redox power feature

cube housingRedox envisions Cube SOFC units as ubiquitous appliances that could provide always-on power for homes and businesses. (Credit: Redox Power Systems.)

Nearly two years ago, in November 2011, Peter reported here on remarkable advances in ceramic materials for solid oxide fuel cells that resulted in very high energy densities at relatively low temperatures.

As reported by University of Maryland professor and ACerS Fellow Eric D. Wachsman and coworker Kang Taek Lee in the journal Science (“Lowering the Temperature of Solid Oxide Fuel Cells,” DOI:10.1126/science.1204090) and in CTT, the approach bypassed the yttria-stabilized zirconia used in other SOFC electrode designs in favor of a functionally graded ceria/bismuth oxide bilayered electrolyte. Work to optimize the thickness and composition of the bilayered material yielded breakthroughs in energy density and operating temperature when the researchers fabricated “an anode-supported cell composed of a thin, dense GDC (~10 μm)/ESB (~4 μm) bilayered electrolyte with a newly developed high-performance bismuth ruthenate-bismuth oxide (BRO7-ESB) composite cathode,” according to the Science paper.

Now the patented materials technology is set to make a commercial splash. UMD and Redox Power Systems LLC recently announced that they will work jointly to commercialize SOFCs using the technology.

Formed in early 2012, Redox has exclusive rights to Wachsman’s patents, according to the release. The company hopes to bring the technology to market at about one-tenth the cost of current commercial SOFC systems, and plans to build a prototype with an eye toward commercialization in 2014. The prototype unit is already under development, and Redox has been in contact with “numerous organizations asking us to test at their site,” Wachsman says in an email message.

Called the Redox PowerSERG 2-80 Cube (SERG for Secure, Efficient, and Reliable Generation; 2-80 for the device’s initial configurability to generate from 2 to 80 kW), the 750-lb unit is about one meter on a side. Specifications call for it to produce 2.5 W/cm2 at an operating temperature of 550°C.The unit’s energy density is roughly ten times that of other commercial SOFCs, and low-temperature operation—other commercial units operate at 800–900°C—improves reliability and service life and reduces costs by minimizing potential problems with interconnects, packaging materials, and other auxiliary systems that can occur at higher operating temperatures. The press release claims the system can achieve 80% efficiency when generating both heat and power.

The Cube initially will operate on natural gas converted to methane, but plans call for units fueled with biomass, propane, diesel, and JP-8. “Wholly self-contained units provide the ‘building blocks’ to create power systems of any size,” the product website says. The first units will be configured to produce 25 kW, enough power to run commercial establishments such as gas stations and strip malls. 

“Every business or home should be able to safely generate its own energy,” Redox CEO Warren Citrin says in the release. “We currently rely upon a vulnerable electrical grid. The best way to decrease that vulnerability is through distributed energy—that is, by making your own energy on-site. We are building systems to do that, with an emphasis on efficiency and affordability. These should be common appliances.”

According to the release, Wachsman began working with SOFC technology as a graduate student in the 1980s. “Over a 25-year time period, we have achieved major advances in both the composition of fuel cell materials and the micro- and nanostructure of those materials,” he says.“Putting these together has resulted in a cell that has an extremely high power density.”