Progress and outlook for solid oxide fuel cells for transportation applications

Abstract

With their high temperatures and brittle ceramic components, solid oxide fuel cells (SOFCs) might not seem the obvious fit for a power source for transportation applications. However, over recent years advances in materials and cell design have begun to mitigate these issues, leading to the advantages of SOFCs such as fuel flexibility and high efficiency being exploited in vehicles. Here we review the advances in SOFC technology which have led to this, look at the vehicles that SOFCs have already been used in, and discuss the areas which need improvement for full commercial breakthrough, and the ways in which catalysis science can assist with these. In particular we identify lifetime and degradation, fuel flexibility, efficiency and power density for improvement, and areas of catalysis science ranging from surface science and computational materials design to improvements in reforming catalysts and reformer design as key to this. MainDecarbonising transport is one of the largest challenges in the global response to climate change. Globally, transport is responsible for 23% of emissions and currently relies on hydrocarbons for 92% of its energy 1 . Decarbonisation is particularly difficult for transportation, because one of the key requirements for the energy source is portability, and hydrocarbons are one of the most energy dense substances available. In addition, the public health burden from pollutants such as particulates, nitrogen oxides and sulfur oxides emitted by vehicles is large, so cleaner energy sources are required.Efforts in transportation have focussed on batteries and polymer electrolyte fuel cells (PEFCs) running on hydrogen, alongside efficiency improvements and fuel switching. Although over the last decade batteries have been the dominant technology because they have advantages over fuel cells in manufacturing, cost, responsiveness in a vehicle and availability of supporting infrastructure, in the longer-term fuel cells may have advantages in some areas. The clearest advantage of fuel cells is high energy density, where it's not known whether battery technology will ever advance far enough to power long-distance transportation such as ships or intercontinental flights. In the area of passenger vehicles, with high battery vehicle penetration, much of the local grid infrastructure such as substations may not be able to cope and may have to be replaced -it is not clear at the moment whether this will be more expensive and disruptive than the rollout of the hydrogen-fuelling network which would be needed to support fuel cell vehicles. In applications such as buses where fast charging/refuelling is needed, fuel cells also possess an innate advantage. Finally, the wider advantage of switching to a hydrogen-fuelled transportation system is that electrolysers can be used to smooth the intermittent supply from renewable energy, while at the same time producing hydrogen fuel for vehicles.One technology which was until relatively recently deemed unsuitable for transportation, but nevertheless has unique ad...

Comprehensively Probing the Contribution of Site Activity and Population of Active Sites toward Heterogeneous Electrocatalysis

“…In response to the growing energy demand but the finite supply, i. e., fossil fuels, the energy‐related issues have been focused on exploring renewable and sustainable sources . Among the myriad alternatives, research in the field of electrochemical heterogeneous catalysis is in majority with more than ten thousand published articles per year.…”

A membraneless microfluidic fuel cell with a hollow flow channel and porous flow‐through electrodes

“…A variety of fuel cells are being developed to convert chemical energy into electrical energy. [1][2][3][4][5][6][7][8][9] Fuel cells have no emissions, better energy density, 10 and could supply power in applications ranging from miniature electronic devices to big plants. Most fuel cells use a proton exchange membrane (PEM) to carry out the electrochemical reactions.…”

“…Numerous MMFCs have been developed with different fuel-oxidant combinations, microchannel configurations, and electrode materials. [2][3][4][5][6][7][8][9] Multiple studies have been carried out to improve an MMFC's fuel utilization, crossover issues, mass-transport and Ohmic losses, and lower volumetric power density, which are considered as main setbacks. [27][28][29][30] Lower fuel utilization in MMFCs is caused by slow reaction rates at the cathode, including slow oxygen reduction, different fuel-oxidant kinetic properties, and triple phase solid-liquid-gas interactions, which are common conditions on the cathode side.…”

“…A variety of fuel cells are being developed to convert chemical energy into electrical energy 1‐9 . Fuel cells have no emissions, better energy density, 10 and could supply power in applications ranging from miniature electronic devices to big plants.…”

“…Kjeang et al 27 comprehensively reviewed the operation and applications of MMFCs. Numerous MMFCs have been developed with different fuel‐oxidant combinations, microchannel configurations, and electrode materials 2‐9 . Multiple studies have been carried out to improve an MMFC's fuel utilization, crossover issues, mass‐transport and Ohmic losses, and lower volumetric power density, which are considered as main setbacks 27‐30 .…”