Glossary#

Terms as used in the HyFlux codebase and this documentation.

ASK#: Available seat-kilometre — seats offered × distance flown. The cost comparison reports per-ASK figures (computeASK).
ATK#: Available tonne-kilometre — payload capacity × distance flown.
ATJ#: Alcohol-to-jet — SAF pathway converting alcohols to jet fuel (feedstock category SS, CI 32.8 gCO₂e/MJ default).
BAU#: Business as usual — the gross emissions trajectory with no decarbonisation wedges applied.
BOR#: Boil-off recovery — fraction \(f_{BOR}\) of evaporated hydrogen recaptured rather than vented (bor, default 50 %).
CAGR#: Compound annual growth rate — traffic growth input (default 3.5 %/yr); multi-segment via cagrPeriods.
CGI#: Custom Global Initiative — long-horizon CORSIA extension to 2100; implemented per DL-044 (cgi_enabled, cgi_gamma_end; constrained offset mode only — Traffic Growth, Carbon Offsets & Removals).
CI#: Carbon intensity — life-cycle emissions per unit fuel energy, gCO₂e/MJ (WTW unless stated).
CORSIA#: Carbon Offsetting and Reduction Scheme for International Aviation — ICAO scheme; the sectoral subset (SEB/SGF) runs in production, and operator-level accounting (OEB/OGF/w(t)) is implemented standalone (Carbon Offsets & Removals).
DAC / DACCS#: Direct air capture (and storage) — removal pathway and CO₂ source for PtL/PtG fuels; default capacity 5,000 MtCO₂/yr at 2050.
DL#: Decision-log entry — ENGINEERING_DECISION_LOG.md provenance record (platform series DL-001…DL-164; the v5 publication series V5-DL-061… is logged separately in docs/decision-log-v5.md).
EIS#: Entry into service — first year a future aircraft type operates; internally decremented (\(t_{EIS} = t^*_{EIS} - 1\)).
EJ#: Exajoule — 10¹⁸ J; the energy-demand roll-up’s unit.
FAO#: Fleet & Airport Operations — operations efficiency category (ambition 0.8–4.0 %).
FOG#: Fats, oils and greases — SAF feedstock category (HEFA-UCO, CI 13.9 gCO₂e/MJ default).
FT#: Fischer–Tropsch — synthesis converting CO/H₂ to liquid hydrocarbons; basis of FT-SAF and the PtL pathways.
GH2#: Gaseous hydrogen — PtL/PtG feedstock form, tracked separately from LH₂ aircraft fuel (no liquefaction/boil-off terms).
GWP100#: Global warming potential over 100 years — H₂ ≈ 11.6, CH₄ ≈ 29.8 (claim register BC-12; citation attribution recorded as an open evidence gap [Sand et al., 2023]).
HEFA#: Hydroprocessed esters and fatty acids — leading near-term SAF pathway (HEFA-UCO).
HTS / SC#: High-temperature superconducting — motor technology lever (sc) in HyFlux’s extension analysis.
JGE#: Jet-gallon-equivalent — 0.131354 GJ; the cost module’s per-gallon normalisation.
LCAF#: Lower-carbon aviation fuel — fossil jet with reduced upstream emissions (CI 65 gCO₂e/MJ default).
LF#: Load factor — share of seats (or payload) filled; energy multiplier via RPTK conservation (Operations).
LH2#: Liquid hydrogen — cryogenic aircraft fuel; delivered CI includes liquefaction, vapor loss and boil-off recovery.
LHV#: Lower heating value — energy basis throughout (Jet-A 43.2, H₂ 120, CH₄ 50 MJ/kg).
MACC#: Marginal abatement cost curve — per-strategy marginal abatement cost \(MAC_{stype}\) is implemented in the standalone CASCADE cost model (cost-model.ts, DL-134); the production economics block still reports per-pathway removal cost/capacity pairs and the blended average (Costs).
NEC#: Non-edible crops — SAF feedstock category (FT-Miscanthus, CI 20.2 gCO₂e/MJ default).
OGF#: Operator Growth Factor — CORSIA operator-level accounting term; implemented standalone with OEB, the w(t) schedule and the CGI operator analogues (routes/corsia-operator.ts, corsia-aggregation.ts; DL-045/046/137) — not wired into the production sweep, operator set synthetic (Carbon Offsets & Removals).
PtG#: Power-to-gas — e-methane synthesis (CO₂ + 4H₂ → CH₄ + 2H₂O); pathway added DL-032.
PtL#: Power-to-liquid — e-fuel jet pathway (electrolysis + RWGS + FT); CI tracks electricity and GH₂ carbon intensity (DL-024).
RNG#: Renewable natural gas — bio-methane from waste biogas (WTW CI 22 gCO₂e/MJ default).
RPTK#: Revenue passenger tonne-kilometre — payload traffic conserved by the load-factor formulation.
RTK#: Revenue tonne-kilometre — total revenue payload traffic.
RWGS#: Reverse water-gas shift — CO₂ + H₂ → CO + H₂O; first step of PtL synthesis.
SAF#: Sustainable aviation fuel — drop-in jet fuels blended per feedstock (Energy Carriers).
SEB#: Sectoral Emissions Baseline — CORSIA baseline, 0.85 × 2019 sector emissions.
SGF#: Sectoral Growth Factor — CORSIA offset share \(\max(0, (G - SEB)/G)\).
SMR#: Steam methane reforming — fossil hydrogen production (\(CI_{SMR} = 0.045\,CI_{elec} + 85.95\)).
SS#: Sugars and starches — SAF feedstock category (ATJ).
TTW#: Tank-to-wake — combustion-only emissions (Jet-A1 74 gCO₂e/MJ).
WAR#: Wastes and residues — SAF feedstock category (FT-MSW, CI 28.4 gCO₂e/MJ default).
WTW#: Well-to-wake — full life-cycle emissions (Jet-A1 89 gCO₂e/MJ); the engine’s canonical basis.