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Eric Wachsman been working with solid oxide fuel cells for nearly three decades and not just on the science and technology side. Wachsman also closely follows and writes on governmental policies insofar as these policies affect the development and deployment of SOFCs.

In this video—an invited talk at the recent ICACC’13 (37th International Conference & Exposition on Advanced Ceramics and Composites in Daytona Beach)—Wachsman covers the ebbs and flows of the government’s interest in fuel cells, and suggests that SOFCs aren’t getting nearly the attention they deserve. While generally noting that SOFCs are an enabling technology that can cover a spectrum both of large and small-scale applications, he goes on to explain the technology has a key distinction: It is the only technology capable of addressing all six of the fundamental strategies delineated in the DOE’s First Quadrennial Technology Review:

• Vehicle Efficiency;
• Vehicle Electrification;
• Alternative Hydrocarbon Fuels;
• Building and Industrial Efficiency;
• Grid Modernization; and
• Clean Power.

Nevertheless, he notes, DOE has de-emphasized SOFC R&D work or pushed it aside in favor of a narrow set of PEM fuel cell applications. The bottom line is that that SOFC development lacks the funding and focus it deserves, regardless of whether the interest is on traditional fuel sources or ones based on a new hydrogen infrastructure. In particular, he argues for a shift in emphasis from stationary SOFC applications to low-temperature SOFCs in the transportation sector—something, he says, that is crucial if SOFC R&D funding is to survive.

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University of Maryland’s Eric Wachsman discussed the role of solid oxide fuel cells in a balanced national energy strategy to open the 10th International Symposium on SOFC: Materials, Science, and Technology. Credit: ACerS.

I am wrapping up my photoblogging with coverage of events during days 3 and 4 of the 2013 International Conference on Advanced Ceramics and Composites. Here are some of my photos from the final two days:

Credit: ACerS.

Credit: ACerS.

Credit: ACerS.

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Low-temperature SOFCs: (A) Functionally graded bismuth oxide (Electrolyte 1) / ceria (Electrolyte 2) can allow use of hydrocarbon fuels at the anode at reduced temperatures. (B) Estimation of power output with LT-SOFCs from a single cell to a module (upper) and schematic diagram of power requirements according to various applications (lower). Credit: E.D. Wachsman, K.T. Lee; Science.

We’ve all heard stories of college kids who drop out even though they are falling short of graduation by one or two classes. That’s what two of my best friends did despite good grades. With those two, boredom, vision (or lack thereof) and money were factors. One became a truck driver, and the other … well, he went on to invent Tofurky(!). However, aside from sheer audacity, it didn’t make any sense to me then that they would walk away from such an investment (even at 1970s tuition costs).

That’s the same point Eric Wachsman et al. made about the United State’s policy and apparently diminishing support for solid oxide fuel cell R&D in his recent paper in Energy & Environmental Science. Their EES piece mainly is a policy plea emphasizing the foolishness (my word, not theirs) iof Congress and the Administration if they withdraw support for SOFCs by yanking the funding plug for the Solid State Energy Conversion Alliance in the FY 2012 and 2013 budgets.

Their argument boils down to this:

• The US has an international strategic advantage of hydrocarbon-based fuels (coal, natural gas, etc.), which will continue to be used in the foreseeable future, plus an infrastructure for distributing those fuels.
• Fuel cells are the most efficient means to directly convert these fuels to usable electrical energy.
• US fuel cell research has made considerable progress in the past, and is on the cusp of a new generation of breakthroughs that make portable power, transportation and stationary (utility and combined heat and power) applications much closer.

The last point above has been made, however, for many years if not decades, and begs for elaboration if it is to be taken seriously.

And, take it seriously they do! In the latest issue of Science, he and Kang Taek Lee, both affiliated with the University of Maryland’s Clark School of Engineering, report on significant advancements in SOFC technology, particularly in regard to high power densities— approximately 2 watts per square centimeter—with low temperature SOFCs (≤650°C). This, according to University of Maryland news release, is the highest mark set to date in that temperature range. Wachsman and Lee even report on significant advancements for SOFCs operating ≤350°C.

