I still don’t follow.

If the geothermal plant isn’t ran at or near capacity all the time, the capex takes longer to recoup.

You can’t just, say, run it at 50% for a while, and then at 150% later, because a) ya typically can’t run plant at 150%, and for power generators ya can only run them at whatever you’re contracted to supply, so you’d typically want to run geothermal at capacity all the time.

This is true of anything that requires capital expenditure.