Costing Unification: parameter consistency across costing packages (#…

…1174)

* redefining factor_maintenance_labor_chemical as fraction of total equipment cost

* using higher-level parameters in ZO Costing Package

* consistent expressions / vars across both costing packages

* update CSTR baseline

---------

Co-authored-by: Ludovico Bianchi <lbianchi@lbl.gov>

docs/technical_reference/costing/watertap_costing.rst

@@ -128,7 +128,7 @@ Technoeconomic factors used to calculate various system metrics, capital, and op
 =============================================  ====================  =======================================  ===============  ==============================================================================
 Plant capacity utilization factor                 :math:`f_{util}`    ``utilization_factor``                   90%             Percentage of year plant is operating
 Total investment factor                           :math:`f_{toti}`    ``factor_total_investment``              2.0             Total investment factor (investment cost / equipment cost)
-Maintenance-labor-chemical factor                 :math:`f_{mlc}`     ``factor_maintenance_labor_chemical``    0.03            Maintenance, labor, and chemical factor (fraction of investment cost / year)
+Maintenance-labor-chemical factor                 :math:`f_{mlc}`     ``factor_maintenance_labor_chemical``    0.03            Maintenance, labor, and chemical factor (fraction of equipment cost / year)
 Captial annualization factor                      :math:`f_{caf}`     ``factor_capital_annualization``         0.1             Capital annualization factor (fraction of investment cost / year) 
 Capital recovery factor                           :math:`f_{crf}`     ``capital_recovery_factor``              0.1             Identical to `factor_capital_annualization`
 =============================================  ====================  =======================================  ===============  ==============================================================================
@@ -166,3 +166,4 @@ Class Documentation
 -------------------
 
 * :class:`WaterTAPCostingData`
+

watertap/costing/tests/test_zero_order_costing.py

@@ -411,12 +411,10 @@ def test_process_costing(self, model):
         assert isinstance(model.fs.costing.aggregate_flow_electricity, Var)
         assert isinstance(model.fs.costing.aggregate_flow_costs, Var)
 
-        assert isinstance(model.fs.costing.land_cost, Var)
-        assert isinstance(model.fs.costing.working_capital, Var)
+        assert isinstance(model.fs.costing.land_cost, Expression)
+        assert isinstance(model.fs.costing.working_capital, Expression)
         assert isinstance(model.fs.costing.total_capital_cost, Var)
 
-        assert isinstance(model.fs.costing.land_cost_constraint, Constraint)
-        assert isinstance(model.fs.costing.working_capital_constraint, Constraint)
         assert isinstance(model.fs.costing.total_capital_cost_constraint, Constraint)
 
         assert_units_consistent(model.fs)
@@ -451,34 +449,12 @@ def test_initialize(self, model):
 
         model.fs.costing.initialize()
 
-        assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.land_cost_constraint
-        )
-        assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.working_capital_constraint
-        )
         assert pytest.approx(0, abs=1e-5) == value(
             model.fs.costing.total_capital_cost_constraint
         )
 
         assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.salary_cost_constraint
-        )
-        assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.benefits_cost_constraint
-        )
-        assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.maintenance_cost_constraint
-        )
-        assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.laboratory_cost_constraint
-        )
-        assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.insurance_and_taxes_cost_constraint
-        )
-
-        assert pytest.approx(0, abs=1e-5) == value(
-            model.fs.costing.total_fixed_operating_cost_constraint
+            model.fs.costing.total_operating_cost_constraint
         )
 
     @pytest.mark.solver

watertap/costing/watertap_costing_package.py

@@ -42,7 +42,7 @@ def build_global_params(self):
         )
         self.factor_maintenance_labor_chemical = pyo.Var(
             initialize=0.03,
-            doc="Maintenance-labor-chemical factor [fraction of investment cost/year]",
+            doc="Maintenance-labor-chemical factor [fraction of equipment cost/year]",
             units=pyo.units.year**-1,
         )
         self.factor_capital_annualization = pyo.Var(
@@ -59,42 +59,38 @@ def build_process_costs(self):
         # add total_captial_cost and total_operating_cost
         self._build_common_process_costs()
 
