BC Hydro and S&C Electric Company partner on sodium-sulfur battery energy storage project
DOT may award $500K to SwRI for study on emissions from biodiesel-fueled locomotives

Modified SOFC anodes allow operation at lower temperatures with carbon-containing gases; potential for much more efficient and cleaner generation of electricity from coal

Terminal voltages measured at 750 °C as a function of time for the cells with (blue line) and without (red line) BaO/Ni interfaces operated at a constant current density of 500 mA cm-2 with wet CO (with ~3 v% H2O) as the fuel. Yang et al. Click to enlarge.

Using barium oxide nanoparticles, a team of researchers led by Georgia Tech has modified the surface of conventional anodes for solid oxide fuel cells (SOFCs) to enable operation at lower temperatures (750 °C) with carbon-containing gases—e.g., gasified coal—by eliminating the coking problem. The resulting lower-temperature SOFCs could provide a cleaner, more efficient alternative to conventional power plants for generating electricity from coal reserves. An open access paper on their work was published 21 June in the journal Nature Communications.

Conventional coal-fired electric generating facilities capture about a third of the energy available in the fuel they burn. SOFCs powered by gasified coal are about twice as efficient as current coal-fired power plants, potentially reducing CO2 emission by 50%, Yang et al. note in their paper. If gas turbines and SOFCs could be combined into hybrid systems, researchers believe they could capture as much as 80% of the energy. A significant barrier to SOFC implementation with gasified coal, however, is the vulnerability to coking (being rapidly deactivated via clogging with carbon deposits) of the Ni-YSZ (yttria-stabilized zirconia) anodes at temperatures below 850 °C, where SOFCs become more competitive economically.

For direct utilization of hydrocarbon fuels, a number of alternative anodes have been developed...However, the application of these anodes to actual fuel cell systems is hindered by several critical issues: they are either too expensive to be economically viable (for example, using a noble metal such as Ru or Pd) or outright incompatible with the current YSZ-based SOFCs systems, which have evolved progressively in the past few decades, because of the limited physical, chemical and thermal compatibility of the alternative anodes with YSZ electrolyte during fabrication at high temperatures.

...Although SOFCs powered by H2-rich syngas derived from steam gasification of carbon may be operated at lower temperatures, the required excess of water not only dilutes the fuel but also increases system complexity and cost because of the need for water management. To date, no stable and desirable power output has been demonstrated by SOFCs with Ni-YSZ-based anodes in CO or gasified carbon through CO2 gasification below 850 °C. The search for alternative anodes for direct utilization of CO at intermediate temperatures has progressed slowly and the existing SOFCs powered by CO and gasified carbon or coal are still inadequate for practical applications.

—Yang et al.

To counter this problem, the researchers used a vapor deposition process to apply barium oxide nanoparticles (NiO-BaO) to the nickel-YSZ electrode. A continuous BaO film would block the electron path in the anode; the particles, which range in size from 10 to 100 nanometers, form islands on the nickel that do not block the flow of electrons across the electrode surface.

“ We can continuously operate the fuel cell without the problem of carbon deposition.”
—Meilin Liu

When water vapor introduced into the coal gas stream contacts the barium oxide, it is adsorbed and dissociates into protons and hydroxide (OH) ions. The hydroxide ions move to the nickel surface, where they combine with the carbon atoms being deposited there, forming the intermediate COH. The COH then dissociates into carbon monoxide and hydrogen, which are oxidized to power the fuel cell, ultimately producing carbon dioxide and water. About half of the carbon dioxide is then recirculated back to gasify the coal to coal gas to continue the process.

Unlike alternative anode materials under investigation, the elemental composition of the new anode is very simple and contains no rare earth elements, which helps work towards true cost effectiveness, the researchers said. Moreover, the BaO treatment can be readily incorporated into existing processes for fabrication of advanced SOFCs based on YSZ electrolyte; it does not introduce additional processing steps—vapour deposition is implemented during the firing of the buffer layer—and there are no known compatibility issues that often arise with the use of other alternative anode materials occuring with the BaO, the team said.

This could ultimately be the cleanest, most efficient and cost-effective way of converting coal into electricity. And by providing an exhaust stream of pure carbon dioxide, this technique could also facilitate carbon sequestration without the separation and purification steps now required for conventional coal-burning power plants.

—Meilin Liu, a Regents professor in the School of Materials Science and Engineering at the Georgia Institute of Technology

The researchers also evaluated the use of propane to power solid oxide fuel cells using the new anode system. Because oxidation of the hydrogen in the propane produces water, no additional water vapor had to be added, and the system operated successfully for a period of time similar to the coal gas system.

