Variable pressure turbine

A power generation system comprising:

• at least two turbomachinery systems, wherein at least one of the at least two turbomachinery systems is operable as a compressor system and at least one of the at least two turbomachinery systems is operable as a turbine system;
• a closed cycle system configured to generate power, the closed cycle system comprising a working fluid circulating in a closed cycle path through, in sequence, the compressor system, a hot side heat exchanger, the turbine system, and a cold side heat exchanger, wherein the closed cycle path comprises a high pressure leg and a low pressure leg;
• a combustor disposed external to the closed cycle path and without being in fluid communication with at least the cold side heat exchanger, wherein the combustor provides thermal energy to the working fluid exiting the compressor system via the hot side heat exchanger;
• and
• a computer system configured to:
• determine to adjust an amount of power generated by the closed cycle system,
• and in response to the determination to adjust the amount of power generated by the closed cycle system, cause an adjustment in a pressure of the working fluid in the closed cycle path.