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Overview of ACES Model Updates

After over a year of stakeholder engagement and feedback collection, the modelling team at Net Zero Atlantic has made several updates to improve the functionality and utility of the ACES model. Below is a summary of the key updates to ACES Model Version 2, released April 2023. For a full explanation of the model updates, please refer to the new User Guide and Technical Documentation.

Updated Model Functions

  • The ability to implement a Renewable Portfolio Standard (RPS) has been added to the model. The base model databases include pre-set RPSs for Nova Scotia and New Brunswick to reflect their existing legislation (e.g., in New Brunswick, 40% of electricity used to meet electricity demand in the province must be procured from renewable energy sources).
  • In addition to setting an emission limit for each region and time period, emission limits can now be set for individual sectors. For example, an emission limit can be set for the transportation sector in Nova Scotia from 2030-2050 or the buildings sector in Prince Edward Island for 2025-2035.
  • Model users can now define intra-annual variations in technology efficiencies. This will enable users to account for variations in efficiencies that certain technologies can experience as a result of changes in temperature (e.g., a heat pump will not operate with the same efficiency on a very cold day in February as it would on a mild day in April). In the base model databases, intra-annual variations of efficiency have been defined for heat pumps, electric vehicles, and plug-in hybrid vehicles.
  • Intra-annual variations can now be added to variable costs. This allows for a more accurate representation of the costs of imported electricity and/or fuels, which fluctuate throughout the year. Historical data have been used to define the intra-annual variations in natural gas and electricity imports in the base model databases.
  • Users can now set an annual additional capacity limit for technologies (e.g., a user can limit the number of new heat pumps that can be added within a defined time period).
  • Model users can now set a maximum and minimum activity and aggregate capacity across all technologies belonging to a group (e.g., setting a maximum activity on all diesel cars). Users can also set a maximum and minimum share of capacity and share of new capacity for a technology in a group (e.g., setting a constraint that would require electric vehicles to make up 30% of new passenger car sales by 2030).
  • The amount of energy that asynchronous generators (e.g., wind turbines) can contribute to the electricity system at a given time can now be limited. This functionality can be used by the model user to reflect operational constraints of the electricity grid.

New Parameters

The new model functionalities described above have been enabled by the addition and/or adjustment of the model parameters that are listed below. To utilize new model functionalities, model users can manipulate the data that are used to define these parameters in the base model databases.  

  • Use CostVariableVariable to set intra-annual variation of variable costs, in addition to the existing CostVariable parameter which is indexed by years – meaning it sets the annual average variable cost.
  • Use DemandSpecificDistribution to vary the end-use demand for a given demand commodity across distinct model years.
  • Use EfficiencyVariable to set efficiency values indexed by timesteps, allowing intra-annual variation of technology efficiency, as opposed to indexed by years (annual) as in the Efficiency table.
  • Use CapacityFactorProcess to include technology vintage when considering capacity factor, allowing for inclusion of technology improvements over time.
  • Use MaxAnnualCapacityFactor and MinAnnualCapacityFactor to set a maximum and minimum annual capacity factor for a technology.
  • Use EmissionLimit to constrain emissions across sectors (e.g., placing an emission limit on transportation), in addition to limiting emissions per region and year.
  • Use MaxNewCapacity and MinNewCapacity to set a maximum and minimum amount of new capacity than can be added in year for a technology.
  • Use MaxActivityGroup and MinActivityGroup to set a maximum and minimum activity across all technologies belonging to a group.
  • Use MaxCapacityGroup and MinCapacityGroup to set a maximum and minimum aggregate capacity across all technologies belonging to a group.
  • Use MaxNewCapacityGroup or MinNewCapacityGroup to set a maximum and minimum amount of new aggregate capacity across all technologies belonging to a group.
  • Use MaxCapacityShare and MinCapacityShare to set a maximum and minimum share of capacity for a technology in a group of technologies.
  • Use MaxNewCapacityShare and MinNewCapacityShare to set a maximum and minimum share of new capacity for a technology in a group.
  • Use MaxAsynchronousShare to set the maximum share that asynchronous generators can provide in a time period.
  • Use Output_Duals to view tabulated output values of all dual variables in the model.
  • Use Output_VStorageSOC to view tabulated stage-of-charge of storage technologies in each timestep.

For a full list of all parameters, please see our updated User Guide and Technical Documentation.