The Red Brick Times

Teeny Tiny fuel cell. The size of a watch battery. It burns propane. Developed from work by Caltech, USC and Northwestern U in Illinois, the cell needs to generate enough internal heat to operate with hydrocarbon fuels. Add insulation, and it gets too big to put in your MP3 player. They solved it by controlled burning rates to keep temps up. Propane is liquid when compressed and vaporizes when released (think butane cigarette lighter as a fuel delivery example). So your watch battery will not need a carburetor (watchburetor?). See the Caltech news release titled "New Propane-Burning Fuel Cell Could Energize a Future Generation of Small Electrical Devices."

You can make your own room-temperature, ambient-pressure, "dissolved fuel" cell from common household materials, like an air cathode made from a nickel mesh with an applied manganese catalyst, on a carbon support, with a PTFE binder. It can be glued to almost all plastics using Loctite 406 instant adhesive, provided that the surface to be glued is treated with Loctite 757 primer. Also required is a fuel cell anode, made from nickel mesh with a platinum catalyst, on a carbon support, with a PTFE binder. Finally, the fuel can be methanol, ethanol or sodium borohydride (the last is the most efficient) dissolved in an alkaline electrolyte. See Electro-Chem-Technic to read and purchase materials.

On the large commercial front, an English company, Ceres Power , is pursuing larger and more powerful cells that can use commercially available fuels including LPG, alcohol, natural gas, hydrogen or vehicle fuels. Their focus is on solid oxide (SO) fuel cells ( as opposed to proton exchange membrane (PEM) fuel cells). They are trying to reduce the operating temperature and as a result, the startup lag time and the need for high-temp materials for construction. Metals are easier and cheaper to work than are ceramics for the internal bits, but metals tend to soften or melt at regular SO fuel cell temperatures.

Solid Oxide fuel cells (SOFC) are more tolerant of different fuel types. A big advantage is that both hydrogen and carbon monoxide are used in the cell. In the PEM or Polymer Electrolyte fuel cell (PEFC) the carbon monoxide is a poison, while in the SOFC it is a fuel. This means that the SOFC can readily use many common hydrocarbons fuels such as natural gas, diesel, gasoline, alcohol and coal gas. In the PEFC an external reformer is required to produce hydrogen gas while the SOFC can reform these fuels into hydrogen and carbon monoxide inside the cell. This results in some of the high temperature waste thermal energy being recycled back into the fuel (from Ben Wiens Energy Science: "The Future of Fuel Cells"; section 8. Solid Oxide Fuel Cells). See Ben Wiens Energy Science site for all things energy.

As an added benefit, a home-located fuel cell generator can also make hot water for washing up and for heating. Keep an eye on the Big-Box home improvement stores. When fuel cell home generators (propane or natural gas fueled) show up there, you know it is time to get on board.
Posted 11:01 AM by Andy (5) comments

       Comments:

Andy, I recall an exchange a while back wherein you were skeptical, in the extreme, of the feasibility of fuel cell technology. The reason cited had something to do with the high cost of obtaining hydrogen from natural gas and the attendant pollution that would render the exercise an environmental wash. Is it your current opinion that this new technology will side step those problems? Is the production and use of propane more efficient and less polluting in the long run? Will I be able to illuminate my house with a Bic lighter?

# posted by  A. O. : February 01, 2006 6:36 PM
 
No, I am still skeptical. Trouble looms on several fronts. Econonic - it still costs more resources and energy to produce hydrogen that it does to produce petrochemical hydrocarbons. Look at a report by NPR today about the total cost of ethanol production vs petrochemical:"Professor Attacks Enthusiasm for Bio-Fuels."
Political - entrenched interests are way over on the petro side with tiny little projects on renewable. Also, a huge part of our engineered materials (plastics, synthetics, composits) are based on the carbon-chain backbones from crude oil. I mean, when untold billions are pouring into the oil company banks, why change the direction? Technical - many steps and improvements are needed before you and I have a fuel cell on our wrists, or in our laptop, or even in the basement. I am looking at the slow progress of 90%-plus efficiency gas furnaces. I went to school for pulse boilers in 1985. Today, new installs are mostly 80% or greater efficiency forced air and hot water. But the maintenance and repair costs are triple that of the old technology (more controls, sensors, fans, plumbing). Also look at the progression of automotive fuel injection for average consumer vehicles. VW was the exception and had electronic fuel injection in the 1970s. It is common today, but the implementation was incremental, costs crept into the product, manufacturer and consumer resistance was slow to overcome. I see the same evolution for fuel cells. Off-grid will always be more expensive than on, and most useful in rural and remote areas. The most extreme off-grid is space. In the 1960s, the Apollo program had hand-built hydrogen-oxygen fuel cells to produce electricity and water. Over forty years later, we still don't have them commonly available. I don't see this technology as the immediate savior of the oil-hungry West.

# posted by  Andy : February 02, 2006 12:09 PM
 
OK, clears that up. What do you know about the co-generation front (i.e. capturing and reusing waste heat) or efforts to improve the energy extraction efficiency of current systems?

I've thought that encouraging the use of small electric commuter vehicles would help (versus single occupant SUV's), which it would in terms of fuel, but ultimately you end up with more vehicle mass/passenger causeing the savings to squirt out somewhere else. Efficient mass transit seems to be the answer. The reason one oil barge is more efficient than 800 tanker trucks applies to human cargo with the trade off being the inconvenience of having to actually participate in society.

# posted by  A. O. : February 02, 2006 1:40 PM
 
Co-Generation skins the cat more closely. For example - in the basement of the boiler house at Ohio University, where the main steam line exits to the rest of the campus, there is a throttling valve, designed to regulate the mass of steam sent down the pipe based on the line pressure and flow demand. It's a noisy thing, screaming like the damned as it lets some steam go down the pipe and diverts the rest back to the condensors. The University put a co-generation turbine at this point to take the "waste" steam and make electricity. It not only paid for itself, but for the multi-million dollar new substation they installed to handle the campus power flow. Savings in commercial power costs were purchased by tapping steam that they had already bought via coal and natural gas. It has always seemed to me to be a fractal division. Each potential difference in energy states might be used to do work. But as the differences get tinier and tinier, the costs increase and the returns vanish. Could you put a turbine wheel in your sewer pipe to capture the gravity flow of effluent? Yes, but you have to put up with potential breakdowns and backups. Most household waste is "gray water" from sinks and laundries and dishwashers. Only a few percent is "black water" from WCs. RVs use separate tanks. Home DWV plumbing (currently a Victorian-era design)would have to change to capture waste-stream energy.

The same visualization can be done for heat energy flowing through walls, for electric and mangnetic fields oscillating around the wires in your walls, and the wind pressure differential between the peak of your roof and the eaves.

# posted by  Andy : February 02, 2006 4:36 PM
 
Now that last picture woke me up. Amazing what an unfettered brain can do. I was visualizing the roof as an airplane wing. A duct installed between the high-pressure surface and the low pressure downstream side could easily drive an enclosed impeller. Now. How to keep the rain and snow and bird's nests out.... Oh well, the genius part is easy. The rest is simply engineering sweat.

# posted by  Andy : February 02, 2006 4:47 PM
 
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