Battery

Graph structure

A battery is a storage technology that is represented in Macro by the following graph structure:

%%{init: {'theme': 'base', 'themeVariables': { 'background': '#D1EBDE' }}}%% flowchart LR subgraph Battery direction BT A((Electricity)):::node1 A--Charge--> B[Storage] --Discharge--> A end legend@{img: "../../images/battery.png", w: 120, h: 100, constraint: "off"} Battery ~~~ legend style A r:40,fill:orange,stroke:black,color:black,stroke-dasharray: 3,5; style B fill:orange,stroke:black,color:black; linkStyle 0,1 stroke:orange, stroke-width: 3px; style legend fill:white

Therefore, a battery asset is made of:

1 Storage component, representing the battery storage.
2 Electricity Edge components:
- one incoming representing the charge edge from the electricity network to the storage.
- one outgoing representing the discharge edge from the storage to the electricity network.

Attributes

As for all the other assets, the structure of the input file for a battery asset follows the graph representation. Each global_data and instance_data will look like this:

{
    "storage":{
        // ... storage-specific attributes ...
    },
    "edges":{
        "charge_edge": {
            // ... charge_edge-specific attributes ...
        },
        "discharge_edge": {
            // ... discharge_edge-specific attributes ...
        }
    }
}

where the possible attributes that the user can set are reported in the following tables.

Storage component

The definition of the Storage object can be found here MacroEnergy.Storage.

Attribute	Type	Values	Default	Description
commodity	`String`	`Electricity`	Required	Commodity being stored.
constraints	`Dict{String,Bool}`	Any Macro constraint type for storage	`BalanceConstraint`, `StorageCapacityConstraint`, `StorageSymmetricCapacityConstraint`	List of constraints applied to the storage. E.g. `{"BalanceConstraint": true}`.
can_expand	`Bool`	`Bool`	`false`	Whether the storage is eligible for capacity expansion.
can_retire	`Bool`	`Bool`	`false`	Whether the storage is eligible for capacity retirement.
charge_discharge_ratio	`Float64`	`Float64`	`1.0`	Ratio between charging and discharging rates.
existing_capacity	`Float64`	`Float64`	`0.0`	Initial installed storage capacity (MWh).
fixed_om_cost	`Float64`	`Float64`	`0.0`	Fixed operations and maintenance cost (USD/MWh-year).
investment_cost	`Float64`	`Float64`	`0.0`	Annualized investment cost of the energy capacity for a storage technology (USD/MWh-year).
long_duration	`Bool`	`Bool`	`false`	Whether the storage is a long-duration storage. (Note: if `true`, the model will add the long-duration storage constraints to the storage).
loss_fraction	`Float64`	Number $\in$ [0,1]	`0.0`	Fraction of stored commodity lost per timestep.
max_capacity	`Float64`	`Float64`	`Inf`	Maximum allowed storage capacity (MWh).
max_duration	`Float64`	`Float64`	`0.0`	Maximum ratio of installed energy to discharged capacity that can be installed (hours).
max_storage_level	`Float64`	`Float64`	`1.0`	Maximum storage level as a fraction of capacity.
min_capacity	`Float64`	`Float64`	`0.0`	Minimum allowed storage capacity (MWh).
min_duration	`Float64`	`Float64`	`0.0`	Minimum ratio of installed energy to discharged capacity that can be installed (hours).
min_outflow_fraction	`Float64`	`Float64`	`0.0`	Minimum outflow as a fraction of capacity.
min_storage_level	`Float64`	`Float64`	`0.0`	Minimum storage level as a fraction of capacity.

Default constraints

As noted in the above table, the default constraints for the storage component of the battery are the following:

If the storage is a long-duration storage, the following additional constraints are applied:

Long-duration storage constraints

Charge and discharge edges

Both the charge and discharge edges are represented by the same set of attributes. The definition of the Edge object can be found here MacroEnergy.Edge.

