Even though the rebels coped with their challenges in terms of financial reserves, using perpetuating energy sources such as the Ultragenerator would greatly eliminate the need for Diesel to power up the prison facility. Therefore, eliminating unnecessary costs.
As Leric told Lance during the attack in the tunnels, the SHF group found remnants of food and clothing left as the rebels fled. Thus, the rebels were still recuperating with clothing and food supplies which entails the utmost financial need for such provisions.
"Going back to the mystery woman. Is she gonna meet you again?" Damian asked.
"I don't know. She said they were spying on me. She said she would help me. But they need me to build a stronger Ultragenerator. If it happens, she will show me the Lost Engineers," Lance said.