Enable thermal power plants to burn multiple fuels (#586)

This feature enables thermal generators to burn multiple fuels at the same time and also allows the user to specify the co-firing level during both startup and generation processes to meet potential regulations (e.g., H2 blending requirements in combustion turbines proposed by EPA). This feature also allows users to specify heat rates for different fuels in case there is any efficiency penalty due to co-firing.

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   piecewise-linear approximation of heat rate curves. 
   Adds a CO2 module that determines the CO2 emissions based on fuel consumption, CO2 capture 
   fraction, and whether the feedstock is biomass.
+- Enable thermal power plants to burn multiple fuels (#586) 
 - Feature electrolysis basic (#525)
   Adds hydrogen electrolyzer model which enables the addition of hydrogen electrolyzer
   demands along with optional clean supply constraints.
@@ -81,7 +82,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - The matrix-style input of the grid for Network.csv is deprecated in favor a column-style input.
   Instead of columns z1, z2, ... with entries -1, 0, 1, use two columns: Start_Zone, End_Zone (#591).
 
-
 ## [0.3.6] - 2023-08-01
 
 ### Fixed

Example_Systems/SmallNewEngland/OneZone_MultiFuels/CO2_cap.csv

@@ -0,0 +1,2 @@
+,Network_zones,CO_2_Cap_Zone_1,CO_2_Max_tons_MWh_1,CO_2_Max_Mtons_1
+NE,z1,1,0.05,0.018

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Capacity_reserve_margin.csv

@@ -0,0 +1,2 @@
+,Network_zones,CapRes_1
+NE,z1,0.156

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Demand_data.csv

@@ -0,0 +1,25 @@
+Voll,Demand_Segment,Cost_of_Demand_Curtailment_per_MW,Max_Demand_Curtailment,Rep_Periods,Timesteps_per_Rep_Period,Sub_Weights,Time_Index,Demand_MW_z1
+50000,1,1,1,1,24,8760,1,11162
+,,,,,,,2,10556
+,,,,,,,3,10105
+,,,,,,,4,9878
+,,,,,,,5,9843
+,,,,,,,6,10017
+,,,,,,,7,10390
+,,,,,,,8,10727
+,,,,,,,9,11298
+,,,,,,,10,11859
+,,,,,,,11,12196
+,,,,,,,12,12321
+,,,,,,,13,12381
+,,,,,,,14,12270
+,,,,,,,15,12149
+,,,,,,,16,12219
+,,,,,,,17,13410
+,,,,,,,18,14539
+,,,,,,,19,14454
+,,,,,,,20,14012
+,,,,,,,21,13494
+,,,,,,,22,12772
+,,,,,,,23,11877
+,,,,,,,24,10874

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Energy_share_requirement.csv

@@ -0,0 +1,2 @@
+,Network_zones,ESR_1,ESR_2
+NE,z1,0.259,0.348

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Fuels_data.csv

@@ -0,0 +1,26 @@
+Time_Index,NG,None,H2
+0,0.05306,0,0
+1,5.28,0,5
+2,5.28,0,5
+3,5.28,0,5
+4,5.28,0,5
+5,5.28,0,5
+6,5.28,0,5
+7,5.28,0,5
+8,5.28,0,5
+9,5.28,0,5
+10,5.28,0,5
+11,5.28,0,5
+12,5.28,0,5
+13,5.28,0,5
+14,5.28,0,5
+15,5.28,0,5
+16,5.28,0,5
+17,5.28,0,5
+18,5.28,0,5
+19,5.28,0,5
+20,5.28,0,5
+21,5.28,0,5
+22,5.28,0,5
+23,5.28,0,5
+24,5.28,0,5

