Energy as a disposition? Using BFO at its full extent.

Description of the issue

I have been busying myself on trying to understand BFO better in the last few weeks and some major issues have arisen during the process. The topics in this issue imply very drastic changes on the ontology so I don't really expect them to produce some implementation in the short term. If possible lets discuss this in our presence meeting this week, but we have a tight agenda so we might do it in other occasion. I am going to list some of the issues but I think this is not exhaustive. I will propose pairs of issues and solutions:

Energy as a quality

This one is probably the one that has been worrying me the most. We define energy as:

definition "Energy is a quality of material entities which manifests as a capacity to perform work (such as causing motion or the interaction of molecules)"

At one side we have qualities which per definition do not require further processes to be realized but then we have the usual definition that states that energy is the capacity to perform work. These concepts go very deeply into the fundamental components of an ontology, energy is pretty much in every material entity and it has relevance in two contexts: potentiality, namely everything related to storage and potential energy; and actual which is when energy is considered in context of the material entities performing change. The former is realizable in the latter.

Solution: Energy as a disposition

Energy is a realizable entity. Even in its latent state there is a possibility, even if small that it performs some transformation in its material entity and its surroundings. So I would suggest something like:

energy: "Energy is a disposition of material entities to ~participate in processes that~ change the state (physical and/or chemical properties, position) of itself and entities in the system it is part of(work, transformation)"

transformation: "Transformation is a process whose participants change their (physical) states." alternative term: work

With this proposal I would suggest against: https://github.com/OpenEnergyPlatform/ontology/issues/1654

Energy transfer

We currently have a problem with energy transfer not properly differentiating from energy transformation. And I think that the solution using this framework is trivial.

energy transfer: Energy transfer is a transformation with at least two participants(system) where a reduction of energy in of one or more participants is complemented by an equivalent increase in one or more participants within the same system.

For instance:

energy loss: Energy loss is a transformation where there is a reduction of energy of its participants with no equivalent increase among them.

energy gain: Energy gain is a transformation where there is an increase of energy of its participants with no equivalent decrease among them.

The last two make sense only if we think about energy systems!! This means that as long as we define a system, there is no problems of energy coming from or going to nowhere. With this model we also avoid having weird edge cases related to losses in energy transfer.

Energy as disposition excludes many forms in which energy is considered.

If we see energy as a disposition. We will then often refer to energy as latent energy or instantaneous energy, or the quantification of the potential change that the material entity can exert. But when we discuss things like electricity transmission, conduction, radiation etc. we often also refer to the same units of energy. These, I would say are part of the realization of the other forms of energies. In principle these should be associated not to the entities bearing them but the processes in which they are flowing.

Here is where the concept of process profile comes into play.

elucidation "b process_profile_of c holds when b proper_occurrent_part_of c& there is some proper_occurrent_part d of c which has no parts in common with b & is mutually dependent on b& is such that b, c and d occupy the same temporal region (axiom label in BFO2 Reference: [094-005])"@en

Lets take for example the process of heat transfer. Using our new definition of energy transfer there is no changes in its definition. But the meaning changes a little

heat transfer: Heat transfer is an energy transfer of thermal energy.

In an instance of heat transfer process we imply that we have a participating system(a material entity) of, for example, two bodies A and B. At time 0 there is only latent thermal energy in each one of them where A is higher than B, thus creating a differential. This differential allows the flow of heat from A to B until time n where they are found in an equilibrium.

There are a lot of things happening at the same time in this process. Namely, the atoms of A move slower, the atoms of B move faster. Their respective temperatures increase/deacrease etc. The instantatneous changes at each time t0, t1, t2... tn have their own characteristics, which can be expressed by the different states of the objects in the system at each one of the instants. These different independent changes are what we would call process profiles of the a heat transfer process. And they are what we usually measure, estimate and plot to represent the process. These profiles are what we ultimately associate with things like instantaneous energy transfer or power.

But what about the input/output constructs related to Transformation?

This has been also been bothering for a while. The RO defines input(and output as):

definition "p has input c iff: p is a process, c is a material entity, c is a participant in p, c is present at the start of p, and the state of c is modified during p."

definition "p has output c iff c is a participant in p, c is present at the end of p, and c is not present in the same state at the beginning of p."

This means that this relation already has material entities within scope. So what we do by defining transformation is further specifying processes that exclusively transform its material entities. By the way, at least for input has_physical_input seems to be redundant since in this context.

There is no solution necessary for this, I think it is automatically congruent, we should just take into account that this excludes from transformation anything that implies changes in non-physical entities.

