Biogas operated proton ceramic fuel cells with novel S-tolerant functional materials

Biogass er en fornybar energikilde som kan brukes som brensel i for eksempel proton-keramiske brenselceller (PCFC) for produksjon av elektrisitet. Siden biogass inneholder mye hydrogensulfid (H2S) må elektrolytten og anoden på brenselsiden være tolerante til svovel. Prosjektet har som mål å utvikle svovelholdige og/eller svovel-tolerante PCFC for bruk med urenset biogass. Vi har bekreftet at protonledende Y-dopet BaZrO3 (BZY) er stabilt og kan brukes som elektrolytt. Vi har videre studerert anoder der det tradisjonelle men S-intolerante Ni byttes ut med oksid- og sulfidbaserte materialer. En serie med jern- og molybdenholdige perovskitt-oksider er funnet å ha tilfredsstillende egenskaper. En lab for sikkert arbeid med H2S-holdige atmosfærer er etablert ved SINTEF og en brenselcelle med de velgte materialene er testet med kunstig biogass. De eksperimentelle studiene ved UiO støttes av teoretiske beregninger og modellering av struktur og termodynamikk av sulfider, oksysulfider, og oksysulfater ved SINTEF. Arbeidene er publisert eller under publisering.

The BioPCFC project will build basic knowledge on materials science and engineering for enabling with waste biogas fuelling of Proton Conducting Solid Oxide Fuel Cells. The novel functional materials will have a sulphur tolerance enabling robust and flexi ble fuelling from various renewable waste feedstocks. Foreseen advantages of this distributed combined heat and power technology using renewable sources are improved electrical efficiency (> 40%), and negligible levels of NOx and SOx pollutants compared t o competing combusting engines and microturbines. The BioPCFC project addresses main problems of fuel cell efficiency and sulphur (S) tolerance in high temperature proton conducting fuel cells (PCFC) along three entirely novel routes with increasing risk/ reward impact, related to the functional properties of materials in the anode and the electrolyte. Stable proton conducting solid oxide electrolyte with a controlled minor oxide ion contribution will be studied to achieve higher fuel utilization and suppl y of remaining H2O in the anode for internal reforming of CH4 and oxidation of CO. These are expectedly stable towards H2S. The project additionally includes a pioneering investigation of proton and oxide ion transport in sulphates, oxosulphates, and mixe d oxoacid salts that are stable at high temperatures in the presence of SO2 and are hitherto unexplored in terms of ionic transport. Partial (or in principle full) replacement (alloying) of Ni by less noble metals, like Co, Fe, and Mn will be explored tak ing benefit of the more reducing atmosphere of PCFC anodes. Finally novel pathways for anode concepts in BioPCFC will include novel mixed proton-electron conducting electrocatalysts, proton and hydrogen in metallic oxides, transport of neutral hydrogen in oxides and sulphur-containing compounds. The project is coordinated by UiO with SINTEF as partner. It lasts 3 years and educates 1 Postdoc. candidate.