Lignin, the second most abundant component after cellulose in biomass, has been examined in this study as a fuel for direct conversion into electricity using direct carbon fuel cells (DCFC). Two different types of industrial lignins were investigated: Lignosulfonate (LS) and Kraft lignin (KL), in their commercial forms, after their blending with commercial active carbon (AC) or after alteration of their structures by a pH adjustment to pH 10. It was found that the open circuit voltage (OCV) of the DCFC could reach around 0.7 V in most of the trials. Addition of active carbon increased the maximum current density from 43-57 to 83-101 mA cm 22 . The pH adjustment not only increased the maximum current density but also reduced the differences between the two types of lignins, resulting in an OCV of 0.68-0.69 V and a maximum current density of 74-79 mA cm 22 from both lignins. Typical power density was 12 (for KL + AC) and 24 mW cm 22 (for LS + AC). It is concluded that a direct lignin fuel cell is feasible and the lignin hydrophilicity is critical for the cell performance.

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Keywords:Composite cathode perovskite oxide BCCF37 low temperature SOFC A B S T R A C T This work reports a new composite Ba x Ca 1-x Co y Fe 1-y O 3-d (BCCF) cathode material for advanced and low temperature solid oxide fuel cells (SOFCs). The BCCF-based composite material was synthesized by sol gel method and investigated as a catalytic cathode for low temperature (LT) SOFCs. XRD analysis of the asprepared material revealed the dominating BCCF perovskite structure as the main phase accompanied with cobalt and calcium oxides as the secondary phases resulting into an overall composite structure. Structure and morphology of the sample was observed by Field Emission Scanning Electron Microscope (FE-SEM). In particular, the Ba 0.3 Ca 0.7 Co 0.8 Fe 0.2 O 3-d (BCCF37) showed a maximum conductivity of 143 S cm À1 in air at 550 C measured by DC 4 probe method. The BCCF at the optimized composition exhibited much higher electrical conductivities than the commercial Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-d (BSCF) perovskite cathode material. A maximum power density of 325 mW cm À2 at 550 C is achieved for the ceria-carbonate electrolyte fuel cell with BCCF37 as the cathode material.

An advanced multifuelled solid oxide fuel cell (ASOFC) with a functional nanocomposite was developed and tested for use in a polygeneration system. Several different types of fuel, for example, gaseous (hydrogen and biogas) and liquid fuels (bio‐ethanol and bio‐methanol), were used in the experiments. Maximum power densities of 1000, 300, 600, 550 mW cm−2 were achieved using hydrogen, bio‐gas, bio‐methanol, and bio‐ethanol, respectively, in the ASOFC. Electrical and total efficiencies of 54% and 80% were achieved using the single cell with hydrogen fuel. These results show that the use of a multi‐fuelled system for polygeneration is a promising means of generating sustainable power.