CALC-062
NASA OTPS RD1 and RD2 rebuilt bottom-up at the common 20-year basis
What this is
This is the project's own arithmetic, published in full so it can be checked rather than taken on trust. It is not a source. Every input it uses is cited to a record, and the conclusion it reaches only carries as far as those inputs do.
Feeds CLM-0373. Answers QST-004. Basis: GBP2024/MWh, 20-year system life, 3 and 10 per cent real.
Script. restate-lcoe.py SECTION 4, section_nasa_rebuild() (line 286) with
rerun_at_life_and_rate() (line 268), which reuses the validated model from lcoe-model.py
declared at CALC-053 and CALC-054.
Why it was needed. This is the only study in the comparison for which a bottom-up model exists, so it is the only one that can be moved to a new asset life properly rather than approximated. Using the shortcut here when a rebuild was available would have imported the 9-29 per cent error measured in CALC-061 into the single most load-bearing figure in the exercise.
Inputs. All of CALC-053's and CALC-054's, plus:
| Quantity | Value | Source | Stated or assumed |
|---|---|---|---|
| Target system life | 20 yr | this restatement's chosen common basis | STATED as a choice |
| US CPI multiplier 2022 to 2024 | 1.0712 | CALC-060 | ASSUMED (recalled) |
| USD per GBP 2024 | 1.278 | CALC-060 | ASSUMED (recalled) |
| NASA Operate and Dispose cost lumps | $3.79bn / $24.7bn (RD1); $9.36bn / $38.9bn (RD2) | SRC-012 | STATED by the source at 30-year life, and carried over UNCHANGED to the 20-year rebuild, because no life-scaling function is stated. The claim names the direction of that choice itself: it makes the 20-year rebuild conservative, i.e. LCOE-inflating |
| RD2 figure used | the DCF rebuild at CALC-054, not NASA's published 1.59 USD/kWh | CALC-054, CALC-055 | STATED as a choice, with the reason: the rebuild does not carry the capacity-factor double-count of CALC-055 |
Working, transcribed.
RD1 rebuilt at 20 yr, 3 per cent 0.6729 USD/kWh (FY2022 USD)
x 1.0712 (US CPI to 2024) = 720.82 USD2024/MWh
/ 1.278 (USD per GBP) = 564.0 GBP2024/MWh
RD1 3 per cent 564.0 GBP2024/MWh
RD1 10 per cent 930.3
RD2 3 per cent 921.7
RD2 10 per cent 1,791.1Result: RD1 GBP564.0/MWh at 3 per cent and GBP930.3 at 10 per cent; RD2 GBP921.7 and GBP1,791.1. All GBP2024 per MWh at 20-year life.
State what these are, because the label is doing work. These are a rebuild computed here
of NASA's study restated, not NASA's published numbers restated. The distinction is carried
explicitly in CLM-0390's limits field and must not be dropped, because a reader who takes
GBP564/MWh as "NASA's figure in 2024 pounds" is reading a number that NASA never published at a
life NASA never used.
Where this fails. The Operate and Dispose lumps are 12-15 per cent of the lifecycle total (CALC-054) and are held fixed across a one-third reduction in system life. That is stated and its direction is stated, which is the right treatment, but it is not a rebuild of those lines. And the whole record inherits CALC-054's own limitation: an order-of-magnitude validation against NASA's published totals, not a reproduction of NASA's spreadsheet, which was not available.
Cross-reference, to prevent double-counting. The +22.0 / +29.3 / +21.6 / +9.4 per cent figures in CALC-061's Check B are the comparison of *this* record's output against the CRF shortcut. They are one measurement reported in two places and must not be counted as two.
Cite this
energyaperture.com/calc/calc-062
CALC-062. The working above, not a source document.