-        self.maintenance_labor_chemical_operating_cost = pyo.Var(
-            initialize=1e3,
-            doc="Maintenance-labor-chemical operating cost",
-            units=self.base_currency / self.base_period,
-        )
-
         self.total_capital_cost_constraint = pyo.Constraint(
             expr=self.total_capital_cost
             == self.factor_total_investment * self.aggregate_capital_cost
         )
-        self.maintenance_labor_chemical_operating_cost_constraint = pyo.Constraint(
-            expr=self.maintenance_labor_chemical_operating_cost
-            == self.factor_maintenance_labor_chemical * self.total_capital_cost
+
+        self.maintenance_labor_chemical_operating_cost = pyo.Expression(
+            expr=self.factor_maintenance_labor_chemical * self.aggregate_capital_cost,
+            doc="Maintenance-labor-chemical operating cost",
+        )
+
+        self.total_fixed_operating_cost = pyo.Expression(
+            expr=self.aggregate_fixed_operating_cost
+            + self.maintenance_labor_chemical_operating_cost,
+            doc="Total fixed operating costs",
         )
 
-        if (
-            pyo.units.get_units(sum(self.aggregate_flow_costs.values()))
-        ) == pyo.units.dimensionless:
-            self.total_operating_cost_constraint = pyo.Constraint(
-                expr=self.total_operating_cost
-                == self.maintenance_labor_chemical_operating_cost
-                + self.aggregate_fixed_operating_cost
-                + self.aggregate_variable_operating_cost
-                + sum(self.aggregate_flow_costs.values())
-                * self.base_currency
-                / self.base_period
+        self.total_variable_operating_cost = pyo.Expression(
+            expr=(
+                self.aggregate_variable_operating_cost
+                + sum(self.aggregate_flow_costs[f] for f in self.used_flows)
                 * self.utilization_factor
             )
-        else:
-            self.total_operating_cost_constraint = pyo.Constraint(
-                expr=self.total_operating_cost
-                == self.maintenance_labor_chemical_operating_cost
-                + self.aggregate_fixed_operating_cost
-                + self.aggregate_variable_operating_cost
-                + sum(self.aggregate_flow_costs.values()) * self.utilization_factor
-            )
+            if self.used_flows
+            else self.aggregate_variable_operating_cost,
+            doc="Total variable operating cost of process per operating period",
+        )
+
+        self.total_operating_cost_constraint = pyo.Constraint(
+            expr=self.total_operating_cost
+            == (self.total_fixed_operating_cost + self.total_variable_operating_cost),
+            doc="Total operating cost of process per operating period",
+        )
 
         self.total_annualized_cost = pyo.Expression(
             expr=(
@@ -108,10 +104,6 @@ def initialize_build(self):
         calculate_variable_from_constraint(
             self.total_capital_cost, self.total_capital_cost_constraint
         )
-        calculate_variable_from_constraint(
-            self.maintenance_labor_chemical_operating_cost,
-            self.maintenance_labor_chemical_operating_cost_constraint,
-        )
         calculate_variable_from_constraint(
             self.total_operating_cost, self.total_operating_cost_constraint
         )

watertap/costing/zero_order_costing.py

@@ -121,6 +121,11 @@ def build_global_params(self):
             / self.base_period
         )
 
+        self.factor_total_investment = pyo.Expression(
+            expr=1.0 + self.working_capital_percent_FCI + self.land_cost_percent_FCI,
+            doc="Total investment factor [investment cost/equipment cost]",
+        )
+
         # Fix all Vars from database
         for v in global_params:
             try:
@@ -141,97 +146,71 @@ def build_process_costs(self):
         self._build_common_process_costs()
 
         # Other capital costs
-        self.land_cost = pyo.Var(
-            initialize=0,
-            units=self.base_currency,
+        self.land_cost = pyo.Expression(
+            expr=self.land_cost_percent_FCI * self.aggregate_capital_cost,
             doc="Land costs - based on aggregate capital costs",
         )
-        self.working_capital = pyo.Var(
-            initialize=0,
-            units=self.base_currency,
+        self.working_capital = pyo.Expression(
+            expr=self.working_capital_percent_FCI * self.aggregate_capital_cost,
             doc="Working capital - based on aggregate capital costs",
         )
-
-        self.land_cost_constraint = pyo.Constraint(
-            expr=self.land_cost
-            == self.aggregate_capital_cost * self.land_cost_percent_FCI
-        )
-        self.working_capital_constraint = pyo.Constraint(
-            expr=self.working_capital
-            == self.aggregate_capital_cost * self.working_capital_percent_FCI
-        )
         self.total_capital_cost_constraint = pyo.Constraint(
             expr=self.total_capital_cost
-            == self.aggregate_capital_cost + self.land_cost + self.working_capital
+            == self.factor_total_investment * self.aggregate_capital_cost
         )
 
