Syntholene completed construction of its Husavik, Iceland eSAF demonstration facility on June 22, six months ahead of its original schedule and under budget, the company said in a release. Construction took 69 days from permit issuance, with the central Thermal Coupling Heat Exchanger fabricated in 42 days. The plant pairs Syntholene’s Solid Oxide Electrolyzer Cell (SOEC) technology with geothermal heat at the historic Husavik power station, in what the company describes as the first geothermally-integrated high-temperature electrolysis demonstration for eSAF anywhere in the world.
The technoeconomic case for SOEC over conventional low-temperature electrolysis runs through the heat balance. Splitting water into hydrogen at 700 to 850 °C requires less electricity than at 80 °C, but it requires high-grade heat to do it. In a fully integrated power-to-liquids plant, Fischer-Tropsch synthesis is exothermic and its waste heat can typically cover the SOEC steam duty, which is how Sunfire and Topsoe reference designs preserve the efficiency advantage. A geothermally-coupled SOEC unbinds the steam supply from the FT loop and lets the electrolyzer run on dispatchable thermal energy independent of synthesis-loop heat recovery — useful for demonstration-scale operation where the FT side may not be running at design capacity, and potentially useful for hybrid configurations at larger scale.
Completing a first of its kind energy facility ahead of schedule and under budget is rare.
“Completing a first of its kind energy facility ahead of schedule and under budget is rare,” said CEO Dan Sutton. Effects testing and data gathering will commence shortly, the company said, with initial efficiency and technoeconomic results targeted for publication by Q4 2026.
What the release does not disclose is the demonstration unit’s eSAF output capacity, the project budget figure, the geothermal supplier on the steam side, or any offtake counterparty. Husavik historically draws on the Þeistareykir geothermal field operated by Iceland’s state utility Landsvirkjun, but Syntholene’s release does not name a supplier or a commercial steam-take agreement.
What to watch through the rest of 2026: the Q4 efficiency and technoeconomic disclosure is the first real test of whether geothermal-integrated SOEC clears the thresholds eSAF will need to compete inside ReFuelEU’s synthetic aviation fuel sub-target — the e-SAF carve-out that ramps from 1.2% in 2030 to 2% in 2032 to 5% by 2035 — at unit economics that hold up beyond the demonstration envelope.
Source: Syntholene Energy press release
