The machines I've seen are essentially autoclaves, so sealed high pressure chambers. What you've expanded on is correct. The point I was trying to make was tha

The machines I've seen are essentially autoclaves, so sealed high pressure chambers. What you've expanded on is correct. The point I was trying to make was that at an industrial scale, the back of the envelope calculation you first presented isn't particularly useful in working out the energy delta between reusing vs recycling.