HEFA vs PtL, the crossover math.
Two pathways, two different constraint shapes. HEFA is feedstock-limited and cheap. PtL is capex-heavy and unbounded. The question for every investor is not which is better today · it is when the curves cross. Here's the math, updated against our live feedstock index.
The two cost stacks, 2026
Pathway costs reduce to three levers: feedstock, conversion, and capex amortisation. What makes HEFA and PtL behave differently as a market is how those levers scale · with output volume, with renewable-electricity prices, and with feedstock availability.
HEFA · the feedstock-bound pathway
| Component | 2026 cost ($/t SAF) | Driver |
|---|---|---|
| Feedstock (UCO / tallow) | 1,000 - 1,350 | Used cooking oil + Cat 1/2 tallow, see our live index |
| Hydrogen (grey H₂) | 80 - 130 | ~40 kg H₂ per tonne SAF |
| Conversion opex | 150 - 220 | Hydrotreating energy + catalyst |
| Capex amortisation | 220 - 300 | $400-600M plant, 20y life, $1-1.5B/Mt capacity |
| Total | 1,450 - 2,000 | vs fossil jet ~$650/t |
HEFA today clears the market at roughly 2.5-3× fossil jet. The primary variable cost is feedstock · ~70% of the stack. That is also the pathway's constraint.
PtL · the capex-bound pathway
| Component | 2026 cost ($/t SAF) | Driver |
|---|---|---|
| Renewable electricity | 1,800 - 2,600 | ~25 MWh per tonne SAF at $70-105/MWh PPA |
| Green hydrogen (electrolysis) | 900 - 1,400 | Implied by electricity above · electrolyser efficiency |
| CO₂ (biogenic / DAC) | 250 - 650 | ~3.2 t CO₂ per tonne SAF |
| Conversion + FT opex | 200 - 300 | Fischer-Tropsch + upgrading |
| Capex amortisation | 900 - 1,600 | $1.5-2.5B plant, 20y life, $3-5B/Mt capacity |
| Total | 4,050 - 6,550 | vs fossil jet ~$650/t |
PtL today clears at 6-10× fossil jet. The primary variable cost is renewable electricity · 45-55% of the stack. Capex is the second-largest line · there is no analogue to HEFA's feedstock ceiling.
The constraint shape · why the curves cross
HEFA has a physical ceiling. Global annual supply of eligible lipids (UCO, tallow, high-quality waste oils) is roughly 25-35 million tonnes per year. Converted at ~80% mass yield, that is 20-28 Mt of HEFA-SAF equivalent · roughly 7-9% of projected 2035 jet-fuel demand. Beyond that ceiling, HEFA feedstock prices spike (fraud risk, food-grade competition, collection logistics) and the cost stack moves the wrong way.
PtL has no feedstock ceiling. Renewable electricity, green hydrogen, and CO₂ are effectively unbounded at the relevant time horizons. What PtL has instead is a learning curve · each doubling of installed electrolyser capacity delivers roughly 15-18% cost reduction (observed historical rate). Modular manufacturing of Fischer-Tropsch skids targets similar experience-curve economics.
HEFA stays cheap until supply hits its ceiling. PtL stays expensive until capex walks down its learning curve. The crossover is the intersection of those two curves.
Our base case for the intersection sits between 2034 and 2038 · depending on three levers: (a) how fast renewable electricity prices fall (base case: $50/MWh by 2032 in the best PPA regions), (b) how tight HEFA feedstock gets (base case: UCO-equivalent prices double by 2032), and (c) how the ReFuelEU e-SAF sub-mandate accelerates PtL deployment independent of economic crossover.
What the mandates do to the equation
A rational market without regulation would pick HEFA until feedstock exhausted, then accept a price-spike transition period, and only then build PtL capacity. Three live mandates refuse to wait.
- ReFuelEU e-SAF sub-mandate forces PtL deployment from 2030 (1.2%) regardless of economics. This is the single largest demand-side signal for PtL globally.
- UK Revenue Certainty Mechanism directly backstops PtL revenue, effectively short-cutting the learning curve for UK-sited plants.
- US §45Z with its $1/gal cap post-OBBB does the opposite · it mutes the HEFA-to-PtL gradient by paying both the same rate.
Stack those three: European e-SAF policy pulls PtL capacity forward by 5-8 years versus economic-only base case. UK subsidy concentrates the earliest large-scale plants in Britain. US policy treats pathway choice as neutral, reinforcing HEFA's near-term advantage there.
Implications for producers and investors
Three distinct commercial windows exist right now:
- HEFA, 2025-2032 · feedstock-secured plants with long-dated UCO supply contracts can clear markets at §45Z + SAF-premium pricing. Bankable with high-quality offtake. Risk: feedstock supply tightens faster than expected.
- PtL, 2028-2035 · European-sited plants leveraging RCM / Innovation Fund grants clear through ReFuelEU's e-SAF sub-mandate. Risk: electrolyser-technology execution on first commercial-scale plants.
- ATJ + G-FT, 2030-2040 · alcohol and waste-gasification pathways occupy the middle ground as HEFA-feedstock runs out and PtL technology matures. See our SAF technology overview for the full six-pathway map.
Investors structuring SAF exposure in 2026 need a portfolio view, not a single-pathway thesis. Fund the near-term HEFA operators who lock feedstock contracts early. Fund the European PtL FIDs where the e-SAF sub-mandate + RCM de-risks long-dated revenue. Monitor the ATJ/G-FT learning curves as the crossover arrives in the mid-2030s.
Our methodology
The cost stacks above are updated monthly against our feedstock price index and published project tracker. Renewable electricity price ranges reflect the 2026 Q1 P25-P75 spread across European and US PPA auctions. Electrolyser capex uses our Electrolyser CAPEX commodity tracker · currently $900/kW installed, trending to $500/kW by 2030 per BNEF/IEA consensus.
For the raw data underpinning the numbers, see the feedstock prices module. For the mandate overlay, see the regulatory module. For the project pipeline, see the market intelligence module.