Why waste-heat steam is poor for carrier catapults

Could gas-turbine waste heat supply steam catapults on the Queen Elizabeth class?

Not efficiently enough for sustained catapult operations; the required steam pressure, volume, and ship alterations make the idea impractical.

Waste-heat boilers can generate steam, but aircraft catapults require a dense, high-pressure supply delivered at an operationally useful rate. Retrofitting the necessary plant and piping would be so inefficient and invasive that a new ship becomes the more credible solution. The distinction is between recovering some steam in theory and repeatedly launching aircraft at carrier sortie rates. Existing gas-turbine machinery, boiler capacity, and piping were not designed around that concentrated demand.