Advanced fuel cells: from materials and technologies to applications

Fuel cells are a promising future energy technology to provide effective conversion from fuel to electricity.Fuel cells can be utilized in a wide range of applications and over a broad power scale.To become commercially viable, major progress both in the science and technology of fuel cells is necessary.Advanced fuel cell technologies such as lowtemperature solid oxide fuel cells (SOFCs), utilization of nano-materials, improved theoretical understanding of new fuel cell materials, and better fuel cell system optimization, are examples of approaches leading to more effective technology.This special issue of the International Journal of Energy Research focuses on advanced fuel cell technology and covers topics from materials and technologies to applications.It includes nine selected papers.Some of the papers were presented at the EC-China NANOCOFC workshop in connection with the Sixth China International Conference on High-Performance Ceramics in August 2009 in Harbin.Many of the papers deal with advanced SOFCs.The papers in this special issue include information on recent progress in fuel cells.This should be of interest to journal readers working with science, technology or applications of fuel cells.In the following, highlights from each of the nine papers are presented.Yuan et al.[1] modelled an intermediate temperature SOFC poly-generation system fueled by ethanol and demonstrated a high overall efficiency.The exhaust gas had a high value in use. Sun et al.[2] investigated a novel perovskite-like oxide for low-temperature SOFCs operating at 400-600 C. The authors demonstrated a power density exceeding 300mW/cm 2 . McIlveen-Wright et al.[3] performed a techno-economic analysis of integrated biomass gasifiers for intermediate temperature (IT) and low-temperature (LT) SOFC.Using willow and miscanthus as feedstock, 38-39% fuel cell efficiencies were found. Timurkutluk et al.[4] investigated the infiltration of nano-ion conductors to the anode and cathode side to improve SOFC performance.The power density could be increased even by a factor of two through the infiltration, but the particle size and the porosity affected the results.Tosto [5] analyzed mixed ionic-electronic conductivity in solid oxides in the presence of point and line lattice defects.Presence of dislocations in the crystal lattice causes a drift force additional to that due to the concentration and electric potential gradients and explains increased conductivity.Malkow et al.[6] have developed a harmonized testing procedure for polymer electrolyte membrane fuel cell power stacks using polarization measurements.The assessment of the stack performance is based on a statistical approach of the test outputs.Ferreira et al.[7] discussed composite ionic conductors for fuel cells.They found that in addition to mixed carbonate phase, unexpected composite effects may influence charge transport properties.Grain sizes and interfacial layers with nano-sized crystals also were investigated.Lund [8] analyzed poly-generation systems based on fuel cells and showed that not only the performance parameters but also the characteristics of the end-use application will determine the energy benefits.About 10-20% primary energy savings can easily be achieved with LT-SOFCs.