Update thermal decay variables to match electric storage self-discharge

src/constraints/storage_constraints.jl

@@ -111,11 +111,12 @@ function add_hot_thermal_storage_dispatch_constraints(m, p, b; _n="")
 	@constraint(m, [b in p.s.storage.types.hot, ts in p.time_steps],
     m[Symbol("dvStoredEnergy"*_n)][b,ts] == m[Symbol("dvStoredEnergy"*_n)][b,ts-1] + (1/p.s.settings.time_steps_per_hour) * (
         p.s.storage.attr[b].charge_efficiency * sum(m[Symbol("dvHeatToStorage"*_n)][b,t,q,ts] for t in union(p.techs.heating, p.techs.chp), q in p.heating_loads) -
-        sum(m[Symbol("dvHeatFromStorage"*_n)][b,q,ts] for q in p.heating_loads) / p.s.storage.attr[b].discharge_efficiency -
-        p.s.storage.attr[b].thermal_decay_rate_fraction * m[Symbol("dvStorageEnergy"*_n)][b]
+        sum(m[Symbol("dvHeatFromStorage"*_n)][b,q,ts] for q in p.heating_loads) / p.s.storage.attr[b].discharge_efficiency
         )
+        - (p.s.storage.attr[b].soc_based_per_ts_thermal_decay_fraction * m[Symbol("dvStoredEnergy"*_n)][b, ts])
+        - (p.s.storage.attr[b].capacity_based_per_ts_thermal_decay_fraction * m[Symbol("dvStorageEnergy"*_n)][b])
     )
-    
+
     #Constraint (4n)-1: Dispatch to and from thermal storage is no greater than power capacity
 	@constraint(m, [b in p.s.storage.types.hot, ts in p.time_steps],
         m[Symbol("dvStoragePower"*_n)][b] >= 
@@ -154,9 +155,10 @@ function add_cold_thermal_storage_dispatch_constraints(m, p, b; _n="")
 	@constraint(m, ColdTESInventoryCon[b in p.s.storage.types.cold, ts in p.time_steps],
     m[Symbol("dvStoredEnergy"*_n)][b,ts] == m[Symbol("dvStoredEnergy"*_n)][b,ts-1] + (1/p.s.settings.time_steps_per_hour) * (
         sum(p.s.storage.attr[b].charge_efficiency * m[Symbol("dvProductionToStorage"*_n)][b,t,ts] for t in p.techs.cooling) -
-        m[Symbol("dvDischargeFromStorage"*_n)][b,ts]/p.s.storage.attr[b].discharge_efficiency -
-        p.s.storage.attr[b].thermal_decay_rate_fraction * m[Symbol("dvStorageEnergy"*_n)][b]
+        m[Symbol("dvDischargeFromStorage"*_n)][b,ts]/p.s.storage.attr[b].discharge_efficiency
         )
+        - (p.s.storage.attr[b].soc_based_per_ts_thermal_decay_fraction * m[Symbol("dvStoredEnergy"*_n)][b, ts])
+        - (p.s.storage.attr[b].capacity_based_per_ts_thermal_decay_fraction * m[Symbol("dvStorageEnergy"*_n)][b])
     )
 
     #Constraint (4n)-2: Dispatch to and from thermal storage is no greater than power capacity

