SOEC Electrolyzers

solid oxide · co-electrolysis · syngas

Solid oxide cells run at 700-850 °C and need about a quarter less electricity per kilogram of hydrogen. Their edge is real only where a plant has waste heat and steam to feed them.

Bar chart of electricity per kilogram of hydrogen at system level: alkaline electrolyzers 50 to 55 kWh, PEM 50 to 58 kWh, solid oxide (SOEC) 37 to 40 kWh plus supplied heat. Below, co-electrolysis in one step: water and CO2 enter a solid oxide cell at about 750 degrees C and leave as hydrogen plus carbon monoxide, which feeds methanol or Fischer-Tropsch synthesis. ELECTRICITY PER KG OF HYDROGEN, SYSTEM LEVEL Alkaline 50-55 kWh PEM 50-58 kWh Solid oxide (SOEC) 37-40 kWh + heat CO-ELECTROLYSIS: ONE STEP TO SYNGAS H2O + CO2 SOEC 750 °C H2 + CO Methanol, FT
Operating temperature
700-850 °C
Electricity per kg H2
~37-40 kWh
Largest built
~2.6 MW
Companies tracked
9, 1 Chinese
Hub
Industry

Finding

SOEC cuts electricity per kilogram of hydrogen by about a quarter by substituting heat for power, which makes it the natural electrolyzer for ammonia, methanol and refinery sites with spare steam

Splitting water at 700-850 °C takes part of the energy as heat rather than electricity. With steam supplied from process heat, solid oxide electrolyzers need about 37-40 kWh of electricity per kilogram of hydrogen, against 50-58 kWh for alkaline and PEM units. They can also reduce CO2 and water together into syngas (H2 + CO) in one cell, skipping the separate reverse water-gas shift step.

The trade is durability and scale. Ceramic cells - yttria-stabilized zirconia electrolyte, nickel cermet and perovskite electrodes - degrade under thermal cycling and prefer steady operation, which fits a chemical plant better than a solar farm. The largest SOEC built is about 2.6 MW, Sunfire's MultiPLHY unit at Neste's Rotterdam refinery; most alkaline and PEM projects are 10-100 times larger. Topsoe opened an SOEC factory in Herning, Denmark and supplies First Ammonia's plant in Victoria, Texas; Bloom Energy ran a 4 MW unit at NASA Ames; Ceres Power licenses its solid oxide platform to Doosan in Korea, Delta in Taiwan and Weichai in China.

Green methanol from co-electrolysis needs a steady, non-fossil CO2 source - biogenic CO2 from ethanol or biogas plants, or direct air capture - which ties projects to specific sites. Whether SOEC or a cheaper alkaline system plus reverse water-gas shift wins depends on heat availability and stack life, not on cell efficiency alone. China dominates alkaline electrolyzers (LONGi Hydrogen, Peric, Sungrow Hydrogen); see Green Hydrogen Electrolyzers.

Compared

SOEC against low-temperature electrolyzers

Electrolyzer technologies compared
TechnologyTemperatureElectricity per kg H2Makes syngas directlyMain makers
Alkaline70-90 °C50-55 kWhNoLONGi Hydrogen, Peric, Sungrow Hydrogen, thyssenkrupp nucera, Nel
PEM50-80 °C50-58 kWhNoSiemens Energy, ITM Power, Plug Power, Cummins (Accelera)
Solid oxide (SOEC)700-850 °C37-40 kWh plus heatYes (co-electrolysis)Topsoe, Sunfire, Bloom Energy, Ceres Power licensees, Elcogen

Constraints

What limits SOEC scale-up

SOEC deployment constraints
ConstraintDetail
Stack durabilityDegradation from thermal cycling and high-temperature chemistry; steady operation preferred
Ceramics and interconnectsYSZ, doped ceria, perovskite electrodes and coated steel interconnects from a small supplier base
Heat integrationEfficiency advantage depends on cheap process steam
CO2 supplyCo-electrolysis needs captured CO2; biogenic and air-captured sources are limited
ScaleLargest units in the low megawatts; few multi-MW references

Vendors

SOEC and e-methanol suppliers

Solid oxide stack makers, then the licensors of CO2-to-methanol synthesis. Active companies first, then pilots, research groups and companies that exited.

SOEC and co-electrolysis
CompanyProductsHQTechnologyReference sitesStatus
Bloom EnergySOEC electrolyzersUSSOECactive
Ceres PowerSOEC stack technology licensed to manufacturersUKSOEC (steel-supported cells)active: Licensees include Doosan and Delta Electronics
ElcogenSolid oxide cells and stacksEstoniaSOEC, SOFCactive: Commercial collaboration with Shanghai Hyenergy
TopsoeSOEC stacks; eSOEC co-electrolysis; methanol and ammonia synthesisDenmarkSOECactive
EstoneSOEC and SOFC stacksChinaSOECpilot
SunfireSOEC co-electrolysis of steam and CO2 to syngasGermanySOECNorsk e-Fuel (Mosjoen)pilot
CO2-to-methanol synthesis
CompanyProductsHQTechnologyReference sitesStatus
Carbon Recycling InternationalEmissions-to-Liquids CO2-to-methanol plantsIcelandHydrogen plus CO2 methanol synthesisShunli plant, Anyang, China (with Geely)active
Johnson MattheyMethanol synthesis technology and catalystsUKeMethanol processactive
TopsoeMethanol synthesis technology and catalystsDenmarkeMethanol processactive

Sources

Sources and scope

Scope
SOEC Electrolyzers for Syngas and Methanol
Sources
IEA Global Hydrogen Review; Topsoe, Sunfire, Bloom Energy, Ceres Power disclosures; MultiPLHY project
Updated
October 2026