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Generators_variability.csv

@@ -0,0 +1,25 @@
+Time_Index,natural_gas_combined_cycle,solar_pv,onshore_wind,battery
+1,1,0,0.889717042,1
+2,1,0,0.877715468,1
+3,1,0,0.903424203,1
+4,1,0,0.895153165,1
+5,1,0,0.757258117,1
+6,1,0,0.630928695,1
+7,1,0,0.557177782,1
+8,1,0,0.6072492,1
+9,1,0.1779,0.423417866,1
+10,1,0.429,0.007470775,1
+11,1,0.5748,0.002535942,1
+12,1,0.6484,0.002153709,1
+13,1,0.6208,0.00445132,1
+14,1,0.596,0.007711587,1
+15,1,0.5013,0.100848213,1
+16,1,0.3311,0.201802149,1
+17,1,0.0642,0.141933054,1
+18,1,0,0.567022562,1
+19,1,0,0.946024895,1
+20,1,0,0.923394203,1
+21,1,0,0.953386247,1
+22,1,0,0.929205418,1
+23,1,0,0.849528909,1
+24,1,0,0.665570974,1

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Maximum_capacity_requirement.csv

@@ -0,0 +1,4 @@
+MaxCapReqConstraint,ConstraintDescription,Max_MW
+1,PV,50000
+2,Wind,100000
+3,Batteries,60000

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Minimum_capacity_requirement.csv

@@ -0,0 +1,4 @@
+MinCapReqConstraint,ConstraintDescription,Min_MW
+1,PV,5000
+2,Wind,10000
+3,Batteries,6000

Example_Systems/SmallNewEngland/OneZone_MultiFuels/README.md

@@ -0,0 +1,15 @@
+# Small New England: One Zone with resources that can use multiple fuels
+
+**SmallNewEngland** is set of a simplified versions of the more detailed example system RealSystemExample. It is condensed for easy comprehension and quick testing of different components of the GenX. **SmallNewEngland/OneZone_MultiFules** is one of our most basic models, a 24-hour example with hourly resolution containing only one zone representing New England. The model includes only natural gas (cofiring with H2), solar PV, wind, and lithium-ion battery storage with no initial capacity. 
+
+To run the model, first navigate to the example directory at `GenX/Example_Systems/SmallNewEngland/OneZone_MultiFuels`:
+
+`cd("Example_Systems/SmallNewEngland/OneZone_MultiFuels")`
+
+Next, ensure that your settings in `GenX_settings.yml` are correct. The default settings use the solver HiGHS (`Solver: HiGHS`). Other optional policies include minimum capacity requirements, a capacity reserve margin, and more. 
+
+Once the settings are confirmed, run the model with the `Run.jl` script in the example directory:
+
+`include("Run.jl")`
+
+Once the model has completed, results will write to the `Results` directory.

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Reserves.csv

@@ -0,0 +1,2 @@
+Reg_Req_Percent_Demand,Reg_Req_Percent_VRE,Rsv_Req_Percent_Demand,Rsv_Req_Percent_VRE,Unmet_Rsv_Penalty_Dollar_per_MW,Dynamic_Contingency,Static_Contingency_MW
+0.01,0.0032,0.033,0.0795,1000,0,0

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Resources/Resource_capacity_reserve_margin.csv

@@ -0,0 +1,5 @@
+Resource,Derating_Factor_1
+natural_gas_combined_cycle,0.93
+solar_pv,0.8
+onshore_wind,0.8
+battery,0.95

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Resources/Resource_energy_share_requirement.csv

@@ -0,0 +1,3 @@
+Resource,ESR_1,ESR_2
+solar_pv,1,1
+onshore_wind,1,1

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Resources/Resource_maximum_capacity_requirement.csv

@@ -0,0 +1,4 @@
+Resource,Min_Cap_1,Min_Cap_2,Min_Cap_3
+solar_pv,1,0,0
+onshore_wind,0,1,0
+battery,0,0,1

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Resources/Resource_minimum_capacity_requirement.csv

@@ -0,0 +1,4 @@
+Resource,Min_Cap_1,Min_Cap_2,Min_Cap_3
+solar_pv,1,0,0
+onshore_wind,0,1,0
+battery,0,0,1

