Efficient conversion of ethanol to electricity using large-scale flat-tube solid oxide fuel cells

Abstract

Conversion of renewable energy sources like bioethanol to electricity using solid oxide fuel cells (SOFCs) is promising to reduce the consumption of fossil fuels and to mitigate global warming. However, direct ethanol-fed SOFCs are susceptible to carbon deposition on Ni-based anode. In this study, the power generation from and degradation mechanism of large-scale flat-tube SOFCs by direct internal reforming of ethanol are investigated. The steam/carbon (S/C) ratio causes minor influence on the cell performance but considerably affects the long-term durability. Elevating temperature improves ethanol conversion rate and cell performance. Ethanol is efficiently reformed by the thick anode support and long anode channels, with low selectivity for CH4 and C2H4. Stable power generation with current density of 200 mA/cm2 is obtained over 300 h under S/C = 2 and 3 at 800 °C. Due to the high operating temperature and complex cell structure, the in-situ measurements of the temperature and gas compositions within the cell, related to carbon deposition, are difficult. The distributions of the gas compositions and temperature within the cell before and after the durability test are clarified by simulation. Simulation results reveal that, in addition to CH4 and C2H4, the cold zone near inlet contributes to carbon formation.