         # Other fixed costs
-        self.salary_cost = pyo.Var(
-            initialize=0,
-            units=self.base_currency / self.base_period,
+        self.salary_cost = pyo.Expression(
+            expr=self.salaries_percent_FCI * self.aggregate_capital_cost,
             doc="Salary costs - based on aggregate capital costs",
         )
-        self.benefits_cost = pyo.Var(
-            initialize=0,
-            units=self.base_currency / self.base_period,
+        self.benefits_cost = pyo.Expression(
+            expr=self.benefit_percent_of_salary
+            * self.salaries_percent_FCI
+            * self.aggregate_capital_cost,
             doc="Benefits costs - based on percentage of salary costs",
         )
-        self.maintenance_cost = pyo.Var(
-            initialize=0,
-            units=self.base_currency / self.base_period,
+        self.maintenance_cost = pyo.Expression(
+            expr=self.maintenance_costs_percent_FCI * self.aggregate_capital_cost,
             doc="Maintenance costs - based on aggregate capital costs",
         )
-        self.laboratory_cost = pyo.Var(
-            initialize=0,
-            units=self.base_currency / self.base_period,
+        self.laboratory_cost = pyo.Expression(
+            expr=self.laboratory_fees_percent_FCI * self.aggregate_capital_cost,
             doc="Laboratory costs - based on aggregate capital costs",
         )
-        self.insurance_and_taxes_cost = pyo.Var(
-            initialize=0,
-            units=self.base_currency / self.base_period,
+        self.insurance_and_taxes_cost = pyo.Expression(
+            expr=self.insurance_and_taxes_percent_FCI * self.aggregate_capital_cost,
             doc="Insurance and taxes costs - based on aggregate capital costs",
         )
-        self.total_fixed_operating_cost = pyo.Var(
-            initialize=0,
-            units=self.base_currency / self.base_period,
-            doc="Total fixed operating costs",
+        self.factor_maintenance_labor_chemical = pyo.Expression(
+            expr=self.salaries_percent_FCI
+            + self.benefit_percent_of_salary * self.salaries_percent_FCI
+            + self.maintenance_costs_percent_FCI
+            + self.laboratory_fees_percent_FCI
+            + self.insurance_and_taxes_percent_FCI,
+            doc="Maintenance-labor-chemical factor [fraction of equipment cost/year]",
         )
 
-        self.salary_cost_constraint = pyo.Constraint(
-            expr=self.salary_cost
-            == self.aggregate_capital_cost * self.salaries_percent_FCI
-        )
-        self.benefits_cost_constraint = pyo.Constraint(
-            expr=self.benefits_cost == self.salary_cost * self.benefit_percent_of_salary
-        )
-        self.maintenance_cost_constraint = pyo.Constraint(
-            expr=self.maintenance_cost
-            == self.aggregate_capital_cost * self.maintenance_costs_percent_FCI
-        )
-        self.laboratory_cost_constraint = pyo.Constraint(
-            expr=self.laboratory_cost
-            == self.aggregate_capital_cost * self.laboratory_fees_percent_FCI
-        )
-        self.insurance_and_taxes_cost_constraint = pyo.Constraint(
-            expr=self.insurance_and_taxes_cost
-            == self.aggregate_capital_cost * self.insurance_and_taxes_percent_FCI
+        self.maintenance_labor_chemical_operating_cost = pyo.Expression(
+            expr=self.factor_maintenance_labor_chemical * self.aggregate_capital_cost,
+            doc="Maintenance-labor-chemical operating cost",
         )
 
-        self.total_fixed_operating_cost_constraint = pyo.Constraint(
-            expr=self.total_fixed_operating_cost
-            == self.aggregate_fixed_operating_cost
-            + self.salary_cost
-            + self.benefits_cost
-            + self.maintenance_cost
-            + self.laboratory_cost
-            + self.insurance_and_taxes_cost
+        self.total_fixed_operating_cost = pyo.Expression(
+            expr=self.aggregate_fixed_operating_cost
+            + self.maintenance_labor_chemical_operating_cost,
+            doc="Total fixed operating costs",
         )
 
         # Other variable costs
         self.total_variable_operating_cost = pyo.Expression(
-            expr=self.aggregate_variable_operating_cost
-            + sum(self.aggregate_flow_costs[f] for f in self.used_flows)
-            * self.utilization_factor,
+            expr=(
+                self.aggregate_variable_operating_cost
+                + sum(self.aggregate_flow_costs[f] for f in self.used_flows)
+                * self.utilization_factor
+            )
+            if self.used_flows
+            else self.aggregate_variable_operating_cost,
             doc="Total variable operating cost of process per operating period",
         )
 