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Resources/storage.csv

@@ -0,0 +1,2 @@
+Resource,Zone,Model,New_Build,Min_Cap_MW,Min_Cap_MWh,Inv_Cost_per_MWyr,Inv_Cost_per_MWhyr,Fixed_OM_Cost_per_MWyr,Fixed_OM_Cost_per_MWhyr,Var_OM_Cost_per_MWh,Var_OM_Cost_per_MWh_In,Self_Disch,Eff_Up,Eff_Down,Min_Duration,Max_Duration,region,cluster,existing_cap_mw,existing_cap_mwh
+battery,1,1,1,0,0,19584,22494,4895,5622,0.15,0.15,0,0.92,0.92,1,10,NE,0,0,0

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Resources/thermal.csv

@@ -0,0 +1,2 @@
+Resource,Zone,Model,MULTI_FUELS,New_Build,Min_Cap_MW,Min_Cap_MWh,Min_Charge_Cap_MW,Inv_Cost_per_MWyr,Fixed_OM_Cost_per_MWyr,Var_OM_Cost_per_MWh,Heat_Rate_MMBTU_per_MWh,Fuel,Cap_Size,Start_Cost_per_MW,Start_Fuel_MMBTU_per_MW,Up_Time,Down_Time,Ramp_Up_Percentage,Ramp_Dn_Percentage,Hydro_Energy_to_Power_Ratio,Min_Power,Reg_Max,Rsv_Max,MGA,Resource_Type,region,cluster,Num_Fuels,Fuel1,Heat_Rate1_MMBTU_per_MWh,Fuel1_Min_Cofire_Level,Fuel1_Max_Cofire_Level,Fuel1_Min_Cofire_Level_Start,Fuel1_Max_Cofire_Level_Start,Fuel2,Heat_Rate2_MMBTU_per_MWh,Fuel2_Min_Cofire_Level,Fuel2_Max_Cofire_Level,Fuel2_Min_Cofire_Level_Start,Fuel2_Max_Cofire_Level_Start,Existing_cap_mw
+natural_gas_combined_cycle,1,1,1,1,0,0,0,65400,10287,3.55,7.43,NG,250,91,2,6,6,0.64,0.64,0,0.468,0.25,0.5,1,natural_gas_fired_combined_cycle,NE,1,2,NG,7.43,0.5,1,0,1,H2,7.43,0.5,1,0.05,1,0

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Resources/vre.csv

@@ -0,0 +1,3 @@
+Resource,Zone,Num_VRE_Bins,New_Build,Can_Retire,Min_Cap_MW,Min_Cap_MWh,Min_Charge_Cap_MW,Inv_Cost_per_MWyr,Fixed_OM_Cost_per_MWyr,Var_OM_Cost_per_MWh,Heat_Rate_MMBTU_per_MWh,MGA,Resource_Type,region,cluster,existing_cap_mw
+solar_pv,1,1,1,0,0,0,0,85300,18760,0,9.13,1,solar_photovoltaic,NE,1,0
+onshore_wind,1,1,1,0,0,0,0,97200,43205,0.1,9.12,1,onshore_wind_turbine,NE,1,0

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Run.jl

@@ -0,0 +1,3 @@
+using GenX
+
+run_genx_case!(dirname(@__FILE__))

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Settings/cplex_settings.yml

@@ -0,0 +1,10 @@
+# CPLEX Solver Parameters
+Feasib_Tol: 1.0e-05 # Constraint (primal) feasibility tolerances.
+Optimal_Tol: 1e-5 # Dual feasibility tolerances.
+Pre_Solve: 1 # Controls presolve level.
+TimeLimit: 110000 # Limits total time solver.
+MIPGap: 1e-3 # Relative (p.u. of optimal) mixed integer optimality tolerance for MIP problems (ignored otherwise).
+Method: 2 # Algorithm used to solve continuous models (including MIP root relaxation).
+BarConvTol: 1.0e-08 # Barrier convergence tolerance (determines when barrier terminates).
+NumericFocus: 0 # Numerical precision emphasis.
+SolutionType: 2 # Solution type for LP or QP.

