Open two respected sources on the same LNG project and the capacity figures rarely match exactly. This is not usually because one source made an error. It is because “capacity” is being asked to answer several different questions at once, and the two sources answered different ones.
Cause one: units and conversion
Mtpa, bcm/y, cubic metres and MMBtu measure different physical quantities, and converting between them requires an assumed gas composition. This site uses 1 Mtpa equals 1.36 bcm/y throughout; another compiler using 1.38 will produce a figure roughly one and a half per cent different for no reason beyond the conversion factor, and neither is incorrect. The gap widens further wherever a source silently mixes design output with delivered energy, which are not even the same kind of quantity.
Cause two: which statuses are included
The single largest source of large, headline-grabbing discrepancies. A total describing “capacity” might mean operating only, operating plus construction, or every status including speculative proposals — and adding those categories together produces a number that describes no possible world. Two sources with identical underlying data but different status inclusion rules can differ by a factor of two or three, and the difference has nothing to do with data quality.
Cause three: nameplate against actual
A design specification and a measured output are different quantities that happen to share units. Nameplate capacity is what a plant was built to produce under reference conditions; actual output varies with weather, feedstock and maintenance, sometimes above nameplate and sometimes below. A source quoting one year’s actual production and a source quoting the design figure will disagree even when both are drawn from the same facility and neither has made an error.
Cause four: which primary source was used, and when
Every tracker is a compilation. Official filings, company announcements, government permits and industry press each report a project at a point in time, and they do not always agree with each other even at the primary-source level — a permit application might state a different design capacity than the plant’s later commissioning documents, both being accurate answers to slightly different questions asked at different stages.
A compiler resolving several such sources makes a judgement about which to prefer, typically the most recent and most specific. Two compilers applying broadly similar rules can still land on different primary sources if their update cycles do not align, particularly for a project whose status is changing quickly. This is invisible in the finished number: a reader sees only the figure, not the primary-source decision behind it.
What updates between releases, and why that is not the same as an error
A tracker revising a figure between releases usually reflects one of two entirely different things, and the distinction matters. The underlying reality changed — a debottlenecking raised real output, a permit amendment changed design capacity, a status moved from proposed to under construction. Or the compiler found a better primary source for a figure that was always approximate, with nothing in the world having changed at all.
The change log on this site records exactly this kind of revision as a comparison between two dated releases, without asserting which of the two explanations applies — that judgement is usually not recoverable from the data alone, and stating it anyway would be exactly the kind of confidence the underlying sources do not support.
What to actually do about it
Check units first — is it Mtpa, bcm/y, or something else, and was a conversion applied. Check status coverage second — does the figure state which statuses are included, and if it does not, treat it as unusable for comparison. Check whether it is a design or a measured figure third. And prefer a source that discloses its methodology over one that states a number with no stated basis, because an explicit assumption can be checked and an implicit one cannot.
None of this means most capacity figures are wrong. It means “capacity” is shorthand for several different quantities, and reading it correctly requires knowing which one a given figure is answering.