Other groups have demonstrated energy densities of ~2 W/cm², but at higher temperatures (800°C) and only in button-sized units of yttria-stabilized zirconia, and these approaches have been plagued with interconnect and other problems as upscaling attempts have been made.

Wachsman and Lee have taken a different materials path, initally using a functionally graded ceria/bismuth oxide bilayered electrolyte “where the [gadolinium cerium oxide] layer on the anode (fuel) side protects the [erbia-stablized bismuth oxide] layer from decomposing while the ESB layer on the cathode (oxidant) side blocks the leakage current through the GDC layer because of its high transference number (ratio of ionic to total conductivity).”

They then worked to optimize the thickness and composition of the bilayered GDC/ESB arrangement. The 650°C power density breakthrough happened when they 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.”

Is 2 W/cm² significant? They note that the renowned Bloom Energy stationary SOFC units operate with only one-tenth this density. Moreover, Bloom’s units operate at approximately 900°C, a characteristic that brings a raft of other problems.

But, in a more practical sense, 2 W/cm^{2 b} brings a wide range of real-world applications much closer than previously expected. 2 W/cm² puts LT-SOFC’s power density, pound for pound, ahead of internal combustion engines; if specific energy is used as a yardstick, the LT-SOFC and IC are equivalent.

^“Thus,” the authors say, “because our LT-SOFC has essentially the same power and energy density as an IC engine, it could potentially transform the automotive sector as, for example, a range extender for plug-in hybrid electric vehicles operating on conventional fuels. The corresponding 10-kW stack would only be a small cube of 10 cm per edge.” As the illustration above indicates, the cells packaged in various stack and module combinations deliver a hefty power output range of 200 W to 100 kW.

These achievements alone argue for continued federal SOFC support, but Wachsman and Lee are frustrated because, they say, there is a huge amount of layer and electrode microstructure optimization ahead (including work that is currently underway and planned) that is starting to demonstrate feasible performance levels at the 350°C level, including the use of materials that have high tolerance for carbon coking and other problems that enter the picture at lower temperatures.

And, if operating temperatures drop to 350°C… then the ball really starts rolling with faster start-ups (think cars and trucks), and better-performing and less expensive interconnects and sealants that can be mass produced.

Going back to the issue of federal policy related to SOFC development, Wachsman suggests in the news release that a major problem is that fuel cells and hydrogen have been linked too closely. “There is a problem in the perception of the public and policy makers, and in the funding of our fuel cell programs, that hydrogen and fuel cells are linked. Hydrogen-based fuel cells are the technology that has gotten all of the press and as a result we’re still waiting for a future hydrogen infrastructure. Yes, fuel cells can run off hydrogen, but they don’t have to.”

But that misperception, he continues, “has turned fuel cells into a ‘future technology’ and has resulted in a drastic reduction in the funding of fuel cell research by the DOE in favor of developing electric cars, when in fact fuel cells can be used right now in many stationary and mobile applications, including centralized power distribution and power generation for homes, businesses, and industry.”

He and Lee concede in Science that SOFC technology “has not fully matured.” But, given recent progress and plans for advancing the R&D work, and given the US strategic resources, LT-SOFCs have bright future for highly efficient applications that range from portable power sources to industrial-scale units. They conclude by saying, “LT-SOFC should be a technology of choice for these applications as long as we are in a hydrocarbon-based energy infrastructure.

Wachsman’s and Lee’s paper in Science is “Lowering the Temperature of Solid Oxide Fuel Cells” (doi:10.1126/science.1204090).

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Credit: Wachsman et al.; Energy & Environmental Science.

No.