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Settings/genx_settings.yml

@@ -0,0 +1,20 @@
+OverwriteResults: 0 # Overwrite existing results in output folder or create a new one; 0 = create new folder; 1 = overwrite existing results
+PrintModel: 0 # Write the model formulation as an output; 0 = active; 1 = not active
+NetworkExpansion: 0 # Transmission network expansionl; 0 = not active; 1 = active systemwide
+Trans_Loss_Segments: 1 # Number of segments used in piecewise linear approximation of transmission losses; 1 = linear, >2 = piecewise quadratic
+Reserves: 0 # Regulation (primary) and operating (secondary) reserves; 0 = not active, 1 = active systemwide
+EnergyShareRequirement: 1 # Minimum qualifying renewables penetration; 0 = not active; 1 = active systemwide
+CapacityReserveMargin: 1 # Number of capacity reserve margin constraints; 0 = not active; 1 = active systemwide
+CO2Cap: 0 # CO2 emissions cap; 0 = not active (no CO2 emission limit); 1 = mass-based emission limit constraint; 2 = demand + rate-based emission limit constraint; 3 = generation + rate-based emission limit constraint
+StorageLosses: 1 # Energy Share Requirement and CO2 constraints account for energy lost; 0 = not active (DO NOT account for energy lost); 1 = active systemwide (DO account for energy lost)
+MinCapReq: 1  # Activate minimum technology carveout constraints; 0 = not active; 1 = active
+MaxCapReq: 1  # Activate maximum technology carveout constraints; 0 = not active; 1 = active
+ParameterScale: 1 # Turn on parameter scaling wherein load, capacity and power variables are defined in GW rather than MW. 0 = not active; 1 = active systemwide
+WriteShadowPrices: 1 # Write shadow prices of LP or relaxed MILP; 0 = not active; 1 = active
+UCommit: 2 # Unit committment of thermal power plants; 0 = not active; 1 = active using integer clestering; 2 = active using linearized clustering
+TimeDomainReductionFolder: "TDR_Results" # Directory name where results from time domain reduction will be saved. If results already exist here, these will be used without running time domain reduction script again.
+TimeDomainReduction: 0 # Time domain reduce (i.e. cluster) inputs based on Demand_data.csv, Generators_variability.csv, and Fuels_data.csv; 0 = not active (use input data as provided); 0 = active (cluster input data, or use data that has already been clustered)
+ModelingToGenerateAlternatives: 0 # Modeling to generate alternatives; 0 = not active; 1 = active. Note: produces a single solution as output
+ModelingtoGenerateAlternativeSlack: 0.1 # Slack value as a fraction of least-cost objective in budget constraint used for evaluating alternative model solutions; positive float value
+ModelingToGenerateAlternativeIterations: 3 # Number of MGA iterations with maximization and minimization objective
+MethodofMorris: 0 #Flag for turning on the Method of Morris analysis

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Settings/gurobi_settings.yml

@@ -0,0 +1,15 @@
+# Gurobi Solver Parameters
+# Common solver settings
+Feasib_Tol: 1.0e-05           # Constraint (primal) feasibility tolerances.
+Optimal_Tol: 1e-5             # Dual feasibility tolerances.
+TimeLimit: 110000             # Limits total time solver.
+Pre_Solve: 1                  # Controls presolve level.
+Method: 2                  # Algorithm used to solve continuous models (including MIP root relaxation).
+
+#Gurobi-specific solver settings
+MIPGap: 1e-3                  # Relative (p.u. of optimal) mixed integer optimality tolerance for MIP problems (ignored otherwise).
+BarConvTol: 1.0e-08           # Barrier convergence tolerance (determines when barrier terminates).
+NumericFocus: 0               # Numerical precision emphasis.
+Crossover: 0                # Barrier crossver strategy.
+PreDual: 0                    # Decides whether presolve should pass the primal or dual linear programming problem to the LP optimization algorithm.
+AggFill: 10                   # Allowed fill during presolve aggregation.

