Direct utilization of lignite coal in a Co–CeO 2 /YSZ/Ag solid oxide fuel cell

Abstract

Available online xxxKeywords: Direct carbon fuel cells Lignite fuel Co/CeO 2 anode Carbonates a b s t r a c t The feasibility of employing lignite coal as a fuel in a Direct Carbon Fuel Cell (DCFC) of the type: lignitejCoeCeO 2 /YSZ/Agjair is investigated. The impact of several parameters, relatedto anodic electrode composition (20, 40 and 60 wt.% Co/CeO 2 ), cell temperature (700 e800 C), carrier gas composition (CO 2 /He mixtures), and total feed flow rate (10e70 cm 3 / min), was systematically examined. The effect of molten carbonates on DCFC performance was also investigated by employing a eutectic mixture of lithium and potassium carbonates as carbon additives. In the absence of carbonates, the optimum performance (~10 mW cm À2 at 800 C), was achieved by employing 20 wt.% Co/CeO 2 as anodic electrode and pure CO 2 as purging gas. An inferior behavior was demonstrated by utilizing He instead of CO 2 atmosphere in anode compartment and by increasing purging gas flow rate.Carbonates infusion into lignite feedstock resulted in a further increase of maximum power density up to 32%. The obtained findings are discussed based also on AC impedance spectroscopy measurements, which revealed the impact of DCFC operating parameters on both ohmic and electrode resistances.

Assessment of biochar as feedstock in a direct carbon solid oxide fuel cell

“…The different reactivity of biochar fuels towards CO 2 (Figure 7) resulted in a different amount of produced CO, which in turn affects the overall DCFC performance. [22][23][24] The key role of CO on DCFC characteristics has been already demonstrated in our relevant previous studies. This pronounced behavior can be attributed to the influence of CO on anode reducibility 23 as well as to its faster electro-oxidation kinetics compared to solid biochar.…”

“…The corresponding open circuit AC impedance spectra at 700, 750 and 800 o C, obtained at conditions identical to those employed in Fig. 23 Similarly, the electrode resistance is notably influenced by the fuel type and the operation temperature. 8.…”

“…19 Among them, SOFCs is an already commercialized technology, offering the well-known advantages of oxygen anion (O 2-) conducting ceramic SOFCs, such as thermal stability and fuel flexibility. 18,[22][23][24] However, in most DCFC studies the most commonly used fuel is carbon black. Lately, in order to overcome the restrictions imposed by the currently employed SOFC configurations, a hybrid carbon fuel cell (HCFC) concept has been proposed.…”

Comparative study of durability of hybrid direct carbon fuel cells with anthracite coal and bituminous coal

“…The highest maximum power density of 71.88 mW cm -2 is obtained by the cell with B-II fuel. This power output obtained in this study is on the top level among reports in literature concerning electrolyte-supported cells 4,12,18 . The values achieved here are better than those of cells operating at a higher temperature (850 °C), even though a thinner YSZ electrolyte (0.5 mm) and a composite electrode of Ni-GDC-YSZ are used.…”

“…8 The gasification of lignite was sensitive to the carrier gas. In the presence of CO 2 , lignite was gasified into CO at 800 °C, and therefore, resulted in a good cell performance 12 . Anodic electrode composition, carrier gas composition and flow rate, and a carbonate addition were important parameters and these were therefore optimised.…”