Solid oxide fuel cells operate most efficiently at temperatures above 850 °C, and much less carbon is deposited at higher temperatures. However, those operating temperatures require fabrication from special materials that are expensive, and prevent solid oxide fuel cells from being cost-effective for many applications. However, reducing the operating temperature meant worsening the coking problem.

Fuel cells powered by coal gas still produce carbon dioxide, but in a much purer form than the stack gases leaving traditional coal-fired power plants. That would make capturing the carbon dioxide for sequestration less expensive by eliminating large-scale separation and purification steps, Liu noted.

The researchers have so far tested their process for 100 hours, and saw no evidence of carbon build-up. A major challenge ahead is to test the long-term durability of the system for fuel cells that are designed to operate for as long as five years. Researchers must also study the potential impact of possible fuel contaminants on the new electrode.

Forming the barium oxide structures can be done as part of conventional anode fabrication processes, and would not require additional steps. The anodes produced in the technique are compatible with standard solid oxide fuel cell systems that are already being developed for commercial electricity generation, home power generation and automotive applications.

We have started with state-of-the-art technology, and simply modified the surface of the electrode. Because our electrode would be built on existing technology, there is a lower barrier for implementing it in conventional fuel cell systems.

—Mingfei Liu, postdoc in the Center for Innovative Fuel Cell and Battery Technologies

The research was supported by the US Department of Energy’s Office of Basic Energy Sciences, through the HeteroFoaM Center, an Energy Frontier Research Center. The work also involved researchers from Brookhaven National Laboratory, the New Jersey Institute of Technology and Oak Ridge National Laboratory.


  • Lei Yang, YongMan Choi, Wentao Qin, Haiyan Chen, Kevin Blinn, Mingfei Liu, Ping Liu, Jianming Bai, Trevor A. Tyson & Meilin Liu (2011) Promotion of water-mediated carbon removal by nanostructured barium oxide/nickel interfaces in solid oxide fuel cells. Nature Communications 2, 357 doi: 10.1038/ncomms1359



Interest potential to convert coal to electricity more efficiently while producing less pollution. Can it be built rugged enough to operate for 2 or 3 decades without major maintenance?

It would even be better if the CO/CO2 produced could be converted to liquid fuels


There are several companies that make SOFCs with gas turbines at the output that claim over 70% efficiency now.
There is an SOFC company that makes a stack that will take hydrocarbons directly.

None of them will run for decades with no down time, but neither will a coal fired power plant. They could use some of the CO2 and electricity to make hydrocarbons, but it is probably easier to use some of that gasified coal in the first place.


Converting CO2 to fuel is costly in terms of used energy. Better to convert directly feed syngas or use electricity to charge batteries.
Do not make systems more complicated than absolutely necessary.


The SOFC uses H2 and CO as fuel and produces mostly H2O and CO2 as an output. The gas turbines use the remaining H2 that was not used with the hot expanding gases.

This seems like a very good idea. Santa Clara, California used a 2 MW SOFC array 20 years ago as a test. They did not use coal gas but natural gas, it was efficient but ahead of its time.


Lower temp SOFCs are a key to distributed CHP appliances in the home. The other key is the source of H2.

Stan Peterson


Isn't it a telling comment that the eco-loons who have taken control and now run the Sierra Club, routinely sue to impede the construction of all coal fired power palnts regardless of technology such as this.

The Sierra Club fools are oblivious to technological improvemnts, and condemn all coal plants indiscrimanently. Replacing an old, inefficient and grandfathered pollution generating coal power plant with one of these plants, is no different in their green clouded eyes, even as we sane people only view with disdain such fools.


When you use terms like that, you lose what little credibility you might have had.


Either way, it would be advantageous to find ways to use the world coal reserves without creating too (coal to wheel) much pollution.


Why not feed biofuel production with this system and recirculate it back at the input. That way we make biofuels and produce electricity and heat(hot water for heating in winter)from coal that not just act as an energy scource for electricity but as feedstock for biofuels too like green algae farming or methanol etc.
The future is systems with fuel recirculation for the production of energy needs and abuse too, because just think of corvettes and suv's and personnal motorcycles and watercrafts.


Looks like coal wants in on the distributed energy appliances that are on the way. Okay. IF coal can demonstrate a consistent policy of of environmental restoration - and a method of making efficient COH - fine.

But first generation SOFC's for home CHP will utilize existing infrastructure NG.

The comments to this entry are closed.