A new demonstration facility in northern Iceland will integrate geothermal energy with a solid-oxide electrolyzer cell (SOEC) to produce green hydrogen, representing a key step toward lower-cost sustainable aviation fuel (SAF). This Thermal Hybrid Production System, developed by Syntholene Energy Corp. (Chicago, Ill.; www.syntholene.com), takes advantage of the “significant thermal energy stored in geothermal fluid to produce ultra-pure steam at exactly the right temperature and pressure required for input to industrial SOEC modules,” explains Jack Williams, head engineer at Syntholene.
Source: Dynelectro
The geothermal fluid enters the system at high pressure as the hot-side input into Syntholene’s novel configuration of high-efficiency heat exchangers, transferring heat to ultra-pure water. Since the same geothermal fluid generates the power required by the SOEC module, it provides both the required heat and electricity to produce hydrogen. External energy inputs for steam generation are a considerable cost in SOEC plants, and conventional SAF plants often couple their electrolyzer systems to intermittent power sources, such as wind and solar. “Individually, neither geothermal energy nor SOEC technology provides a decisive advantage, but their direct integration is transformative: geothermal fluid allows production of inherently low-cost steam with no additional heat input, enabling the SOEC’s roughly one-third lower electricity demand per kilogram of hydrogen to translate directly into reduced levelized cost of hydrogen,” says Williams.
The technology has been demonstrated at the laboratory scale at Idaho National Laboratory (www.inl.gov), and is now being integrated with a live geothermal resource in Húsavík, Iceland, to demonstrate hydrogen production at industrially relevant scales, which Williams says will help to validate that “direct integration of geothermal energy with high-temperature SOEC technology can materially reduce the cost of hydrogen production.”
Following this demonstration, the company plans to install a commercial facility, targeting production of around 20,000 metric tons per year (m.t./yr) of SAF, supported by an Expression of Interest from airline IcelandAir. This commercial-scale project is expected to require a minimum of 45 MW of SOEC capacity. For its demonstration site in Iceland, Syntholene is deploying a 250-kW SOEC unit provided by Dynelectro ApS (Sjælland, Denmark; www.dynelectro.dk). Dynelectro’s proprietary electrolyzer units enable dynamic operation and extremely high electrical efficiency.