The problem arises with the relation we call has_energy_participant and its cousins. Energy being a dependent continuant, can't participate in the process itself. The reason I think this is problematic is because this allows for suspicious models when axiomizing processes. For example

(someCoal is_a materialEntity)
(somePortionofAir is_a materialEntity)
(someChemicalEnergy is_a energy) -> The chemical bonds in a piece of coal
(someKineticEnergy is_a energy)  -> The kinetic energy of a portion of air 
(combustion is_a transformation) -> Combusion is a process, has temporal parts.
(participates_in someCoal combustion)
(participates_in somePortionofAir combustion)
(participates_in someChemicalEnergy combustion) <- Does this imply that the energy participates independently of its bearer? Since this is not possible, this would imply that participates_in is transitive in respect to has_characteristic?
(participates_in someKineticEnergy combustion)

Workflow checklist

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

I am aware that

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

This is turning slowly into a paper 😅

Be aware that we already have a conference paper on this exact topic: https://ceur-ws.org/Vol-3249/paper1-Ensusto.pdf

EDIT: Please be also aware that we are not creating a physics ontology but an energy modelling ontology. Therefore we neglect some physical aspects.

FYI, Energy on a more fundamental level will also be topic of a FOIS paper that I am going to submit together with @fabianneuhaus. I'd be happy to discuss this in more detail in Hannover, if you want.

I have an even better definition that, in my opinion makes the model very robust.

energy: "Energy is a disposition of material entities to change the state of itself and entities in the system it is part of by virtue of its current state."

And I would suggest adding state:

state: "State is a quality of a material entity consisting of the mereological sum of its physical qualities." State roughly adapted from thermodynamics: https://en.wikipedia.org/wiki/Thermodynamic_state

The "mereological sum" part allows things like temperature, state of matter, pressure and other physical properties associated with energy to be part of the quality state which reflect it and influence the disposition.

Another key element is "by virtue of its current state" or "on the basis of its current state". This excludes models like "The disposition of Fido to run away." or "The disposition of a plant to grow". But allows things like "The disposition of this stove to heat my food" and "The instantaneous disposition of a portion of salt to dissolve in water" Enthalpy of solvation. After the process that realizes the energy is finished a new state is achieved with opens new dispositions, namely forms of energy.

This is a model that is both compatible with SNAP and SPAN views of energy Grenon & Smith because of the properties of occurrents where they can have temporal parts. The SNAP view can be viewed as the infinitely small view of system dynamics often found in thermodynamics and the SPAN view is such as the one used in energy systems modelling where energy transformation is viewed as an input/output process.

What about energy converting components? Until now we have been allowing both objects and processes be domain of the has input/output properties. This opens the ontology for very severe ambiguities. Since these components are already participating in energy transformation processes, these relations are not even necessary! Instead we can rely yet again on dispositions, more specifically on functions.

Where energy carriers have the disposition to change in specific ways (energy), energy converting components and energy converting units have the function of changing in a specific way, for example by generating electricity. Since we have system and object aggregate as a material entities, this function can work without friction with the model as things like power plants or household systems can be evaluated in composition with the energy carriers.

We already have energy transformation so we can lean down our definitions a lot.

Old:

'energy converting component': "An energy converting component is an artificial object that is usually a discrete part of an energy transformation unit with the function of transforming, transferring or changing a certain type of energy."

New:

'energy converting component': "An energy converting component is an artificial object with an energy transformation function."

elucidation: "An energy converting component is usually a discrete part of an energy transformation unit"

We can spare us the last part by properly classifying an energy transformation unit as an object aggregate.

Old:

'energy transformation unit': An energy transformation unit is an artificial object that transforms, changes or transfers a certain type of energy.

New:

'energy transformation unit': An energy transformation unit is a object aggregate with an energy transformation function.

This should be materialized in the proper changes in the subclasses:

Old:

combined heat and power plant: "A combined heat and power plant (CHPP) is an energy transformation unit that consists of combined heat and power generating units, a grid component feeding electric energy into an electricity grid, and a grid component feeding thermal energy into a heating grid."

New:

combined heat and power plant: "A combined heat and power plant (CHPP) is an energy transformation unit whose parts consists of at least a combined heat and power generating units, a grid component feeding electric energy into an electricity grid, and a grid component feeding thermal energy into a heating grid."

comment: combined heat and power plants usually have both the electricity generation function and heat generation function

We could consider forcing the CHPP to have both the parts and the functions as musts, but since they have components with these functions as parts this is not necessary.

Some potential energy sub-classes rewording with disposition in mind:

chemical energy:"Chemical energy is energy ~that is stored in~ of the chemical bonds of a substance, ~which can be released by~ it is realized in a chemical reaction."

conventional energy: "Conventional energy is energy whose bearer has conventional origin."

