Models also consider new assets that could be built in the future, including:

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Committed / Under Construction Assets

A ‘committed’ status typically signifies that the asset has secured all necessary financial, regulatory, and contractual approvals and is officially scheduled for construction or commissioning. An ‘under construction’ status indicates that the asset is currently being built. These assets are typically forced into the model under certain scenarios (e.g. ‘Current Policies’ or ‘Net Zero’), or even regardless of scenario, since their construction is already committed. Users retain the flexibility to include or exclude committed assets from a scenario. For a region or country with asset-level modelling in their regional model, committed assets are included as a separate fleet with zero installed capacity. This allows the model to account for their future operation while taking into account the capital expenditure associated with committed assets coming online, and prevents underestimating total system cost. There are several ways to include committed assets in a scenario:

• Setting their capacity as a scenario’s Minimum Additional Capacity forces that capacity into the model, guaranteeing it is built.
• Setting their capacity as a scenario’s Maximum Additional Capacity makes that capacity available without forcing it, allowing the model to build up to that amount — useful for representing possible delays.
• Setting their capacity as both a scenario’s Minimum Additional Capacity and Maximum Total Capacity guarantees the committed capacity is built, while capping how much additional capacity can be built beyond it. This combination is typically used for the ‘Current Policies’ scenario.

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Potential Assets

Candidate power plants, storage, or transmission lines that the model may choose to build if they are economically optimal. Data for planned and candidate future assets is similar to existing assets:

• Capacity (MW)
• Location (potential sites or region/node)
• Planned year of operation (for committed assets)
• Operational life (Years)
• Technology type
• Fuel type

Data sourcing standards for future assets is detailed below.

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Data sourcing standards – future assets

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Maximum capacity of future assets

Future assets are separated from the existing asset fleet in the model, and are only built if they are economically optimal. They are named as generic “candidate” assets (e.g. “additional_photovoltaic” and “additional_onshore-wind”). The maximum capacity of these candidate assets is an input to the model. The model will not build more than this maximum capacity, even if it is economically optimal to do so. This maximum can be based on:

• Resource availability: e.g., wind and solar potential.
• Policy targets: e.g., renewable energy capacity targets.

If a country or region allows a technology to be built in the future on top of the existing fleet, the maximum capacity of that technology must be specified as the remaining potential (i.e. the total resource or policy-driven potential, minus the existing capacity of assets that already draw on the same commodity or source). This avoids double-counting: without subtracting the existing fleet, the model could end up building more of a resource than is actually available. If a technology’s total potential is only available at the national level, the remaining potential is first calculated nationally (as described above), and then distributed across regions according to each region’s share of current installed capacity for that technology. Existing assets have their potential set equal to their installed capacity, so they cannot be expanded by default. Any new capacity is represented by these generic candidate assets instead.