Micro Fuel Cells

[don c.]

ALBANY, N.Y., Sept. 21 — Cell phones free from nightly recharges. Laptop computers that run and run without needing an outlet. Pocket TVs with enough power to show a Ken Burns documentary. Portable gadgets are demanding more and more juice. A viable alternative to rechargeable batteries isn’t here yet, but when it comes, it might work like the device about the size and weight of a deck of cards in William Acker’s hand. It’s a micro fuel cell.

Micro fuel cells are expected to get smaller. In the long run, just about anywhere where high-end batteries are the right answer, these devices should be a better answer (my emphasis), Acker said. Micro fuel cells are supposed to have several advantages over rechargeable batteries. Once fully developed, micro fuel cells should last 10 times as long as the current generation of batteries, Acker said. And no more recharges. When a fuel cell runs out of methanol, just snap on a replacement fuel cartridge. Also, fuel cells can provide more power. The potential for a lucrative market has drawn a mix of start-ups and big names. Nash cites Motorola, Toshiba and Casio, which has developed a fuel cell it intends to sell commercially in 2004.

Smart Fuel Cell, a German company, recently introduced a device fueled by a 2.5 liter methanol cartridge that can be used with outdoor equipment.

more at: http://www.msnbc.com/news/810641.asp

[Seeker]

I'm sure 'micro' fuel cells , will catch on in a 'big way' !

As with all developing technologies, they have some issues to work through, and it sounds like heat removal is one of them.

"The challenges facing micro fuel cells in order for commercialisation to take place - Heat removal, system power requirements, efficiency, miniaturization, methanol cross over."

http://www.eyeforfuelcells.com/events/boston2002/


If you don't mind lugging around a briefcase sized stirling, this might help with the heat removal :

" Kamen hopes that his family of Stirlings, five years in development, will soon bring portable electricity to nations without a reliable power grid - or any grid at all. He envisions briefcase-sized Stirlings powering cell phones and cell towers, as well as purifying water. He aims to have them on the market in the next two years, and is currently working on the marketing issues "

http://www.wired.com/wired/archive/8.09/kamen_pr.html

Seeker

[ftropea]

Ok, but the question is...

Would a micro-Stirling be more/less efficient in terms of power production -vs- fuel consumption than a micro-fuel cell?

Regards,

Frank A. Tropea

EDIT: Clarified my poorly worded question.

[Seeker]

quote:Originally posted by ftropea

Ok, but the question is...

Would a micro-Stirling be more/less efficient in terms of power consumption than a micro-fuel cell?

Regards,

Frank A. Tropea

Hi Frank,

Since excess heat production is one of the problems to overcome with micro fuel cells, I was thinking you could couple the fuel cell & stirling together. So you would use the excess heat from the fuel cell, to power the Stirling.

But then again this would add to the weight,and size of the power generation system, and also to the cost of it.

Seeker

[ftropea]

This is one thing I've always wondered about... The idea of just plugging Stirlings wherever you have excess heat. I once proposed a sort of nanotechnological approach to utilizing the Stirling engine. Imagine tiny Stirling engines.. the cylinder a ring of atoms.. the piston made of some magnetic material. The outside of the cylinder is wrapped in a coil of copper atoms... as the working gas/atoms is being displaced, the magnetic piston moves up and down... The magnetic field interacts with the copper coil, producing electricity.

Now imagine millions of these nano-stirlings mixed with another conductive subtance - in the form of a "paint" and that this paint is applied to a surface.. This surface is conductive on one side and insulated on the other. The non-conductive side is bonded to a heat producing source, say the exterior of your car engine.. the conductive surface is connected to "leads" which pull the electrons away into a battery/capacitor...

The conductive surface is layered in an protective laminate.. protection from water.. scratches.. etc...

Just an idea floating in my mind...

Regards,

Frank A. Tropea

EDIT: The cylinder itself could be the copper coil... capped at either end. That might be simpler...

[ftropea]

The idea of using the magnetic piston and copper coil is to simplify the electric production aspect of the Stirling.. no external generator needed.. or flywheel... don't know if it works theoretically, but I'm thinking nano-tech.. so maybe it could work. Trying to keep it simple..

Regards,

Frank A. Tropea

[Seeker]

################

[yop]

Efficiency:
The theoretical efficiency of a Stirling is 50%; the theoretical efficiency of a fuel cell is close to 100%. So once they manage to build a "good" fuel cell, I would expect it to be more efficient than a Stirling at converting the energy in its fuel to electrical power.

