Integrated Operation of the INL HYTEST System and High-Temperature Steam Electrolysis for Synthetic Natural Gas Production

The primary feedstock for synthetic fuel production is syngas, a mixture of carbon monoxide (CO) and hydrogen. Current hydrogen production technologies rely upon fossil fuels and produce significant quantities of greenhouse gases as a by-product. This is not a sustainable means of satisfying future hydrogen demands given the current projections for conventional world oil production and future targets for carbon emissions. For the past 6 yr, the Idaho National Laboratory (INL) has been investigating the use of high-temperature steam electrolysis (HTSE) to produce the hydrogen feedstock required for synthetic fuel production. HTSE water-splitting technology, combined with non-carbon-emitting energy sources, can provide a sustainable, environmentally friendly means of large-scale hydrogen production. Additionally, laboratory facilities are being developed at the INL for testing hybrid energy systems composed of several tightly coupled chemical processes (HYTEST program). The first such test involved the coupling of HTSE, a CO₂ separation membrane, the reverse-shift reaction, and the methanation reaction to demonstrate synthetic natural gas production from a feedstock of water and either CO or a simulated flue gas containing CO₂. This paper will introduce the initial HTSE and HYTEST testing facilities, overall coupling of the technologies, testing results, and future plans.