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Ceramic fuel cells could be the future of green, at-home power and heat generation

While interest in so-called “smart grids” is up in recent years, some researchers and public infrastructure experts have gotten to thinking beyond the grid. Local power generation inside your home has the potential to be highly efficient and perfectly responsive to demand, which is everything you want out of a traditional electric grid. Of course, this concept is not without its issues, most notably how you generate the power. A team of engineers from the famed Fraunhofer Institute has developed a super-efficient ceramic fuel cell that can be used in the home to generate both electricity and heat from natural gas.

Photo of the Remarkables mountain range in Queenstown, New Zealand.

When electricity is generated at a centralized power plant and distributed across a grid, that’s it — the electrons exist and need to be used in short order to maintain any semblance of overall efficiency. This isn’t going to change without a major advance in battery technology. A fuel cell based on natural gas, however, only produces as much power as your home/office needs, but the cost of these devices has long been a problem. Fuel cell cars are famously expensive, for example.

So if we just need to produce power locally, why not simply use an inexpensive generator? While generator technology is well-developed at this point, it’s not as efficient as a fuel cell. A generator takes a hydrocarbon energy source and converts that chemical energy to thermal energy (combustion), then it turns that into mechanical energy to drive the generator. You get electricity at the end, but some of the energy bleeds out in the process. A fuel cell takes the energy source (natural gas in this case) and uses steam reforming to break it down into a hydrogen-rich gas. Then oxygen ions undergo electrochemical oxidation with the hydrogen atoms at the anode to produce electricity with very little loss.

Fuel Cell

Much of the cost of a fuel cell comes in the choice of anode material. Platinum is used in many fuel cells, but the Fraunhofer Institute researchers used a ceramic material as the anode in this solid oxide (i.e. ceramic) fuel cell (SOFC). A solid fuel cell is less expensive and easier to produce than the proton exchange membrane fuel (PEMFC) cells being explored for use in automobiles. The trade-off, however, is that SOFCs produce a huge amount more heat — up to 850 degrees Celsius, which is ten times what is produced by PEMFC. Luckily, ceramics can take the heat.

To cope with the heat issue, the team is basically saying, “Hey, this fuel cell is your furnace now too.” Conveniently, the final product is about the size of a traditional furnace, but it pumps out both heat and power. The fuel cell itself is the about the size of a stack of CDs. At times when heat is needed, the fuel cell can provide enough of it to keep a home toasty, but when the weather is more pleasant, that excess heat has to be exhausted someplace (preferably outside). The energy output is more in-line with expectations, though. When running at peak efficiency, the prototype SOFC developed by Fraunhofer can produce one kilowatt. That’s enough to meet the need of an average four-person household. [Read: Fusion power at home, or, how small science will defeat big science.]

The Fraunhofer Institute has worked with heater manufacturer Vaillant to create a test version of this stacked fuel cell that can be safely mounted to a wall. A number of these units have been installed into private homes to evaluate performance in real life with 150 total consumer tests planned for this year.

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