The Stirling does have a big advantage in its choice of fuel, however. Fuel cells need extremely pure, high grade fuel: hydrogen and methanol are the two that I've heard the most about. The Stirling, on the other hand, just needs a source of heat; from burning wood, coal or oil, from concentrated solar energy, from anything. There's never going to be a wood-powered fuel cell. You could take the wood, convert it to methanol, and use that to power your fuel cell. It could potentially still be more efficient than the Stirling, but you'd need to spend a lot to buy the refining and distribution equipment.

Micro Stirling engines:
A Stirling engine requires a temperature differential. I think it would be difficult to maintain this temperature difference across a really short distance. Heat insulation isn't good enough.

[Seeker]

quote:Originally posted by ftropea

This is one thing I've always wondered about... The idea of just plugging Stirlings wherever you have excess heat. I once proposed a sort of nanotechnological approach to utilizing the Stirling engine. Imagine tiny Stirling engines.. the cylinder a ring of atoms.. the piston made of some magnetic material. The outside of the cylinder is wrapped in a coil of copper atoms... as the working gas/atoms is being displaced, the magnetic piston moves up and down... The magnetic field interacts with the copper coil, producing electricity.

Now imagine millions of these nano-stirlings mixed with another conductive subtance - in the form of a "paint" and that this paint is applied to a surface.. This surface is conductive on one side and insulated on the other. The non-conductive side is bonded to a heat producing source, say the exterior of your car engine.. the conductive surface is connected to "leads" which pull the electrons away into a battery/capacitor...

The conductive surface is layered in an protective laminate.. protection from water.. scratches.. etc...

Just an idea floating in my mind...

Regards,

Frank A. Tropea

Hi Frank,

That idea sounds fasinating. Myself, I don’t know a whole lot about nanotechnology. The only thing I would wonder about is the heat loss effects you would experience at small sizes. You know like,as the size gets smaller, the surface area becomes larger, relative to the volume, and heat loss is proportional to surface area. But then this may be really only a factor if you’re comparing the heat loss of a large object to that of a smaller one. So it seems to me that if this kind of thing could be done cost effectively then it could be promising.

Another thing I wonder about is thermcouples. Don’t they have the ability to change heat into electricity ? Couldn’t they be used to convert the waste heat energy produced by devices such as computers etc, into electrical energy ? I’m thinking there must be some energy storage issues and cost issues that would come into play.

Seeker

[Seeker]

Relating to the idea of using the ‘thermocouple effect’ to change waste heat energy into electrical energy, I’ve posted some info and a link below :

Ya know... it seems like everyone is always working on valuable research projects , but it takes a long time to get a new technology to the point where it becomes useful. Don’t get me wrong, I know they’re trying their best, and probably making new advances all the time.

I guess that’s why 2 summers of research was enough for me.... :-)

Seeker



http://www.globaltechnoscan.com/31ja...generators.htm

quote:
The School of Engineering at Cardiff University has been conducting research into the conversion of heat energy into electrical power by means of the Seebeck effect. In principle, this involves utilising the properties of the thermocouple, which consists of two electrical conductors of different materials joined together at both ends. If the junctions are kept at different temperatures, an electric current is generated and flows through the conductors.

quote:
By linking together a large number of modern semi-conductor thermocouples in series, a sizeable current can be generated without any moving parts. For example, spacecraft like NASA’s Voyager deep- space probes rely on thermoelectric generators to provide all their on-board electrical power, and these devices were still performing to specification more than 14 years after launch and after a journey of more than a bullion miles.

quote:
Researchers have been wording on improving the efficiency of these devices, and reducing the cost of making them, to employ them over a wider range of applications. The first stage involved a detailed study of the materials used, to maximise the electricity output for a given heat source. Work was also done on the design and construction of thermoelectric generators to maximise their output and on the long-term behaviour of the materials, to predict their reliability.
Attention has also been turned to cheaper ways of making the materials used in thermoelectric generators, with the investigation of techniques like hot pressing, mechanical alloying and the deposition of materials from aqueous solutions. The overall objective is to develop devices which can produce useful amounts of electrical energy from low-temperature waste heat, which is otherwise very difficult to exploit as common by-product of many industrial processes.