src/core/energy_storage/thermal_storage.jl

@@ -15,7 +15,8 @@ Cold thermal energy storage sytem; specifically, a chilled water system used to
     soc_min_fraction::Float64 = 0.1 # Minimum allowable TES thermal state of charge
     soc_init_fraction::Float64 = 0.5 # TES thermal state of charge at first hour of optimization
     installed_cost_per_gal::Float64 = 1.50 # Thermal energy-based cost of TES (e.g. volume of the tank)
-    thermal_decay_rate_fraction::Float64 = 0.0004 # Thermal loss (gain) rate as a fraction of energy storage capacity, per hour (frac*energy_capacity/hr = kw_thermal)
+    soc_based_per_ts_thermal_decay_fraction = 0.0 # Thermal loss (gain) rate as a fraction of energy storage capacity per timestep (frac*energy_capacity = kw_thermal); the provided default is for an hourly thermal loss/gain
+    capacity_based_per_ts_thermal_decay_fraction = 0.0004 # Thermal loss (gain) rate as a fraction of the energy storaged in each timestep (frac*energy_stored = kw_thermal)
     om_cost_per_gal::Float64 = 0.0 # Yearly fixed O&M cost dependent on storage energy size
     macrs_option_years::Int = 7
     macrs_bonus_fraction::Float64 = 0.6
@@ -33,7 +34,8 @@ Base.@kwdef struct ColdThermalStorageDefaults <: AbstractThermalStorageDefaults
     soc_min_fraction::Float64 = 0.1
     soc_init_fraction::Float64 = 0.5
     installed_cost_per_gal::Float64 = 1.50
-    thermal_decay_rate_fraction::Float64 = 0.0004
+    soc_based_per_ts_thermal_decay_fraction::Float64 = 0.0
+    capacity_based_per_ts_thermal_decay_fraction::Float64 = 0.0004
     om_cost_per_gal::Float64 = 0.0
     macrs_option_years::Int = 7
     macrs_bonus_fraction::Float64 = 0.6
@@ -55,7 +57,8 @@ end
     soc_min_fraction::Float64 = 0.1
     soc_init_fraction::Float64 = 0.5
     installed_cost_per_gal::Float64 = 1.50
-    thermal_decay_rate_fraction::Float64 = 0.0004
+    soc_based_per_ts_thermal_decay_fraction = 0.0
+    capacity_based_per_ts_thermal_decay_fraction = 0.0004
     om_cost_per_gal::Float64 = 0.0
     macrs_option_years::Int = 7
     macrs_bonus_fraction::Float64 = 0.6
@@ -76,7 +79,8 @@ Base.@kwdef struct HotThermalStorageDefaults <: AbstractThermalStorageDefaults
     soc_min_fraction::Float64 = 0.1
     soc_init_fraction::Float64 = 0.5
     installed_cost_per_gal::Float64 = 1.50
-    thermal_decay_rate_fraction::Float64 = 0.0004
+    soc_based_per_ts_thermal_decay_fraction::Float64 = 0.0
+    capacity_based_per_ts_thermal_decay_fraction::Float64 = 0.0004
     om_cost_per_gal::Float64 = 0.0
     macrs_option_years::Int = 7
     macrs_bonus_fraction::Float64 = 0.6
@@ -105,7 +109,8 @@ struct ColdThermalStorage <: AbstractThermalStorage
     soc_min_fraction::Float64
     soc_init_fraction::Float64
     installed_cost_per_gal::Float64
-    thermal_decay_rate_fraction::Float64
+    soc_based_per_ts_thermal_decay_fraction::Float64
+    capacity_based_per_ts_thermal_decay_fraction::Float64
     om_cost_per_gal::Float64
     macrs_option_years::Int
     macrs_bonus_fraction::Float64
@@ -154,7 +159,8 @@ struct ColdThermalStorage <: AbstractThermalStorage
             s.soc_min_fraction,
             s.soc_init_fraction,
             s.installed_cost_per_gal,
-            s.thermal_decay_rate_fraction,
+            s.soc_based_per_ts_thermal_decay_fraction,
+            s.capacity_based_per_ts_thermal_decay_fraction,
             s.om_cost_per_gal,
             s.macrs_option_years,
             s.macrs_bonus_fraction,
@@ -188,7 +194,8 @@ struct HotThermalStorage <: AbstractThermalStorage
     soc_min_fraction::Float64
     soc_init_fraction::Float64
     installed_cost_per_gal::Float64
-    thermal_decay_rate_fraction::Float64
+    soc_based_per_ts_thermal_decay_fraction::Float64
+    capacity_based_per_ts_thermal_decay_fraction::Float64
     om_cost_per_gal::Float64
     macrs_option_years::Int
     macrs_bonus_fraction::Float64
@@ -240,7 +247,8 @@ struct HotThermalStorage <: AbstractThermalStorage
             s.soc_min_fraction,
             s.soc_init_fraction,
             s.installed_cost_per_gal,
-            s.thermal_decay_rate_fraction,
+            s.soc_based_per_ts_thermal_decay_fraction,
+            s.capacity_based_per_ts_thermal_decay_fraction,
             s.om_cost_per_gal,
             s.macrs_option_years,
             s.macrs_bonus_fraction,

test/scenarios/ghp_inputs.json

@@ -59,11 +59,11 @@
     "ColdThermalStorage": {
         "min_gal": 10,
         "max_gal": 10,
-        "thermal_decay_rate_fraction": 0.0
+        "capacity_based_per_ts_thermal_decay_fraction": 0.0
     },
     "HotThermalStorage": {
         "min_gal": 10,
         "max_gal": 10,
-        "thermal_decay_rate_fraction": 0.0
+        "capacity_based_per_ts_thermal_decay_fraction": 0.0
     }
 }

test/scenarios/heat_cool_energy_balance_inputs.json

@@ -74,13 +74,13 @@
         "min_gal": 20000.0,
         "max_gal": 20000.0,
         "internal_efficiency_fraction": 0.97,
-        "thermal_decay_rate_fraction": 0.004
+        "capacity_based_per_ts_thermal_decay_fraction": 0.004
     },
     "ColdThermalStorage":{
         "min_gal": 30000.0,
         "max_gal": 30000.0,
         "internal_efficiency_fraction": 0.97,
-        "thermal_decay_rate_fraction": 0.004,
+        "capacity_based_per_ts_thermal_decay_fraction": 0.004,
         "soc_init_fraction": 0.1
     },
     "AbsorptionChiller": {

test/scenarios/re_emissions_with_thermal.json

@@ -79,7 +79,7 @@
     "soc_min_fraction": 0.1 ,
     "soc_init_fraction": 0.5 ,
     "installed_cost_per_gal": 3.0 ,
-    "thermal_decay_rate_fraction": 0.004 ,
+    "capacity_based_per_ts_thermal_decay_fraction": 0.004 ,
     "om_cost_per_gal": 0.0 ,
     "macrs_option_years": 0 ,
     "macrs_bonus_fraction": 0.0