CTM

OPERA is a Dutch-based national energy system model focusing on total system cost minimization. Refer to https://multimodelling.readthedocs.io/en/latest/energy_models/CTM/index.html for more overall information regarding the model.

General model information

General model information questions were asked regarding basic information, model versions, and point of contact for questions. The CTM model is developed and maintained by Kalavasta.

Questions to ask	Answers/Explanation
Model name	CTM (Carbon Transition Model)
Model owner	Kalavasta
Model Developer	Kalavasta
The latest model version/date
The model version used in this project	5th April 2022
Organization	Kalavasta
Individual	Karel Zwetsloot

A second set of questions was asked regarding whether the model is type or token, the intended purpose of the model, and the level of decision that the model aims to support. We understand that the model can be categorized as a token model as it analyzes the feedstock and energy balance of the Dutch energy-intensive industries. The model focuses on large industrial sites and performs bottom-up calculations. The model considers location-specific demand and supply values under different future scenario conditions. The long-term strategy is discussions between industries, grid operators, and the government regarding what energy infrastructure type would be needed for climate neutrality.

Questions to ask	Answers/Explanation
Is the model a token model? If so, give illustration(s).	Yes. The model analyzes the feedstock and energy balance of the energy-intensive Dutch industries per site. The starting point is the major energy and mass consumers in the Netherlands.
Is the model a type model? If so, give illustration(s).
Briefly describe the intended purpose of the model	1. CTM takes large industrial sites and does the calculation bottom-up. 2. Material and energy balance for Dutch energy-intensive industry on a per-site basis. 3. Location-specific demand and supply values under different change scenarios. 4. It could be used for forecasting infrastructure needs, but this is not the primary goal. It can also be used to explore other options given potential transition goals.
Strategic - long-term planning; what do we want?	The long-term strategy of the Dutch energy-intensive industry is included by considering the 2025 – 2050 time frame. For strategic discussion between industry, industry and grid operators, industry and government, and industry and NGOs. For example, from the perspective of TSO/DSOs, what kind of energy infrastructure would be needed depending on plans to go carbon neutral? The model provides a localized, location-specific, scenario-building tool for large energy flows.
Tactical - medium-term; how do we approach this?
Operational - short-term; regular/day-to-day operations?

One of the model’s strengths is the ability to perform energy and mass balance analyses of specific industrial sites. The model has been used to create the II3050 infrastructure outlook for the Dutch industry to provide demand profiles to industrial sites for specific future years, such as 2025 and 2030, based on pre-existing scenarios.

Questions to ask	Answers/Explanation
What are typical types of questions that can be asked to the model? provide examples of such questions
What are the strengths of this model? What is unique?	Specific analysis of mass and energy balance of industrial sites.
What are the important limitations of the model?
Cases/examples where the model was used for its intended purpose	1. Used for the II3050 infrastructure outlook for the Dutch industry to provide demand profiles in industrial sites in 2025, 2030, and 2050 based on four pre-existing scenarios. 2. First Application for II3050 edition 2 together with the 14 largest emitters in the industry, Min. of Economic Affairs and Climate, the Grid Operators, and VNO-NCW. Additional comments/remarks: It could be used for forecasting infrastructure needs, but this is not the primary goal. It can also be used to explore other options given potential transition goals.
Cases/examples where the model was not used for its intended purpose; are there any examples of model abuse or misuse?

The next set of questions is related to model documentation, accessibility, and type. The model documentation is not complete. The graphical user interface (GUI) is available online. The model is static, continuous, and deterministic. The model is not an optimization model.

Questions to ask	Answers/Explanation
Is the model documentation complete?	No
Is the documentation accessible? If so, how?	Some documentation is available online.
Is the documentation in English?	Not available
Does the model have a GUI? If so, how to access it?	Yes, online https://carbontransitionmodel.com/
Does the model have an Application Programming Interface (API) ? If so, how to access it?
Is the model static or dynamic?	Static
Is the model continuous or discrete?	continuous
Is the model stochastic or deterministic?	Deterministic
Is it an optimization model? If so, what type of algorithms it uses?	No

The next set of questions are regarding the modeling paradigm, implementation environment, and license. The model applies multiple formalisms, such as one-shot calculations, mass and energy flow-based calculations, mathematical expressions and equations, and graph or network-based calculations. The model uses JAVA-based web applications for online spreadsheets. The model is implemented in Excel spreadsheets. Therefore, no specific license is required to run the model.

