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EnergyPathway Concepts

EnergyPathway keeps the Nosy modeling philosophy: build systems from carriers, nodes, components, model archetypes, and reusable behaviors. It adds only the concepts needed to connect snapshots through time.

PathOpt

PathOpt stores the temporal options of a pathway:

  • years: snapshot years, initially empty if no year list is provided.
  • discountrate: discount rate used for pathway costs.
  • baseyear: reference year for discounting.
  • endyear: final model year, which can be after the last snapshot year.
  • mesh: default TimeMesh, or a dictionary of year-specific meshes when years are known up front.
  • ini: optional historical capacity.

The preferred incremental workflow starts without declaring years twice:

using HiGHS

opt = PathOpt()
path = Path(HiGHS.Optimizer, opt)
snap = addsnapshot!(path, 2030)

For compatibility, snapshot years can still be declared up front:

opt = PathOpt(2020:10:2050)

Path

Path owns:

  • one shared JuMP model,
  • one Nosy Sim per snapshot year,
  • one Nosy Snapshot per snapshot year,
  • the dynamic constraints that link snapshots.

Access snapshots with:

snapshot = path[2030]

or:

snapshot = getsnapshot(path, 2030)

Add snapshots with:

snap = addsnapshot!(path, 2030)

or register an existing snapshot that uses the pathway's shared JuMP model:

snap = Snapshot(Sim(model(path), mesh=TimeMesh(), suffix="2030"))
addsnapshot!(path, snap, 2030)

Historical Capacity

Historical capacity is passed with ini. Each entry is:

(year, component_name, capacity, lifetime)

For example:

opt = PathOpt(
    2020:10:2040;
    ini=[
        (2010, "PV", 100, 25),
        (2015, "PV", 200, 25),
    ],
)

Historical capacity must be installed before the first snapshot year and must still be alive at the first snapshot year.

Dynamic Behaviors

EnergyPathway components are ordinary Nosy components with extra behaviors:

  • VariableDeployment creates an optimized deployment variable.
  • FixedDeployment fixes deployment to a given value.
  • VariableRetirement creates an optimized retirement variable.
  • FixedRetirement fixes retirement to a given value.
  • Lifetime defines when capacity must be retired.
  • SingleCost attaches a non-recurring cost to an event.

SingleCost is useful for construction costs, investment costs, connection costs, dismantling costs, or any other cost paid once because a capacity event happens. The type symbol is user-defined, so :capex, :construction, or :grid_connection are all valid tags.

For construction cost, the cost profile can represent payment timing relative to deployment:

SingleCost(:construction, :deployment, "output", energy, 50_000, Dict(-2 => 0.3, -1 => 0.4, 0 => 0.3))

This means 30% of the construction cost is paid two years before deployment, 40% one year before deployment, and 30% in the deployment year. Profile shares must sum to one, and EnergyPathway discounts each payment in its own year.

Dynamic capacity constraints are added only for components that use deployment or retirement behaviors. Ordinary fixed Nosy components remain snapshot-local.

Metrics

The main year-aware pathway metrics are:

capacity(path, "gen", 2030)
deployment(path, "gen", 2030)
retirement(path, "gen", 2030)
singlecost(path, "gen", 2030, :capex)
cost(path, "gen", 2030)

Aggregated forms are also available:

cost(path)
cost(path, "gen")
cost(path, :capex)