“COOL” FUEL CELLS COULD REVOLUTIONIZE EARTH’S ENERGY RESOURC

crossthread · Heavy Crude Joined: Jun 20, 2004 Posts: 179

http://www.uh.edu/admin/media/nr/2004/07july/072204fuelcells.html

HOUSTON, July 22, 2004 – As temperatures soar this summer, so do electric bills. Researchers at the University of Houston are striving toward decreasing those costs with the next revolution in power generation.

Imagine a power source so small, yet so efficient, that it could make cumbersome power plants virtually obsolete while lowering your electric bill. A breakthrough in thin film solid oxide fuel cells (SOFCs) is currently being refined in labs at the University of Houston, making that dream a reality.

Originating from research at UH’s Texas Center for Superconductivity and Advanced Materials (TcSAM), these SOFCs of the “thin film” variety are both efficient and compact. With potential ranging from use in the government in matters of defense and space travel to driving forces in the consumer market that include computers and electricity, this breakthrough carries tremendous impact.

“By using materials science concepts developed in our superconductivity research and materials processing concepts in our semiconductor research, we are able to reduce operating temperatures, eliminate steps and use less expensive materials that will potentially revolutionize from where we derive electrical energy,” said Alex Ignatiev, director of TcSAM and distinguished university professor of physics, chemistry and electrical and computer engineering at UH. “While there are a number of fuel cell research programs at the university, ours focuses on the application of thin film science and technology to gain the benefits of efficiency and low cost.”

Compared to the macroscopic size of traditional fuel cells that can take up an entire room, thin film SOFCs are one micron thick – the equivalent of about one-hundredth of a human hair. Putting this into perspective, the size equivalent of four sugar cubes would produce 80 watts – more than enough to operate a laptop computer, eliminating clunky batteries and giving you hours more juice in your laptop. By the same token, approximately two cans’ worth of soda would produce more than five kilowatts, enough to power a typical household.

Keeping in mind that one thin film SOFC is just a fraction of the size of a human hair with an output of 0.8 to 0.9 Volts, a stack of 100 to 120 of these fuel cells would generate about 100 volts. When connected to a homeowner’s natural gas line, the stack would provide the needed electrical energy to run the household at an efficiency of approximately 65 percent. This would be a twofold increase over power plants today, as they operate at 30 to 35 percent efficiency. Stand-alone household fuel cell units could form the basis for a new ‘distributed power’ system. In this concept, energy not used by the household would be fed back into a main grid, resulting in a credit to the user’s account, while overages would similarly receive extra energy from that grid and be charged accordingly.

“The initial applications of our thin film fuel cell would probably be for governmental entities,” Ignatiev said. “For instance, once the preliminary data satisfies the Department of Defense, we could see our fuel cell research in action in the backpacks of soldiers, replacing heavy batteries to power their computers and night vision goggles and such.

“NASA also is very interested in this research mainly because of the weight and size factors,” he said. “Thin film SOFCs offer light, compact, low mass properties of significant interest to them. Right now, the shuttle routinely uses fuel cells that require ultrapure oxygen and hydrogen, use exotic materials and are massive and large. But the thin film SOFCs we are developing at UH are not as sensitive to contaminants and are highly efficient in their design and lightweight size, which is ideal for space applications.”

Inherent to the more efficient design of these “cool” fuel cells is quite literally the fact that they operate at a much lower temperature than other solid oxide fuel cells, yet do not need a catalyst. Despite their 60 to 70 percent efficiency, SOFCs, in general, operate at 900 to 1,000 degrees Celsius, a very high temperature that requires exotic structural materials and significant thermal insulation. However, the thin film solid oxide fuel cell has an operating temperature of 450 to 500 degrees Celsius, one half that of current SOFCs. This lower temperature is largely a result of the drastically decreased thickness of the electrolyte-working region of these thin film SOFCs and negates the need for exotic structural materials and extensive insulation. The lower temperature also eliminates the need for catalysts (known as reformers) for the fuel cell. All of these features indicate a reduced cost for the thin film SOFC and positive future impact on the fuel cell market.

Ignatiev anticipates that what he and his colleagues have been developing in UH’s TcSAM laboratories will advance to the testing phase within the next six months. The collaborative test bed for this thin film SOFC testing is the Houston Advanced Research Center’s Center for Fuel Cell Research and Applications.

Keis · Coal Joined: May 21, 2004 Posts: 12

Now this would be nice!

sidoze · Tar Sands Joined: May 28, 2004 Posts: 24

Looks neat but it sounds like they run on natural gas? Gas piped straight to the home is what its saying right?

