Demonstration of a Liquid-Tin Anode Solid-Oxide Fuel Cell (LTA-SOFC) Operating from Biodiesel Fuel

Abstract

In this paper, the authors present the first demonstration of a liquid-tin anode solid-oxide fuel cell (LTA-SOFC) operating on pure biodiesel (B100) prepared via base-catalyzed transesterification of virgin and waste cooking oils. The LTA-SOFC was able to convert the biodiesel to electricity at commercially viable power densities, i.e., greater than 100 mW cm−2. The peak power for each cell was 3.5 W over an active area of 30 cm−2, which translates to a power density of 117 mW cm−2 and current density of 217 mA cm−2. The peak power densities correspond to ∼80% fuel use at the liquid-tin anode surface and overall cell efficiencies of >40%. These findings demonstrate the flexibility in operating a solid-oxide fuel cell capable of internal reforming from a blend of petroleum- and biomass-derived diesels for greater resource flexibility. Cells were operated for short times (∼4.5 h), owing to the experimental nature of the balance of plant. Results support future efforts in developing an efficient balance-of-plant system for demonstrating long-term (>1000 h) power generation from biodiesel using the LTA-SOFC design.

A review of liquid metal anode solid oxide fuel cells

“…It is well known that SOFCs (similar to other fuel cells) can be detrimentally affected by power demand surges during operation, since such surges can cause fuel starvation, which in turn may cause irreversible structural changes at the electrodes. The presence of a certain amount of LMA acts as a metal-oxygen battery, where the metal itself is oxidised to provide sufficient load [4,5,7]. The oxidised metal can be reduced again by the fuel fed into the anode when normal load is resumed.…”

“…Various fuels have been studied for LTA SOFCs including biodiesel [5], military fuels, such as JP-8 [6,11,13], gasoline, methane, etc. All these studies confirm the LTA SOFC fuel flexibility.…”

“…It has been pointed out that interactions between the liquid tin anode and fuel have not been systematically studied and that better modelling and a fundamental study is needed. Direct conversion of biodiesel has been demonstrated using the LTA SOFC [5]. In an approach similar to that adopted for JP-8, a tubular LTA SOFC cell was tested for 4.5 h with biodiesel (B100) prepared from virgin and waste cooking oils [5].…”

“…In this regard, several studies [4][5][6][7] have presented novel concepts for the direct electrochemical oxidation of carbon (coal or biomass) for highly efficient electricity generation using Liquid Metal Electrode Solid Oxide Fuel Cells (LME SOFCs). This new class of fuel cell offers the advantage of high efficiency with the benefits of greater fuel tolerance, the concept being particularly well suited to the direct use of solid fuel.…”

“…Some of the earliest work on liquid metal electrodes was reported by Cell Tech Power, who used liquid tin as their anode material of choice [5,6,11,12] and achieved a power density of 170 mW cm −2 on hydrogen and JP-8 fuel [4]. The projected efficiency of such a system operating on coal is 61 % [13].…”