Questions to ask	Answers/Explanation
What modeling paradigm or formalism does the model use?	1. One-shot calculation and mass and energy flow-based calculations Mathematical expressions and equations Graph (or network) based.
Is it implemented in a General purpose programming language?	1. Python orchestrator and API application (connects the frontend and the web access) 2. JAVA-based web application for online spreadsheets (Keikai - API) - AWS input/output for the spreadsheet model 3. The user interface in HTML and JS (front end) Additional comments/remarks: Operating system: Windows for now, AWS container, Mac soon available
Does it use a modeling/Simulation environment/package?
Is it implemented in a spreadsheet?	Excel model
Is any license required to run the model?	No

Model content

A preliminary set of model content questions were related to energy system integration and scope. The model does not represent an integrated energy system. The model fully covers industries; however, heat integration is still in development.

Essential elements and concepts the model includes are most energy carriers used by Dutch industries, such as Electricity, natural gas, hydrogen, heat, and others (including different types of methane, biowaste/non-biowaste, biomass, waste, carbon monoxide, etc.). No specific attention is paid to including flexibility options.

Questions to ask	Answers/Explanation
Does the model represent an integrated energy system?	No Additional comments/remarks: Fully integrated for industries, heat integration is still in development
What important elements and concepts are included in the model?	1. Energy carriers: Electricity, natural gas, hydrogen, heat, and others (including different types of methane, biowaste/non-biowaste, biomass, waste, carbon monoxide, etc.) 2. A carbon pricing system is in place. 3. The model considers spatial data regarding grid connections (H2, electricity, CO2, and gas). Distance is considered for heat transportation.
What elements and concepts are currently not included in the model, but in your opinion, those shall be included?
Specific attention to flexibility options: What type of flexibility options are included in the model?	No

The next set of content-related questions included scale and resolution. The spatial scale of the model is the national level, and the temporal scale is one future target year, approximately 30 years ahead. The spatial resolution is industry site or cluster level.

Questions to ask	Answers/Explanation
What spatial (or geospatial) scale does the model have?	National
What temporal (or time) scale does the model have?	One target year. Approx. 30 years ahead. Though the year is arbitrary
Spatial resolution	Industry site level or Industry cluster level
Temporal resolution

The next set of questions is related to model assumptions, model inputs, parameters, and outputs, and data sources related to the model. One of the critical assumptions is that material and energy balance need to add up for every industrial site. Industries emitting <100 kT CO2 are not included in the analysis. Electricity production is not included, but facilities having their own power production are included in the analysis. One may contest the level of detail in describing a site. Some mass/energy streams might be missed. Some important model inputs are the costs of energy carriers, investments in technologies, annualized investment costs, costs of carbon emissions (the carbon pricing system is in place), and the infrastructure cost at the national level. Similarly, some important model outputs are emissions, demand, cost, etc., at the cluster, sector, and national levels.

Questions to ask	Answers/Explanation
What critical assumptions does the model have?	1. For every industrial site, a material and energy balance needs to add up. Sites are networked together. So, a network of mass-balanced elements. 2. There is a cut-off of the size of facilities included, namely <100kT CO2 is considered too small. Electricity production is usually not included; some facilities have power generation of their own, which is generally included. Project consortium and expert estimate driven. To illustrate, some smaller sites than the cutoff are included as they are project partners.
Which ones are likely to be contested by others? Why?	Base year assumptions for site activity are approximations made using the best available data. 10-15 main activities are considered. One may contest specific data on the operation of the elements, not their presence. The level of detail in describing the site can be contested. In addition, some mass/energy streams are missed.
What is/are the model input format(s)?
What is/are the model output format(s)?
What are the important model inputs?	1. Site setting, national setting, economic interaction within a pool, and technological inputs for industries 2. Costs of carriers and investments in technologies, annualized investment costs, costs of carbon emissions (carbon pricing system is in place), infrastructure cost (National)
What important parameters does the model have?	Technological, energetic, and financial parameters related to industries
What are the important model outputs?	Emissions, demand, cost, etc., at cluster, sector, and national level
What are the data sources used by the model?
Any data that can be shared? If so, what and how to access them?

Continuing with the model content, there were questions regarding verification, validation, and test, and uncertainty descriptions. There is limited testing on verification, validation, and testing within the model. Mass balance checking could be implemented in Excel. One of the validation methods is feedback from industrial partners, i.e., the qualitative method. Similarly, base year data is matched with publicly available data.

Questions to ask	Answers/Explanation
Can you comment on the test coverage of the model?
What is being verified, validated, or tested in the model?	Limited testing Additional comments/remarks: Mass balance checking could be implemented in Excel
What methods are used for the model verification, validation, and testing, if any?	1. Qualitative method: feedback from industrial partners 2. Quantitative method: face validation, i.e., checking with industrial sites and matching base year data to public data
Can you comment on the uncertainty in model parameters?
Can you comment on the uncertainty in model input?
Can you comment on the uncertainty in the model structure?