New Generation of Hydrogen Fuel Cells Powers Up

An anonymous reader writes "A safer and more practical way of storing and releasing hydrogen, discovered by two Arizona State University researchers, could lead to a new type of fuel cell capable of packing 10 times more energy. The key is apparently using the alkaline compound borohydride — 'a 30% solution of borohydride in water actually contains one-third more hydrogen than the same volume of liquid hydrogen.'"

Chemical info on Borohydride

[xmas2003]

Wiki has a decent write up on NaBH4 [wikipedia.org] for those interested and mentions the applicability to Fuel Cells.

This is still in the research/development phase as per the article "Dr. Gervasio recognises that there are still many steps between his prototype and a competitively priced, off-the-shelf, battery-sized fuel cell. Nevertheless, he believes they could appear in power-hungry devices such as laptops, camcorders, and radios within five years." So until then, I'll be using CnH2n+2 to mow my lawn. [watching-grass-grow.com]

Re:Chemical info on Borohydride

[palapa]

Anhydrous ammonia has a hydrogen density of 0.12 gm/cm^3, compared to liquid hydrogen with a density of 0.07 gm/cm^3. In addition, ammonia is easy to reform for use in a fuel cell. Ammonia is already heavily distributed for agriculture, it volatilizes off as a lighter than air gas, it contains no carbon, and finding leaks is easy! The down side to either hydrogen-boride or ammonia is that they're not energy sources in themselves, but function (like a battery) as a convenient way to store energy.

Re:Huh? Help out an under educated ignorant, pleas

[Corp186]

Although I am not familiar with the chemistry of this research, it is quite possible to pack inordinate amounts of compounds in a solution. For instance, 1 ml (1 g) of water can hold 99 g of the compound used to develop film. The space around molecules in a solution can vary quite a bit, and if the geometries of the solute and solvent match very well to the forces between them, the wasted space can be decreased, increasing the concentration of the solution.

Re:Huh? Help out an under educated ignorant, pleas

[LotsOfPhil]

Liquid H2 is not very dense at all. It's density is .068 g/mL (compared to water, which is 1 g/mL). When the borohydride is added to water, you get NaBO2 and 4 H2 molecules.

Re:Huh? Help out an under educated ignorant, pleas

[Your Pal Dave]

They're probably figuring it on a volumetric basis. Liquid hydrogen is not very dense (71 g/l). I would imagine this solution would be greater than water (1000 g/l). In a mobile application the volume of the fuel would be very important, and storing LH2 is non-trivial due to the temperatures and pressures involved.

Re:Huh? Help out an under educated ignorant, pleas

[Anonymous Coward]

Liquid Hydrogen is not very dense. The attractive forces that pull it together to form a liquid are weak and only effective a low temperatures. When hydrogen forms molecules its electron tends to migrate towards other atoms slightly increasing the size of that atom's electron shells. A hydrogen atom shrinks right down to its nucleus, not the next smaller shell, since there are no other elcetrons to form shells when it loses its elctron. It takes 779 ml of liquid oxygen and 1586 ml of liquid hydrogen to make a liter of water. Hydrogen is a special case, even with inner shells left, binding forces can lead to higher densities. A liter of Aluminum oxide weighs 3.973 kg of which 1.905 kg is Oxygen. That same 1.905kg of oxygen in liquid form occupies a volume of 1.671 liters.

Re:NaBO2 - Is it dangerous?

[timatcrn]

How difficult is NaBO2 to deal with, and can it be dangerous/toxic?

From Batteries Digest [batteriesdigest.com]:

The only other reaction product, sodium metaborate (analogous to borax), is water-soluble and environmentally benign.

Re:Chemical info on Borohydride

[Smidge204]

Diesel fuel has a hydrogen density of about 0.23 gm/cm^3, is a stable liquid at room temperature, and is noncorrosive (both Sodium Borohydride and Ammonia are corrosive). Biodiesel is roughly the same properties with the added benefit of being sulphur-free, cleaner burning (it's a naturally "oxygenated" fuel), biodegradable and renewable.

The best, though, is that you can use any mixture of the two in existing vehicles with zero modifications* using the existing fuel storage, distribution and dispensing infrastructure.

(* Rich Biodiesel blends may require additives or fuel preheaters for cold weather climates to prevent clouding.)
=Smidge=

Re:Chemical info on Borohydride

[Rei]

The only energy source there is for our planet is the sun. All other fuels are essentially batteries there is only a difference as to when it was charged.

Now if you'll excuse me, I'm going to go use some more electricity that was pushed onto the wires by the local power plant that runs on solar-powered uranium.

Re:Chemical info on Borohydride

[AtomicBomb]

On the other hand, if you are talking about fuel cell for laptop, you don't really want to use anhydrous ammonia. It is damned lethal esp in confined space (read: in aircraft)... Many people seem to overlook the danger of ammnonia because they've handled diluted (5-10%) ammnonia solution at home. But, in gaseous form, it is even more toxic than carbon monoxide. The concentration that is Immediately Dangerous to Life and Health (IDLH) for ammmonia is 500ppm [cdc.gov] whereas it is 1200ppm [cdc.gov] for carbon monoxide.

The smell of ammonia is a good warning. However, it does not always mean you can run away quickly... Once upon a time, I was almost choked by a small amount of ammonia when I spent my summer working in an industrial control lab. Some guy tripped the fuse when I was working in the fume hood. I inhaled the stream of ammonia released by the reaction before realising that. I could barely speak for almost five minutes afterwards.

Re:Yaya...but it causes cancer

[Burz]

...well, at least it was cute and rhymed.

http://www.eere.energy.gov/vehiclesandfuels/pdfs/b asics/jtb_biodiesel.pdf [energy.gov]

"biodiesel can reduce the carcinogenic properties of diesel fuel by 94%"

Biodiesel exhaust != Diesel exhaust.