Example_Systems/SmallNewEngland/OneZone_MultiFuels/Settings/highs_settings.yml

@@ -0,0 +1,13 @@
+# HiGHS Solver Parameters
+# Common solver settings
+Feasib_Tol: 1.0e-05        # Primal feasibility tolerance # [type: double, advanced: false, range: [1e-10, inf], default: 1e-07]
+Optimal_Tol: 1.0e-05       # Dual feasibility tolerance # [type: double, advanced: false, range: [1e-10, inf], default: 1e-07]
+TimeLimit: 1.0e23             # Time limit # [type: double, advanced: false, range: [0, inf], default: inf]
+Pre_Solve: choose          # Presolve option: "off", "choose" or "on" # [type: string, advanced: false, default: "choose"]
+Method: choose             #HiGHS-specific solver settings # Solver option: "simplex", "choose" or "ipm" # [type: string, advanced: false, default: "choose"]
+
+#highs-specific solver settings
+
+# run the crossover routine for ipx
+# [type: string, advanced: "on", range: {"off", "on"}, default: "off"]
+run_crossover: "on"

docs/src/data_documentation.md

@@ -934,6 +934,32 @@ This file contains the time-series of capacity factors / availability of the win
 
 • Second column onwards: Resources are listed from the second column onward with headers matching each resource name in the `Vre_stor.csv` files in any order. The availability for each resource at each time step is defined as a fraction of installed capacity and should be between 0 and 1. Note that for this reason, resource names specified in all the resource `.csv` files must be unique. 
 
+#### 2.2.12 Settings-specific columns in the Generators\_data.csv to use multi fuels
+
+This file contains additional setting and performance parameters for specifically thermal resources that use multiple fuels.
+These variables must be explicitly listed in the `Generators_data.csv`.
+
+###### Table 17: Settings-specific columns in the Generators\_data.csv file to use multi fuels
+|**Column Name** | **Description**|
+| :------------ | :-----------|
+|**Technology type flags**|
+|MULTI_FUELS | {0, 1}, Flag to indicate membership in set of thermal resources that can burn multiple fuels at the same time (e.g., natural gas combined cycle cofiring with hydrogen, coal power plant cofiring with natural gas.|
+||MULTI_FUELS = 0: Not part of set (default) |
+||MULTI_FUELS = 1: Resources that can use fuel blending. |
+|**Technical performance parameters**|
+|Num\_Fuels  |Number of fuels that a multi-fuel generator (MULTI_FUELS = 1) can use at the same time. The length of ['Fuel1', 'Fuel2', ...] should be equal to 'Num\_Fuels'. Each fuel will requires its corresponding heat rate, min cofire level, and max cofire level. |
+|Fuel1  |Frist fuel needed for a mulit-fuel generator (MULTI_FUELS = 1). The names should match with the ones in the `Fuels_data.csv`. |
+|Fuel2  |Second fuel needed for a mulit-fuel generator (MULTI_FUELS = 1). The names should match with the ones in the `Fuels_data.csv`. |
+|Heat1\_Rate\_MMBTU\_per\_MWh  |Heat rate of a multi-fuel generator (MULTI_FUELS = 1) for Fuel1. |
+|Heat2\_Rate\_MMBTU\_per\_MWh  |Heat rate of a multi-fuel generator (MULTI_FUELS = 1) for Fuel2. |
+|Fuel1\_Min\_Cofire\_Level  |The minimum blendng level of 'Fuel1' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the normal generation process. |
+|Fuel1\_Min\_Cofire_Level\_Start  |The minimum blendng level of 'Fuel1' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the start-up process. |
+|Fuel1\_Max\_Cofire\_Level  |The maximum blendng level of 'Fuel1' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the normal generation process. |
+|Fuel1\_Max\_Cofire_Level\_Start  |The maximum blendng level of 'Fuel1' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the start-up process. |
+|Fuel2\_Min\_Cofire\_Level  |The minimum blendng level of 'Fuel2' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the normal generation process. |
+|Fuel2\_Min\_Cofire_Level\_Start  |The minimum blendng level of 'Fuel2' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the start-up process. |
+|Fuel2\_Max\_Cofire\_Level  |The maximum blendng level of 'Fuel2' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the normal generation process. |
+|Fuel2\_Max\_Cofire_Level\_Start  |The maximum blendng level of 'Fuel2' in total heat inputs of a mulit-fuel generator (MULTI_FUELS = 1) during the start-up process. |
 