Attribute	Type	Values	Default	Description
type	`String`	`Electricity`	Required	Commodity of the edge. E.g. "Electricity".
start_vertex	`String`	Any electricity node id present in the system	Required	ID of the starting vertex of the edge. The node must be present in the `nodes.json` file. E.g. "elec_node_1".
end_vertex	`String`	Any electricity node id present in the system	Required	ID of the ending vertex of the edge. The node must be present in the `nodes.json` file. E.g. "elec_node_2".
constraints	`Dict{String,Bool}`	Any Macro constraint type for Edges	Empty for charge edge, check box below for discharge edge	List of constraints applied to the edge. E.g. `{"CapacityConstraint": true}`.
can_expand	`Bool`	`Bool`	`false`	Whether the edge is eligible for capacity expansion.
can_retire	`Bool`	`Bool`	`false`	Whether the edge is eligible for capacity retirement.
efficiency	`Float64`	Number $\in$ [0,1]	`1.0`	Efficiency of the charging/discharging process.
existing_capacity	`Float64`	`Float64`	`0.0`	Existing capacity of the edge in MW.
fixed_om_cost	`Float64`	`Float64`	`0.0`	Fixed operations and maintenance cost (USD/MW-year).
has_capacity	`Bool`	`Bool`	`false`	Whether capacity variables are created for the edge.
integer_decisions	`Bool`	`Bool`	`false`	Whether capacity variables are integers.
investment_cost	`Float64`	`Float64`	`0.0`	Annualized capacity investment cost (USD/MW-year)
max_capacity	`Float64`	`Float64`	`Inf`	Maximum allowed capacity of the edge (MW). Note: add the `MaxCapacityConstraint` to the constraints dictionary to activate this constraint.
min_capacity	`Float64`	`Float64`	`0.0`	Minimum allowed capacity of the edge (MW). Note: add the `MinCapacityConstraint` to the constraints dictionary to activate this constraint.
min_flow_fraction	`Float64`	Number $\in$ [0,1]	`0.0`	Minimum flow of the edge as a fraction of the total capacity. Note: add the `MinFlowConstraint` to the constraints dictionary to activate this constraint.
ramp_down_fraction	`Float64`	Number $\in$ [0,1]	`1.0`	Maximum decrease in flow between two time steps, reported as a fraction of the capacity. Note: add the `RampingLimitConstraint` to the constraints dictionary to activate this constraint.
ramp_up_fraction	`Float64`	Number $\in$ [0,1]	`1.0`	Maximum increase in flow between two time steps, reported as a fraction of the capacity. Note: add the `RampingLimitConstraint` to the constraints dictionary to activate this constraint.
unidirectional	`Bool`	`Bool`	`false`	Whether the edge is unidirectional.
variable_om_cost	`Float64`	`Float64`	`0.0`	Variable operation and maintenance cost (USD/MWh).

Efficiency

The efficiency of the charging/discharging process can be set in the charge_edge and discharge_edge parts of the input file. These parameters are used, for example, in the Balance constraint to balance the charge and discharge flows.

Default constraints - discharge edge

The default constraints for the discharge edge are the following:

Example

The following is an example of the input file for a battery asset that creates three batteries, one in each of the SE, MIDAT and NE regions.

{
    "elec_stor": [
        {
            "type": "Battery",
            "global_data": {
                "storage": {
                    "commodity": "Electricity",
                    "can_expand": true,
                    "can_retire": false,
                    "constraints": {
                        "BalanceConstraint": true,
                        "StorageCapacityConstraint": true,
                        "StorageSymmetricCapacityConstraint": true,
                        "StorageMinDurationConstraint": true,
                        "StorageMaxDurationConstraint": true,
                    }
                },
                "edges": {
                    "discharge_edge": {
                        "type": "Electricity",
                        "unidirectional": true,
                        "has_capacity": true,
                        "can_expand": true,
                        "can_retire": false,
                        "constraints": {
                            "CapacityConstraint": true,
                            "StorageDischargeLimitConstraint": true
                        }
                    },
                    "charge_edge": {
                        "type": "Electricity",
                        "unidirectional": true,
                        "has_capacity": false
                    }
                }
            },
            "instance_data": [
                {
                    "id": "battery_SE",
                    "edges": {
                        "discharge_edge": {
                            "end_vertex": "elec_SE",
                            "capacity_size": 1.0,
                            "existing_capacity": 0.0,
                            "fixed_om_cost": 4536.98,
                            "investment_cost": 17239.56121,
                            "variable_om_cost": 0.15,
                            "efficiency": 0.92
                        },
                        "charge_edge": {
                            "start_vertex": "elec_SE",
                            "efficiency": 0.92,
                            "variable_om_cost": 0.15
                        }
                    },
                    "storage": {
                        "existing_capacity_storage": 0.0,
                        "fixed_om_cost_storage": 2541.19,
                        "investment_cost_storage": 9656.002735,
                        "max_duration": 10,
                        "min_duration": 1
                    }
                },
                {
                    "id": "battery_MIDAT",
                    "edges": {
                        "discharge_edge": {
                            "end_vertex": "elec_SE",
                            "capacity_size": 1.0,
                            "existing_capacity": 0.0,
                            "fixed_om_cost": 4536.98,
                            "investment_cost": 17239.56121,
                            "variable_om_cost": 0.15,
                            "efficiency": 0.92
                        },
                        "charge_edge": {
                            "start_vertex": "elec_SE",
                            "efficiency": 0.92,
                            "variable_om_cost": 0.15
                        }
                    },
                    "storage": {
                        "existing_capacity_storage": 0.0,
                        "fixed_om_cost_storage": 2541.19,
                        "investment_cost_storage": 9656.002735,
                        "max_duration": 10,
                        "min_duration": 1
                    }
                },
                {
                    "id": "battery_NE",
                    "edges": {
                        "discharge_edge": {
                            "end_vertex": "elec_SE",
                            "capacity_size": 1.0,
                            "existing_capacity": 0.0,
                            "fixed_om_cost": 4536.98,
                            "investment_cost": 17239.56121,
                            "variable_om_cost": 0.15,
                            "efficiency": 0.92
                        },
                        "charge_edge": {
                            "start_vertex": "elec_SE",
                            "efficiency": 0.92,
                            "variable_om_cost": 0.15
                        }
                    },
                    "storage": {
                        "existing_capacity_storage": 0.0,
                        "fixed_om_cost_storage": 2541.19,
                        "investment_cost_storage": 9656.002735,
                        "max_duration": 10,
                        "min_duration": 1
                    }
                }
            ]
        }
    ]
}