Redefining Ceramic Fuel Cells

I just read this by Jeff Basch, John Halloran,  and Timothy LaBreche



From ceramicindustry.com

The future of alternative energy lies in the ability to deliver portable power to market.

Wikipedia’s community of experts can’t overcome incorrect assumptions on the emerging alternative energy space. Wikipedia’s solid oxide fuel cell (SOFC) entry, which describes SOFCs as devices that use a solid (ceramic) electrolyte to facilitate the generation of energy, notes that these fuel cells are “intended mainly for stationary applications.” In fact, leading innovators are proving that ceramic fuel cells can include small and light energy devices. Indeed, the future of alternative energy lies in the ability to deliver this portable power to market.



Portable power is the holy grail of alternative energy research. Small, lightweight energy devices bridge the gap between the current market leaders, batteries and gas generators. Batteries become heavier as power output rises, and gas generators become noisier and produce ever-increasing pollution in tandem with increases in power output. In contrast, SOFCs deliver a wide range of energy output, between 20 and 250 watts, making them incredibly energy-dense for their weight and size. 

Besides providing portable power, SOFCs offer a huge advantage over typical proton exchange membrane (PEM) fuel cells. PEM requires very pure hydrogen fuel, which is costly and difficult to obtain. In addition, PEM fuel cells require expensive platinum catalysts that are poisoned by many low-level contaminants such as carbon monoxide and sulfur. In contrast, SOFCs are fueled by readily available bottled propane or butane gas. Propane and butane are not expensive, and they are trusted and available at over 25,000 retailers in the U.S. alone

The fuel argument is strong.

Below is a propane-powered solid oxide fuel cell system weighing less than 1.5 kilograms and generating 600 watt-hours per day (equivalent to 20 D-cell batteries per day).

 Portable SOFCs based on a small tube design were originally developed by Professor Kevin Kendall of the University of Birmingham in the UK. Kendall realized that the disadvantages of the traditional SOFC design could be avoided if thermal-shock-sensitive planar stacks or large tubes were replaced with small tubes of a few millimeters in diameter.

Instead of conventional ceramic fabrication methods, these generators are produced through ceramic powder that is loaded in thermoplastics to undergo hot extrusion. Ordinary wet ceramic extrusion produces a soft tube, which forms a weak and brittle green tube after slow drying. In contrast, thermoplastic extrusion provides fast cooling to produce a strong and flexible green tube that can be manufactured with thinner walls. Thermoplastics do require binder burnout, which can be a problem with large sections but is no problem for thin-walled tubes.



The major advantage to this new thinking on ceramic fabrication is the combination of anode and electrolyte by extruding several of these two different materials at the same time (co-extrusion). Combined with the size reduction as the plastic materials are pushed through an extrusion die, it is possible to produce complex micro-scale features (microfabrication). In fact, a microfabrication by coextrusion process was developed to manufacture nearly complete tubular cells with electrolyte layers only 10-20 microns thick.*

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