 ## 3 Outputs
 

src/load_inputs/load_resources_data.jl

@@ -946,6 +946,17 @@ function add_resources_to_input_data!(inputs::Dict, setup::Dict, case_path::Abst
     # For now, the only resources eligible for UC are themal resources
     inputs["COMMIT"] = inputs["THERM_COMMIT"]
 
+	# Set of CCS resources (optional set):
+    inputs["CCS"] = ids_with_positive(gen, co2_capture_fraction)
+
+    # Single-fuel resources
+	inputs["SINGLE_FUEL"] = ids_with_singlefuel(gen)
+	# Multi-fuel resources
+	inputs["MULTI_FUELS"] = ids_with_multifuels(gen)
+	if !isempty(inputs["MULTI_FUELS"]) # If there are any resources using multi fuels, read relevant data
+		load_multi_fuels_data!(inputs, gen, setup, case_path)
+	end
+
     buildable = is_buildable(gen)
     retirable = is_retirable(gen)
 
@@ -1060,7 +1071,11 @@ function add_resources_to_input_data!(inputs::Dict, setup::Dict, case_path::Abst
 
     # Fuel
     inputs["HAS_FUEL"] = ids_with_fuel(gen)
-
+    if !isempty(inputs["MULTI_FUELS"])
+        inputs["HAS_FUEL"] = union(inputs["HAS_FUEL"], inputs["MULTI_FUELS"])
+        sort!(inputs["HAS_FUEL"])
+    end
+
     inputs["RESOURCES"] = gen
     return nothing
 end
@@ -1131,3 +1146,42 @@ function load_resources_data!(inputs::Dict, setup::Dict, case_path::AbstractStri
         return nothing
     end
 end
+
+@doc raw"""
+	load_multi_fuels_data!(inputs::Dict, setup::Dict, path::AbstractString)
+
+Function for reading input parameters related to multi fuels
+"""
+function load_multi_fuels_data!(inputs::Dict, gen::Vector{<:AbstractResource}, setup::Dict, path::AbstractString)
+
+	inputs["NUM_FUELS"] = num_fuels.(gen)   # Number of fuels that this resource can use
+	max_fuels = maximum(inputs["NUM_FUELS"])
+    inputs["FUEL_COLS"] = [ Symbol(string("Fuel",f)) for f in 1:max_fuels ]
+	fuel_types = [fuel_cols.(gen, tag=f) for f in 1:max_fuels]
+	heat_rates = [heat_rate_cols.(gen, tag=f) for f in 1:max_fuels]
+	max_cofire = [max_cofire_cols.(gen, tag=f) for f in 1:max_fuels]
+	min_cofire = [min_cofire_cols.(gen, tag=f) for f in 1:max_fuels]
+	max_cofire_start = [max_cofire_start_cols.(gen, tag=f) for f in 1:max_fuels]
+	min_cofire_start = [min_cofire_start_cols.(gen, tag=f) for f in 1:max_fuels]
+	inputs["HEAT_RATES"] = heat_rates
+	inputs["MAX_COFIRE"] = max_cofire
+	inputs["MIN_COFIRE"] = min_cofire
+	inputs["MAX_COFIRE_START"] = max_cofire_start
+	inputs["MIN_COFIRE_START"] = min_cofire_start
+	inputs["FUEL_TYPES"] = fuel_types
+	inputs["MAX_NUM_FUELS"] = max_fuels
+    inputs["MAX_NUM_FUELS"] = max_fuels
+
+	# check whether non-zero heat rates are used for resources that only use a single fuel
+	for f in 1:max_fuels
+		for hr in heat_rates[f][inputs["SINGLE_FUEL"]]
+			if  hr > 0 
+				error("Heat rates for multi fuels must be zero when only one fuel is used")
+			end
+		end
+	end
+	# do not allow the multi-fuel option when piece-wise heat rates are used
+    if haskey(inputs, "THERM_COMMIT_PWFU") && !isempty(inputs["THERM_COMMIT_PWFU"])
+		error("Multi-fuel option is not available when piece-wise heat rates are used. Please remove multi fuels to avoid this error.")
+	end
+end