for heating buildings, which is why heat pumps are used.

The salient point here to me is that both definitions boil down to

_Ambient thermal energy is captured by heat pumps._

The limitation to depth (400 m) is the same as a limitation on temperature (higher depth → higher temperature) which in turn implies the use of heat pumps. Also it is certainly region-specific. Geologically more active regions (Iceland) will reach "useful temperature levels" that don't require heat pumps at shallower depths than Germany.

So I propose to distinguish between _geothermal energy_ and _ambient heat energy_ (from the ground) based on either the temperature level (probably not know to energy system models) or the use of heat pumps (probably known to energy system models, as that entails performance and cost parameters).

[stap-m]

Combining both sources:
_Ambient thermal energy is thermal energy that is naturally...
...stored in the ambient air, beneath the surface of solid earth or in surface water [EUROSTAT]. It is captured by heat pumps [UBA]._

Near-surface geothermal energy refers to the heat stored in the ground near the surface up to a depth of 400 metres ("geothermal ambient heat");[UBA]

Task: find a boundary between geothermal and ambient thermal energy as well as geothermal heat transfer and ambient thermal energy transfer. [OEO dev 15]

Referring to [UBA], ambient heat and geothermal (ambient) heat are not disjoint! Thus, maybe it's not nesessary to find/define a hard boundary, where there is none.

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

Referring to [UBA], ambient heat and geothermal (ambient) heat are not disjoint! Thus, maybe it's not nesessary to find/define a hard boundary, where there is none.

I concur. But there was at least no unanimity on this question at OEO developer meeting 16.
From my point of view, ontology users (energy system modellers) will know whether they modelled geothermal or ambient thermal energy, and annotate their models and data accordingly. The definitions of the ontology will not be used to figure out what modellers did.

_Ambient thermal energy is thermal energy that is naturally...
...stored in the ambient air, beneath the surface of solid earth or in surface water [EUROSTAT]. It is captured by heat pumps [UBA]._

Why "naturally"? How does one identify if the thermal energy in some body is of natural or technical origin?

[stap-m]

"naturally" stems from the original def developed in the meeting, see header of this issue. But I don't mind deleting it.

[l-emele]

The word "naturally" _might_ be relevant when distinguishing ambient heat from sub-surface thermal energy storages which are used for shifting excess heat from summer to winter. Those storages exist and are covered by some models.

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

The word "naturally" _might_ be relevant when distinguishing ambient heat from sub-surface thermal energy storages which are used for shifting excess heat from summer to winter. Those storages exist and are covered by some models.

I just had a vision of Mr. Burns stealing thermal energy from the Springfield storage by drilling lots of secret wells for his clandestine heat pumps. :rofl:
But seriously, that would still be ambient heat. The lines get blurry there, though, and I see clearer and clearer why most models just ignore ambient thermal energy.

[stap-m]

Let's leave "naturally" out. We can still change the def later if needed.

[l-emele]

Leaving out the word "naturally" only shifts the problem. We definitely need that part/share/subclass of ambient heat that has a renewable origin and in my view that is only naturally occurring ambient heat.

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

We definitely need that part/share/subclass of ambient heat that has a renewable origin and in my view that is only naturally occurring ambient heat.

Could you elaborate on that? I fail to see the use case, even less so the need, for this. What process/data can't be annotated without this?

[l-emele]

The use case is that you often want to aggregate renewable energy e.g. to calculate a renewable share. In such a calculation usually only naturally occurring ambient heat is included.

[0UmfHxcvx5J7JoaOhFSs5mncnisTJJ6q]

Please be more specific. What energy flow could be mis-aggregated?

[l-emele]

I already brought a specific example above.

Anyway, we had a consensus in the meeting that explicitly included the word "naturally". If you want to change this consensus, what are your arguments for changing that consensus?

[carstenhoyerklick]

I think naturally should mean the ambient heat that comes either nuclear decay from within the earth or from the sun and weather. I therefore should exclude any artificial heat, as any kind of waste heat that comes from other man made processes. I thinks it makes sense to distiguish between these two.

[stap-m]

What about 2 subclasses: natural ambient heat and e.g. artificial ambient heat? Thus, it becomes possible to distiguish, or not.

[l-emele]

I would be fine with that.

The axiomatic differentiation could be done using has_origin (_x has the origin of y_)? We already have origin (_The origin is a quality that indicates where something comes from (its source)._) and some subclasses of it that are relevant here:

• anthropogenic: _anthropogenic is an origin of portions of matter created by human activity._
• geogenic: _geogenic is an origin of portions of matter that are the result of geological processes._
• renewable: _Renewable is an origin of portions of matter that replenish on a human time scale._

So natural ambient heat energy would get has origin some renewable energy and artificial ambient heat energy would get has origin some anthropogenic? The definitions of these origins would have to be extended to not only cover portions of matter but also energy.

(EDIT: Added the missing energy words).

[stap-m]

So natural ambient heat would get has origin some renewable

both, renewable and geogenic?!

[l-emele]

I would describe geothermal energy (#727) as geogenic, but not the ambient heat energy.

[carstenhoyerklick]

I would agree to that, as heat comming from the near surface ground is mainly influenced by the weather an not by decay processes within Earth. I would therefore for me count as renewable.

[stap-m]

Ready for implementation?