But why go decentralized, if most power plants are 35% efficient and these are very efficient why not save on the transport costs and build a large array of these cool cells in some facility. I'm sure the transport of fuel to end users should be considered in the efficiency of the concept.

nero · Posted: Sat Aug 21, 2004 12:08 am Post subject:

450oC is really cool! If they have that going well there is some real hope for distributed power.

Distributed power has the added benefit of enabling the waste heat to be used on site for hot water or heating. This results in really incredible total energy efficiencies. Another benefit to distributed power as the early adopter for this technology is that a power plant has to plan for at least a 25 year life with very high reliability. It is very costly for radically new technology to spend the time and money proving itself with prototype demonstrations. Smaller scale situations where it is not mission critical if it fails would be ideal.

They are developing SOFC fuel cells for small power plants. Seimens are in the lead in this department I believe. What they hope to do is use the fule cell in combination with a turbine to achieve the best electrical efficiencies around. I haven't heard too much about their progress lately but they are past the prototype stage and are taking commercial orders.

Devil · Posted: Sat Aug 21, 2004 1:16 am Post subject:

And what happens to the CO2? Even so, what scares me with natural gas fuel cells is that there has to be an excess of fuel. This means there could be an emission of CH4 which is 25-75 times worse than CO2 as a GHG.

I agree with Sidoze that it is a lot easier and cheaper to distribute electricity than gas, therefore centralised generation would be more cost-effective and, probably, efficient, because it would be easier to have more complex and costly optimising controls in a large installation than in a small, household-size, one. Also, a large one could have better emission controls with useful post-combustion.

If this idea works at hundreds of °C, where does the energy come from for heating the cells?

Does the cited 60-65% efficiency last throughout the cell's useful lifetime or does the efficiency drop as the contaminants in the natural gas (which is not pure CH4) clog the cells? What is the cell's lifetime?

What are realistic capital, running and maintenance costs?

I'm not naysaying but I'm asking a lot of questions that must be asked before being able to judge the viability of the process.
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Devil

MarkR · Posted: Sat Aug 21, 2004 2:38 am Post subject:

Well, the CO2 is a waste product, and has to be disposed of in the same way as if you were burning the gas conventionally i.e. sinking to the atmosphere, or some form of sequestration.

The cells have to be heated first to get them going, thereafter the cells generate heat due to their inefficiency. In small cells (a few kW) their self heating is not sufficient, and additional heaters are required (probably gas burneres). However, in huge cells (thousands of kW) so much heat is generated that the cells need to be cooled.

Cooling is not a bad thing - the high temperature coolant can be effectively utilised e.g. it could drive a turbine for production of additional electricity (bringing efficiency at the grid connection to 70% or more) and the waste heat from the turbine could then be used for a community heating system.

As I understand it, the presence of hydrogen and other hydrocarbon contaminants in the NG is not much of a problem for the fuel cells. However, sulphur is, and gas purifiers are required to prevent damage to the cells.

The lifetime of SOFCs is not well defined yet - conventional high temp protypes have operated for over 20k hours, and still seem to be going strong. Some groups seem to expect 'up to 40,000 hours' from the newer low temp SOFCs. One particular problem seems to be migration of dopant ions through the various components - apparently this is a major problem because many of these are highly toxic. Additionaly, as traces of contaminants can seriously impair the cells, recycling of the used materials is impractical - it's much less energy intensive to use virgin material to fabricate new cells.

Pricing is difficult to predict. SOFC systems have been built in recent years at costs of around $4/W. For a system constructed today, you'd probablly end up paying about $1-$1.5/W.

However, several companies plan to start selling small scale SOFC systems within the next 2-3 years with estimated capital costs of around $0.80/W. Some speculate that by 2015 price could have fallen to about $0.20/W.

I am not able to comment on whether those prices are realistic - however, I am certain that they are very optimistic. Fuel costs are likely to be the dominant running cost - and this, of course, depends on the volatile nature of NG.

Just for reference, estimated new constructions costs for CCGT plant are about $0.8/W, new nuclear (advanced CANDU) about $1.1/W, and clean coal (integrated gasification) about $1.5/W. If construction costs could be made less than conventional CCGT, then their higher efficiency could make this technology viable. We will have to wait to find out.

k_semler · Posted: Sat Aug 21, 2004 3:01 am Post subject:

MarkR · Posted: Sat Aug 21, 2004 3:10 am Post subject:

k_semler · Posted: Sun Aug 22, 2004 12:42 am Post subject: