The core of this particular argument is the following:
> Think about it like this. We have 3 variables:
> 1. Inlet Gas Flow rate (measured by mmscf/d but easily convertible to pounds methane equiv.)
> 2. The VOC content mass % of the inlet stream
> 3. The Loss Rate through leaks in valves, fittings, etc. This is the fraction of the total inlet stream is lost to the air
> We simply multiply these three items together to get:
> 4. The VOC emission rate in tons per year (US short tons are EPA standard)
> Since we know #4 (The PEA told us), we know #2 (Pipeline Quality Gas is always <0.1% VOCs, and usually lower), and #3 is a range (with modern cryo plants at the lower end), we can simply go backwards to calculate implied flow rate
#1 is what this post is trying to calculate, to see what is or isn't reasonable.
#4 is the PEA: https://www.faa.gov/space/stakeholder_engagement/spacex_star...
And is basically the starting point of all calculations. Just Ctrl-F "45.8", the number that ESG_Hound uses in his excel-spreadsheet. That gets you to page 44, the number seems to check out. This post is trying to answer the question: when they wrote this PEA, what assumptions did the engineers make?
#3 is a reasonable assumption that doesn't change much.
The last variable is #2: which has two paths:
1. 99.9% pure pipeline methane -- When we plug in 99.9% pure methane into the calculations, the numbers are absurd. This is a "disproof by absurdity". So we know it can't be 99.9% methane from standard pipelines.
2. Maybe its "raw" methane from a well (varies from 3% to 10%). -- When plugging in these numbers, we calculate a 4.77% VOC rate, which suggests that all the calculations in the PEA were done __ASSUMING__ raw methane.
Now sure, our model isn't going to be the same model as whoever prepared this PEA. but we're probably going to be "within the same magnitude". Calculations, when done independently, will rhyme.
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It seems like a simple argument to me. What part of the discussion are people getting tripped up on?
When using 99.9% pure methane, the amount of Mega-scf of natural gas goes completely out of whack with any reasonable excel-sheet formula. As such, 99.9% pipeline methane cannot be the source of SpaceX's methane (at least, not with the assumptions listed in the PEA).
Does anyone have a problem with any of the assumed numbers? #1, #2, #3 or #4?
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So the QED is: SpaceX, when they wrote this PEA, assumed they'd be using raw, untreated natural gas straight from a well. Why would they make this assumption? Is SpaceX planning to set up a pre-treatment natural gas plant inside of Starbase?
