Thermal energy storage - Johnson Controls - LIT-12013036 - OpenBlue Central Utility Plant - OpenBlue Central Utility Plant - v2023.Q3

OpenBlue Plant Optimizer Administration and User Guide

Johnson Controls
Product name
OpenBlue Central Utility Plant
Document type
Administration Guide
User Guide
Document number
Revision date

In Solver Parameters, admin users can configure new solver parameters for Thermal Energy Storage (TES) including Backup Mode Select, Saving Threshold, and Tank Bias.

The Backup Mode Select determines if the optimization keeps the TES fully charged for emergency backup purposes when it is not in use.

Table 1. Backup Mode Select parameters
Backup Mode Select mode name Description
None No change from normal thermal energy storage tank behavior.

Maintain a charge level at the storage’s maximum state of charge for emergency backup purposes.


Discharge the storage (used to refresh thermocline in typical thermal energy storage).


Define a savings threshold $ per unit energy ($/ton-hour or $/kWh). When the potential cost saving is greater than or equal to the savings threshold value, the tank discharges. Otherwise, when the potential saving is less than this value, the tank maintains the charge level for emergency backup purposes.

The Tank Bias solver parameter ($/kWh) is the value that is added to the optimization function at the end of each step of the horizon, where there is energy left in the thermal energy storage tank. The Tank Bias is used to bias the tank to have a fuller charge. The Tank Bias should typically take on a value very near zero, as it has units in $/kWh. You can use the Tank Bias parameter when TES Backup Mode Select mode is not being used, but in most cases the Backup Mode Select is the preferred solution.