Digging Deep Case Study: Clamshell Furnaces Help Determine Feasibility of Geothermic Fuel Cells
Clamshell furnaces are helping researchers explore the potential for goethermic fuel cells.
Neal Sullivan is no stranger to challenging projects. As director of the Colorado Fuel Cell Center (CFCC) at the Colorado School of Mines, Sullivan oversees research on solid oxide fuel cells (SOFCs), polymer-electrolyte membranes (PEMs), advanced materials, and much more. It’s safe to say he’s tackling innovative solutions every day.
As is generally well known, fuel cells are used to generate electricity more efficiently than traditional methods. The CFCC works to further improve SOFCs by studying the materials and processing used to produce them, as well as their overall commercial viability. But one of the CFCC’s current projects involves a unique and challenging application: geothermic fuel cells.
The Geothermic Concept
The logical question is, “Why would anyone want to bury a fuel cell in the ground?” While potentially groundbreaking (no pun intended), the answer is really quite simple: oil.
“Fuel cells run at very high temperature,” explains Sullivan. “The objective in the geothermic fuel cell project is to harness that high-temperature operation to heat up the ground in which there are large deposits of oil shale, and turn that oil shale into oil. If you can get oil shale hot enough, the oil will liberate itself from that oil shale and then you can pump the oil out of the ground like you normally would. That’s compared to fracking, where you’re pushing high-pressure water or other substances under the ground. This is essentially heating the ground, cooking the oil shale, turning that oil shale into oil and pumping it out.”
With a 6-ft-long geothermic fuel cell manufactured by Delphi on behalf of Independent Energy Partners (IEP), Sullivan’s team is providing third-party testing and developing computational models focused on predicting performance. “No one’s ever placed a fuel cell in the ground before, so there’s a lot to learn,” he says.
Work in the Lab
The researchers need to understand how the fuel cell will operate in underground conditions before actually placing it in the ground. Key tools in the CFCC arsenal are three 4-ft clamshell furnaces manufactured by Deltech Inc., which was awarded the project through a state-mandated bid process.
“A number of bids were delivered, and Deltech’s matched the technical and cost targets the best,” says Sullivan. “We have a number of their furnaces in our laboratories already to do ceramic processing work, so we’re familiar with the technology and the Deltech team.”
Clamshell furnaces are ideal for this application because they enable access along the entire length of the furnace chamber. “If you don’t have a clamshell, you have to do everything from the two ends,” explains J.J. Stevenson, Deltech’s engineering manager. “The clamshell allows you to open up the entire furnace, build something inside it and close the furnace around it.”
The length of the fuel cell was also an important factor to consider for this application. “You would need a high ceiling if you wanted to put a long tubular fuel cell in from the top, and then connect it and do everything else,” says Stevenson. “If you have a clamshell, you can open all three spaces up, roll your tubular heater in, make all your connections and then close the clamshell furnace around it.”
Having the three 4-ft furnaces also offers a great deal of flexibility; each of the furnaces can be used alone, or they can be connected to each other to create a single 8-ft (with two of the furnaces) or 12-ft (with all three furnaces) heating zone. Deltech customized each furnace with removable end caps that provide insulation when the CFCC uses the furnaces on their own.
Each furnace is equipped with three-zone control. When operated alone, the furnaces feature a 6-in. entry zone, a 36-in.-long uniform heating zone, and a 6-in. end/cooling zone. When grouped together, the zones can be adjusted to operate as if they were in a single furnace. “If you envision the three furnaces on top of one another, the top zone in the top furnace is used as the entry and the bottom zone of the bottom furnace is used as the cooling zone,” explains Stevenson. “Basically, there is about 11 ft in between that is all uniform.”
Sullivan’s group is extending the length of the fuel cell to 8 ft in the laboratory and using two of the clamshell furnaces to achieve an 8-ft heating zone. The third furnace is being used to preheat gases that are fed to the fuel cell.
Temperature is a key factor for fuel cell performance, and Sullivan’s team is using the clamshell furnaces to help the geothermic cell reach optimum temperature. “We’re putting the fuel cell in the ground, but we’re not certain how it’ll perform there,” he says. “We’re trying to bring it up to speed in an environment that’s more controlled. To do that, we encased the fuel cell in a furnace and will bring it up to temperature using the furnace. These fuel cells run at 700-800°C—that’s pretty darn hot. We have some strategies planned to go from room temperature to that temperature, but we don’t want to jump right into it right now. We’d rather have some furnace support.”
Predicting performance in the underground environment is an important task for the research team; the furnaces will come into play here as well. “The furnaces have a wide range of operations, so we can use them to simulate ground environments,” says Sullivan. “The ground is going to help act as an insulator, to keep all of the heat in the fuel cells. Many times, we’re trying to liberate heat from the fuel cell to keep it from overheating itself, so there are concerns that we’re going to burn the fuel cell up while it’s in the ground. We can predict its performance in the ground by ‘faking’ the environment with these furnaces from Deltech.”
The Next Step
After all of the testing has been done, the models run and the predictions recorded, the next big step will be to bury the fuel cell in the ground and see how it performs when actually tasked with heating the oil shale. “This time next year, we should have one operating on this campus, in the ground,” says Sullivan. “It’s exciting stuff.”