Will it anyway? Unfortunately, it looks that way, based on the DOE’s 2012 budget request (pdf), which hacks off 41 percent of total SOFC funding from the current year budget, and would leave support at 65 percent of what it had in 2010. Moreover, it would cut off funding for the Solid State Energy Conversion Alliance

The US policy of turning off its support for SOFC R&D seems to me to be a horrible and strategic error and I’d say that it’s time sound the alarm—but Eric Wachsman, Craig Marlowe and Kang Taek Lee beat me to it!

Wachsman et al. have a new paper in the Royal Society of Chemistry’s Energy & Environmental Science journal that politely and intelligently flays the logic behind a federal policy that abandons SECA and technical leadership in this field to other nations, such as Japan and Germany, despite the substantial progress that SECA has been shepherding. The three authors are affiliated with the University of Maryland’s Energy Research Center. Wachsman is a member of ACerS and also serves as editor of Ionics.

It probably comes as no surprise to people in the materials field that SOFCs have an enormous future. As the authors note, “SOFCs have the highest potential efficiency for the conversion of fuel to electricity,” and are extremely fuel-flexible.

The authors continue to build their initial premise, writing,

“Recent progress in lowering operating temperature and power density improvements have made SOFCs a unique energy technology platform that offers stunning potential for electrical generation in not only centralized, but distributed and even mobile applications. Lowering operating temperatures reduces manufacturing costs, vastly simplifies the integration of balance of plant components and enables thermal cycling. Improved thermal cycling capabilities of low-temperature SOFCs would allow them to also play an important role in load following applications such as non-base-load electricity generation and transportation.”

So why would DOE walk away from SOFC technology now? (It should be noted that the DOE would shift most if not all of its support to proton exchange membrane fuel cells, aimed mostly at the transportation sector.) Wachsman et al. are baffled for a number of reasons, some of which I will attempt to capture here.

First, they hold up one of DOE’s main policy-making documents, its “Quadrennial Technology Review,” and compare its priorities with SOFC technology’s ability to deliver (see chart above). For example, the DOE lays out separate basic energy strategies for the “stationary” and “transport” marketplaces. Deployment of clean energy, grid modernization and improved building/factory efficiency are mentioned for the former; deployment of alternative fuels, fleet electrification and improved vehicle efficiency are identified for the latter. Sounds good, so far, the authors say, so SOFCs would seem to be able to be an important part of achieving all six of these strategies, if not a superior choice to the alternatives. “[F]uel cells in general, and SOFCs in particular, can be used in the execution of every DOE strategy. With an additional requirement that the technology utilize existing fueling infrastructure, SOFCs stand out as a key cross-cutting technology solution,” they argue.

They then go on to make detailed analyses of how SOFCs would contribute to each strategy. For example, in regard to deploying clean energy, they present a cogent, US-specific set of reasons for maintaining SOFCs in our technology portfolio.

“Today, 50 percent of the US’s electricity is produced from coal and 20 percent from natural gas. Our large reserves, and current lack of economically competitive alternatives, suggest that a sizable portion of our future electricity will continue to be derived from these two sources. …If electricity production remains dependent upon coal and natural gas, the sustainable use of these fuels and environmental emission reduction goals both require that we utilize these resources with the highest possible efficiency. While natural gas turbine technology has made significant progress and has efficiencies around 50%, coal technology still lags. Utilizing synthetic gas (syngas) derived from coal, SOFCs have potential efficiencies rivaling those of natural gas turbines. While many set a goal to eliminate our use of coal and natural gas, prudence suggests we ensure that their use is as efficient as possible until that goal is achieved.”

To further drive their point home, Wachsman et al. provide chapter and verse details of the remarkable achievements SECA-led R&D projects have made in lower operating temperatures, increasing power density, increasing materials durabilities and lowering costs. Wide scale applications and unsubsidized market penetration may still be a decade or so off, but impressive and successful demonstration and tests have occurred in uses that include

• Utility-scale power generation (with nearly twice the fuel-to-electricity efficiency and half the levelized cost of electricity, compared to pulverized coal/carbon capture and sequestration systems);
• High-efficiency distributed generation/gas turbine hybrid systems for grid stability and reversible (hydrogen-producing) SOFCs for grid storage;
• Combined heat and power, and “trigeneration” (heating, cooling and power) systems with over 70 percent efficiencies;
• Polygeneration system that can convert conventional energy sources “into multiple energy products, e.g., liquid fuels and electricity;”
• Vehicular auxiliary power units that can provide parallel hybrid support for anything from efficient tractor-trailer refrigeration units to range-extenders for hybrid an plug-in hybrid electric vehicles.