(it is also realized in a chemical reaction which can be combustion, pyrolisis, gasification etc.)

electrical energy: "Electrical energy is ~a form of~ energy ~derived~ from ~the potential or kinetic energy of~ charged particles, it is realized in some electrical current."@en

Origins are a hard thing, but in the context of energy I would tend to associate them to the processes in which they are realized. Some construct which says a renewable process is such a process in which its participants are of renewable origin, or nuclear process(fission, fusion) is such in which nuclear binding energy is realized.

speaking of

nuclear binding energy: "Nuclear binding energy is the energy ~that is~ required to disassemble the nucleus of an atom into its component parts. It is realized in a nuclear reaction"@en

~>'potential energy': potential energy IS a quality~

'potential energy': "Potential energy is the energy that a material entity contains due to its position relative to other material entities or to stresses within itself."

'radiative energy': "Radiative energy is energy realized by radiation processes."

'solar energy': "Solar energy is radiative energy whose bearer is the sun."

I would tend to drop 'renewable energy' in favor of renewable process, or renewable energy transformation.

renewable energy transformation: "A renewable energy transformation is an energy transformation whose participants are of renewable origin."

"thermal energy": "Thermal energy is energy that a material entity contains in the undirected motion of its constituent parts (e.g. molecules and atoms). It is realized in heat transfer"@en alternative label: heat

This last one was hard

And if we were to use this model, energy carrier disposition is in an awkward place. If energy is a disposition then practically everything can have energy. Which is the case!!! In this framework energy carriers are those from which we can extract useful energy which is not just a disposition but a function.

'energy carrier function': definition "An energy carrier ~disposition~ function is a ~function~ of a material entity to hold energy for realization in a future time ."@en

And we can also clean up that way the renewable energy carrier disposition. Which right now allows super weird models. For example:

A is a material object which bears some renewable energy. A has origin conventional but the energy it bears has origin renewable. I am not saying that is completely illogical, you could store heat from a heat pump into a bed of coal I guess but this dependant continuants depending on dependant continuants could lead to a lot of problems.

I would tend to drop 'renewable energy' in favor of renewable process, or renewable energy transformation.

renewable energy transformation: "A renewable energy transformation is an energy transformation whose participants are of renewable origin."

One might wonder, what happens when I want to talk about renewable energy. For that we should understand how the concept is used. And I think there some clear usages where other terms can be very helpful.

In the case renewable energy capacity for example, I would make it a subclass of potential energy which is a quality.

energy potential: "Energy potential is a quality of a material object that quantifies its theoretical energy output."

alternative label: energy, this can be our current implementation of energy.

example: "The calories of an apple"

~potential energy: "Potential energy (physics) is the energy potential that a material entity has due to its position relative to other material entities or to stresses within itself."~

renewable energy potential: "Renewable energy potential is an energy potential of material entities with renewable origin."

In the case of realized energy, for example in national reports of energy supply in a certain month or year, one should refer to the processes in which they were realized.

One speaks of the realized energy output of a process whose participants are of renewable origin, or better not conventional origin.

energy (profile): "Energy (profile) is a process profile of energy transformations."

example: The energy consumed by my household today.

alternatively

produced energy: "Produced energy is a process attribute where the total energy realized in a process is quantified."

alternative label for both: energy, I would prefer the former.

This is one of those examples on the point of using ontologies, language is tricky and when people use a word in different contexts they might mean a different concept.

renewable energy: "Renewable energy is energy (profile) extracted from renewable sources."

And using the vision of energy profile in the previous comment, the definition of Power used by the colleagues in Buffalo fits almost perfectly

https://github.com/CommonCoreOntology/CommonCoreOntologies/blob/a9e8c72eda3e01acbfca3eaaa837b7385d853c8a/EventOntology.ttl#L2256C1-L2263C34

###  http://www.ontologyrepository.com/CommonCoreOntologies/Power
cco:Power rdf:type owl:Class ;
          rdfs:subClassOf obo:BFO_0000144 ;
          cco:definition "A Process Profile that is characterized by the rate of Work, or Energy consumed, done in a given time period."@en ;
          cco:is_curated_in_ontology "http://www.ontologyrepository.com/CommonCoreOntologies/Mid/EventOntology"^^xsd:anyURI ;
          rdfs:label "Power"@en .

I could go longer but I think I will wrap this up here, here is a TL;DR:

There are 3 definitions of energy that play a role in our domain. None is more valid than the other but it would be naive to use a single term for all of them.
The first is the physics definition of science which is in the definition of the current implementation. This makes more sense as a realizable entity and its the "actual" energy.
The second is the quantified definition of energy, probably the most widely used when discussing fuels and food. This is a quality of the material entities and represent potential output. This is how we are using our current implementation.
The third is the realized form of energy. It is what is often discussed when referring to energy consuming/producing processes. For example the energy consumption of all the households of germany or the energy produced by some power plant. This is more fitting as a process profile

OpenEnergyPlatform / ontology