Low-carbon hydrogen and e-fuels: Engineering methods
Electrolysis, blue reforming and pyrolysis compared head to head
What this tab covers The engineering methods that can do this conversion, compared on efficiency, scale, economics, limitations and reliability.The routes differ in feedstock, CO2 handling and maturity.
Comparison
| Method | Efficiency | Scale | Economics | Limitations | Reliability |
|---|---|---|---|---|---|
| Electrolytic hydrogen (renewable, grid or nuclear power)14811 | 55 kWh/kg, 61% LHV (2022 PEM system) | Over 4 GW installed worldwide at end-2025; single projects up to 2.2 GW | Above USD 3/kg in the US (2022 status); much lower in China | Needs very cheap power and high running hours; grid power above 200-240 g/kWh is worse than gas | PEM stack life 40,000 hours (2022) |
| SMR with carbon capture ('blue')46 | 68.4% HHV, about 64% LHV (calculated) | About 480 t H2 a day per plant | USD 1.54/kg at 96.2% capture (2018 USD, US gas) | Upstream methane leaks and incomplete capture leave residual emissions | Mature |
| ATR with carbon capture6 | 67.9% HHV, about 64% LHV (calculated) | About 660 t H2 a day per plant | USD 1.51/kg at 94.5% capture (2018 USD) | Needs an air separation unit, CO2 pipeline and store | Early commercial at large scale |
| Coal (and biomass) gasification with capture46 | 64.1% HHV with capture (coal) | 133,000-660,000 kg/day | USD 2.92/kg coal; USD 3.44/kg with biomass co-feed (2018 USD) | 22-26 kg CO2-eq per kg if unabated; high capital cost | Commercial |
| Methane pyrolysis ('turquoise')7 | At most about 60% of methane energy to H2 (calculated) | Pilot to early commercial | About USD 1.50/kg claimed by one developer; a UK study in the review gives GBP 3.14/kg | Carbon markets are small; reactors foul with carbon | Unproven at scale |
Gas reforming with capture is today's cheapest low-carbon hydrogen where gas is cheap and a CO2 store is near (about USD 1.5/kg in US conditions), and ATR suits new plants because its CO2 is concentrated. Electrolysis has no fossil feed and its cost is falling fastest, mostly thanks to Chinese equipment, but is still dearer outside the best sites and only as clean as its power. Pyrolysis avoids CO2 storage but must prove scale and sell its carbon. Turning any of this hydrogen into ammonia, methanol or e-fuels loses a further share of the energy (see Power-to-X).
How each method works
Electrolytic hydrogen (renewable, grid or nuclear power)Electricity splits water in alkaline, PEM or solid-oxide electrolysers (see Electrolysers tile). Low-carbon only if the power is.
SMR with carbon capture ('blue')A conventional reformer with capture on the process gas and, for deep capture, on the furnace flue gas.
ATR with carbon captureOxygen from an air separation unit burns part of the gas inside the reactor, so the CO2 leaves in one concentrated stream.
Coal (and biomass) gasification with captureOxygen-blown gasifiers turn coal into syngas, then shift it and capture the CO2.
Methane pyrolysis ('turquoise')Plasma, microwaves, resistive heating or molten metal or salt crack methane into hydrogen and solid carbon; no CO2 store needed.
Sources
- Global Hydrogen Review 2026: Production International Energy Agency, 2026
- Global Hydrogen Review 2024: GHG emissions of hydrogen and its derivatives International Energy Agency, 2024
- Comparison of Commercial, State-of-the-Art, Fossil-Based Hydrogen Production Technologies (costs in 2018 USD) US DOE National Energy Technology Laboratory, 2022
- Recent Advances in Electrified Methane Pyrolysis Technologies for Turquoise Hydrogen Production (Rohani, Sudiiarova, Lyth, Badakhsh), Energies 18(9) 2393 MDPI, 2025
- Technical Targets for Proton Exchange Membrane Electrolysis US Department of Energy, Hydrogen and Fuel Cell Technologies Office, 2023
- thyssenkrupp nucera General Investor Presentation, May 2026 thyssenkrupp nucera, 2026