In the lab, Wachsman et al. report that significant progress has been made, such as in “near quadrupling of power density [that] provides significant room for lowering SOFC operating temperature. Such temperatures dramatically expand applications and reduce cost, thus, fundamentally altering the fuel cell paradigm. LT-SOFCs provide the opportunity to obtain all of the anticipated fuel cell benefits without waiting for a H₂ infrastructure.”

Billions of dollars have already been sunk into SOFC research, development and deployment. The authors conclude with reminding the DOE and the administration what is in clear view, namely, “Around the globe, meaningful pilots and commercialization activities are expanding in the use of SOFC driven CHP. Abandoning, or even delaying, investments into this cross cutting technology just as it is becoming commercially viable are not in our short or long term interests.”

And, they go on to plead that protecting these investments and restoring funding will “provide clarity to the public and stakeholders regarding our fuel cell vision, facilitate a promising technology on the cusp of commercialization and maintain the critical mass of talent that has been assembled with SECA and other promising commercial interests.”

Makes sense to me. If it does to you, you might want to let the folks in Washington, DC know what you think.

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A group from the National Institute of Advanced Industrial Science and Technology and the Fine Ceramics Research Association in Nagoya, Japan, reported in a recent issue of Science about their results in studying the anodedesign and electrochemical performance for SOFCs, including a tiny tubular SOFC that might be useful in small electronics.

They prepared three types of 1.9 mm diameter X 5 mm microtubular cells with NiO-Sc-stabilized zirconia (ScSZ) and Ce-doped zirconia (10Sc1CeSZ) for the anode, 10Sc1CeSZ for the electrolyte, and (La, Sr)(Fe, Co)O (LSCF)-Gd–doped ceria (GDC) for the cathode, with an interlayer of GDC betweenthe cathode and the electrolyte. The three kinds of cells were prepared. Each had different cosintering temperatures of the anode/electrolyte and thus different anode microstructures. The porositiesof the anodes were 54, 47, and 37% for the cells before reduction.

The first cell had Ni particles that were less than 100 nm in size. The size of Ni particles in the other two cell types was greater than 500 nm.

For the first cell (smallest Ni particle size), the researchers, using wet H, achieved maximum power densities of 1.1 and 0.5 W/cm² at 600°C and 550°C, respectively, at a linear fuel velocity of 0.8 m/s.

In contrast, at 600°C, they found the maximum power densities of the other two to be 0.36 and 0.2 W/cm², respectively.

One factor they looked at is fuel velocity. They noticed that in the first cell - the one with the greatest anode porosity - gas diffusion improved by when linear fuel velocity increased. They also note that the influence of linear fuel velocity becomes greater for lower operating temperatures.

Technology Review asked two ACerS members for their reactions to this study. Eric Wachsman, director of the Florida Institute for Sustainable Energy and chair of materials science and engineering at the University of Florida cautioned that the operating temperatures, even in microtubular SOFCs, may still be too high and that their long warm-up time limits their suitability for consumer electronics like cell phones. However, other AIST research asserts that in the micro ceramic parts, “the thermal shock resistance of the cell has been dramatically enhanced, thus enabling the fabrication of compact SOFC modules that can be used in rapid startup and shutdown operations.”

Harry Tuller, professor of ceramics and electronic materials at MIT, was pleased by the performance of the Japanese fuel cells but he has concerns that doping the electrodes and electrolytes with small amounts of rare and expensive materials, such as scandium.

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