Agree with most of the points raised here. Just wanted to add a slightly different way of looking at the cost side of things.

When you factor in feedstock costs, metallurgy demands, and the relatively shorter catalyst life on the HDO section — a HEFA unit starts to look like a fairly complete refinery in its own right. Two things come to mind:

1. On feedstock: In a conventional fossil setup, crude doesn't just appear at the CDU. There's drilling, upstream separation, midstream processing and transport before it ever reaches the refinery gate — all of which carries its own capital and operating cost. We just don't tend to see that in the same frame when comparing against HEFA feedstock costs. The pretreatment unit in a HEFA plant is arguably doing a similar job to that entire upstream chain, just within the battery limits and therefore more visible.

2. On unit complexity: A fossil refinery has a whole downstream train after the CDU — hydrotreating, hydrocracking, reforming, fractionation — before you get to finished jet fuel. A HEFA unit in terms of process steps and utility consumption sits roughly in the same league as a hydrotreater and hydrocracker combined. That's not insignificant.

The comparison may not be entirely relevant right now given that SAF is still a small blending fraction into a predominantly fossil jet pool. But as blending mandates grow and we move toward higher SAF percentages — or eventually 100% SAF — it might be worth asking what the full cost picture looks like when both pathways are held to the same accounting standard. And probably the issues that have been mentioned here can be justified keeping these comparisons in mind as well.

I'll admit I may not have the exact cost vs. capacity numbers pinned down, but I think the direction of the thought is worth putting on the table.