@@ -253,32 +232,11 @@ def initialize_build(self):
         """
         Basic initialization for flowsheet level quantities
         """
-        calculate_variable_from_constraint(self.land_cost, self.land_cost_constraint)
-        calculate_variable_from_constraint(
-            self.working_capital, self.working_capital_constraint
-        )
         calculate_variable_from_constraint(
             self.total_capital_cost, self.total_capital_cost_constraint
         )
-
-        calculate_variable_from_constraint(
-            self.salary_cost, self.salary_cost_constraint
-        )
-        calculate_variable_from_constraint(
-            self.benefits_cost, self.benefits_cost_constraint
-        )
-        calculate_variable_from_constraint(
-            self.maintenance_cost, self.maintenance_cost_constraint
-        )
-        calculate_variable_from_constraint(
-            self.laboratory_cost, self.laboratory_cost_constraint
-        )
-        calculate_variable_from_constraint(
-            self.insurance_and_taxes_cost, self.insurance_and_taxes_cost_constraint
-        )
-
         calculate_variable_from_constraint(
-            self.total_fixed_operating_cost, self.total_fixed_operating_cost_constraint
+            self.total_operating_cost, self.total_operating_cost_constraint
         )
 
 

watertap/examples/flowsheets/RO_with_energy_recovery/tests/test_RO_with_energy_recovery_simulation.py

@@ -110,7 +110,6 @@ def test_build(self, system_frame):
 
         var_str_list = [
             "total_capital_cost",
-            "maintenance_labor_chemical_operating_cost",
             "total_operating_cost",
         ]
         for var_str in var_str_list:

watertap/examples/flowsheets/electrodialysis/tests/test_electrodialysis_1stack.py

@@ -77,7 +77,6 @@ def test_build_model(self, electrodialysis_1D1stack):
 
         var_str_list = [
             "total_capital_cost",
-            "maintenance_labor_chemical_operating_cost",
             "total_operating_cost",
         ]
         for var_str in var_str_list:

watertap/examples/flowsheets/ion_exchange/tests/test_ion_exchange_demo.py

@@ -80,7 +80,6 @@ def test_build_model(self, ix_0D):
 
         var_str_list = [
             "total_capital_cost",
-            "maintenance_labor_chemical_operating_cost",
             "total_operating_cost",
         ]
         for var_str in var_str_list:

watertap/examples/flowsheets/lsrro/lsrro.py

@@ -420,6 +420,7 @@ def stage_recovery_mass_H2O(fs, stage):
         * (
             1
             + m.fs.costing.factor_maintenance_labor_chemical
+            / m.fs.costing.factor_total_investment
             / m.fs.costing.factor_capital_annualization
         )
         + m.fs.costing.electricity_lcow
@@ -454,6 +455,7 @@ def stage_recovery_mass_H2O(fs, stage):
         * (
             1
             + m.fs.costing.factor_maintenance_labor_chemical
+            / m.fs.costing.factor_total_investment
             / m.fs.costing.factor_capital_annualization
         )
         + m.fs.costing.membrane_replacement_lcow

watertap/examples/flowsheets/mvc/mvc_single_stage.py

@@ -619,7 +619,6 @@ def scale_costs(m):
     calculate_cost_sf(m.fs.costing.aggregate_capital_cost)
     calculate_cost_sf(m.fs.costing.aggregate_flow_costs["electricity"])
     calculate_cost_sf(m.fs.costing.total_capital_cost)
-    calculate_cost_sf(m.fs.costing.maintenance_labor_chemical_operating_cost)
     calculate_cost_sf(m.fs.costing.total_operating_cost)
 
     iscale.calculate_scaling_factors(m)

watertap/examples/flowsheets/mvc/tests/test_mvc_single_stage.py

@@ -109,7 +109,6 @@ def test_build_model(self, mvc_single_stage):
 
         var_str_list = [
             "total_capital_cost",
-            "maintenance_labor_chemical_operating_cost",
             "total_operating_cost",
         ]
         for var_str in var_str_list:

watertap/examples/flowsheets/nf_dspmde/nf_ui.py

@@ -235,7 +235,7 @@ def export_variables(flowsheet=None, exports=None, build_options=None, **kwargs)
         obj=fs.costing.factor_maintenance_labor_chemical,
         name="Maintenance-labor-chemical factor",
         ui_units=pyunits.year**-1,
-        display_units="fraction of investment cost/year",
+        display_units="fraction of equipment cost/year",
         rounding=4,
         description="NF OPEX",
         is_input=True,