Generator Max Units Retired

Units:	-
Mode:	Input Only
Multi-band:	False
Default Value:	0
Validation Rule:	≥0
Key Property:	No
Description:	Maximum number of units automatically retired in aggregate over the planning horizon

Generator Max Units Retired is the maximum number of units automatically retired in aggregate over the planning horizon by LT Plan. The cost of retiring a unit is given by Retirement Cost. The unit(s) must exist at some time in the planning horizon for there to be retirements i.e. you must define either Units (retiring existing units) or Max Units Built (building and retiring units in the same run).

Table 1: Max Units Retired Example
Generator	Property	Value	Units
Old Coal	Units	1	-
Old Coal	Max Capacity	500	MW
Old Coal	FO&M Charge	50	$/kW/year
Old Coal	Max Units Retired	1	-
Old Coal	Retirement Cost	10000	$000

Max Units Retired can also be used to retire a stage of a multi-stage build as in the following example:

Table 2: CCGT Staging Example
Generator	Property	Value	Units
CCGT Stage 1	Units	0	-
CCGT Stage 1	Max Capacity	90	MW
CCGT Stage 1	Max Units Built	2	-
CCGT Stage 1	Build Cost	1200	$/kW
CCGT Stage 1	Economic Life	25	years
CCGT Stage 1	WACC	10	%
CCGT Stage 1	Max Units Retired	2	-
CCGT Stage 2	Units	0	-
CCGT Stage 2	Max Capacity	355	MW
CCGT Stage 2	Max Units Built	1	-
CCGT Stage 2	Build Cost	700	$/kW
CCGT Stage 2	Economic Life	25	years
CCGT Stage 2	WACC	10	%

Here the Generator "CCGT Stage 1" represents the first stage of CCGT, being two open-cycle gas turbines. "CCGT Stage 2" is the second stage when the heat recovery steam turbine is added. The two Generator build and retire decisions must be linked logically by Constraints using the coefficients Units Built Coefficient, Units Retired Coefficient, Units Built in Year Coefficient, and Units Retired in Year Coefficient as described in the article Capacity Expansion Planning.