Add documentation for multi fuels

1. add the description of new variables in data_documentation.md

docs/src/data_documentation.md

@@ -313,6 +313,10 @@ This file contains cost and performance parameters for various generators and ot
 |VRE_STOR | {0, 1}, Flag to indicate membership in set of co-located variable renewable energy resources (onshore wind and utility-scale solar PV) and storage resources (either short- or long-duration energy storage with symmetric or asymmetric charging or discharging capabilities).|
 ||VRE_STOR = 0: Not part of set (default) |
 ||VRE_STOR = 1: Co-located VRE and storage (VRE-STOR) resources. |
+|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) |
+||VMULTI_FUELS = 1: Resources that can use fuel blending. |
+
 |**Existing technology capacity**|
 |Existing\_Cap\_MW |The existing capacity of a power plant in MW. Note that for co-located VRE-STOR resources, this capacity represents the existing AC grid connection capacity in MW. |
 |Existing\_Cap\_MWh |The existing capacity of storage in MWh where `STOR = 1` or `STOR = 2`. Note that for co-located VRE-STOR resources, this capacity represents the existing capacity of storage in MWh. |
@@ -336,6 +340,19 @@ This file contains cost and performance parameters for various generators and ot
 |**Technical performance parameters**|
 |Heat\_Rate\_MMBTU\_per\_MWh  |Heat rate of a generator or MMBtu of fuel consumed per MWh of electricity generated for export (net of on-site consumption). The heat rate is the inverse of the efficiency: a lower heat rate is better. Should be consistent with fuel prices in terms of reporting on higher heating value (HHV) or lower heating value (LHV) basis. |
 |Fuel  |Fuel needed for a generator. The names should match with the ones in the `Fuels_data.csv`. |
+|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. |
 |Self\_Disch  |[0,1], The power loss of storage technologies per hour (fraction loss per hour)- only applies to storage techs. Note that for co-located VRE-STOR resources, this value applies to the storage component of each resource.|
 |Min\_Power |[0,1], The minimum generation level for a unit as a fraction of total capacity. This value cannot be higher than the smallest time-dependent CF value for a resource in `Generators_variability.csv`. Applies to thermal plants, and reservoir hydro resource (`HYDRO = 1`).|
 |Ramp\_Up\_Percentage |[0,1], Maximum increase in power output from between two periods (typically hours), reported as a fraction of nameplate capacity. Applies to thermal plants, and reservoir hydro resource (`HYDRO = 1`).|