> ## Documentation Index
> Fetch the complete documentation index at: https://docs.transitionzero.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Existing assets

> This page discusses how Scenario Builder uses existing asset data, an essential starting input for energy system modelling.

Every model begins with a snapshot of the current energy system, including all existing generation (power plants), storage (e.g. batteries), and transmission (major power lines) assets. For each asset, the following information is required:

* **Capacity (MW):** The capacity of operating assets in the model’s start year, referred to as ‘Residual Capacity’ in the TZ-OSeMOSYS framework. Assets that are under construction or committed are included in the future system.
* **Location:** Latitude and longitude coordinates.
* **Year of construction:** The commissioning year of the asset.
* **Operational life:** The expected number of years the asset remains in service.

Data sourcing standards for existing assets is detailed below.

# Data sourcing standards – existing assets

| **Input variable**                                                                              | **Model type** | **Gold Standard ('Best in Class')**                                             | **Silver Standard ('Good')**                                                                                   | **Bronze Standard ('Publishable')**                                                                                                             |
| :---------------------------------------------------------------------------------------------- | :------------- | :------------------------------------------------------------------------------ | :------------------------------------------------------------------------------------------------------------- | :---------------------------------------------------------------------------------------------------------------------------------------------- |
| Power plant data - current (location, capacity, fuel, technology, start year, operational life) | CE & UD        | Asset-by-asset validation and gap-filling by TransitionZero’s country analysts. | Asset-by-asset validation.                                                                                     | Global datasets.                                                                                                                                |
| Interconnector data - current (location, capacity, technology, start year, operational life)    | CE & UD        | Asset-by-asset validation and gap-filling by TransitionZero’s country analysts. | [Global Transmission database](https://zenodo.org/records/10870602) with subnational or grid zone gap-filling. | Country-level copper plate from [Global Transmission database](https://zenodo.org/records/10870602), national or subnational level (grid-zone). |