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New Way to Make Hydrogen
zymano writes "Hydrogen is expensive to make and difficult to store. The most common way in making hydrogen is electrolyzing pure water. A new startup is trying a new way to make hydrogen. The process uses sodium which industry shuns because it generates sparks and heat when mixed with water. Signa has devised a way to mix sodium with silica gel or crystalline silicon to create a powder that essentially strips electrons from the sodium molecules in advance and stores them. When water is introduced, the chemical reaction proceeds calmly. The powder generates hydrogen efficiently. More than 9 percent of a kilogram of the powder gets converted to hydrogen and little energy is lost through heat."
This process may be efficient, but sodium doesnt grow on trees (or mined out of the ground). The easiest way to get it is.... electrolysis of sodium chloride.
So you've just shifted the electrolysis problem further upstream and instead of using nice friendly water, you're passing current through nasty, mean molten salt.
Not to be overly pedantic but even though this may correspond to the yield, the hydrogen is originally part of the water, not the sodium.
Being able to produce hydrogen in a way that does not use fossil fuels "at all" is a huge step in the right direction.
Another process in development involves bacteria that have a hydrogen waste product, if my memory serves me correctly.
Of course, solar, wind, and geothermal are also reasonable ideas.
The first person/company that is able to produce hydrogen cheaply using renewable resources will be an unbelievably good investment. (Assuming patents are taken care of properly)
Bear in mind that this stuff will take energy to produce and there will be waste to dispose of.
Also bear in mind that electrolysed hydrogen also takes more energy to produce than it will release (until we get perpetual motion sorted out).
So all of this stuff is about finding more efficient ways to generate energy and store it.
In this case the innovation seems to be that this product will make it easy (in water rich environments) to create hydrogen which (it is anticipated) will be easy to make electricity from.
I've made hydrogen by mixing good old caustic soda (sodium hydroxide) with aluminium cans and water.
Year 8 science, same result as this "innovation" although we only got enough hydrogen out of the bottle to inflate a baloon which was able to take off with a 3 metre piece of string drenched in methanol.
lit the bottom as it went by and the whole thing made a very satisfying fireball.
'There is a Light that never goes out.'
Because much of it happens to be in places from which it is rather difficult to obtain it, such as in stars. Even here on earth the hydrogen happens to be bonded with oxygen, therefore we must seperate them first.
Does anyone have a formula for the chemical reaction that takes place when water is added to the sodium / silica powder? How much energy can be extracted from one kilogram of the powder, how much water would it take?
Sheesh, that sounds just like a typical high-school chemistry exam question. But just FYI:
The total reaction is:
2 Na + 2 H2O --> 2 NaOH (in solution) + H2 (gas)
You can split that into the oxidative and reductive half-reactions:
Na --> Na+ (sodium ion) + e- (electron)
2 H+ + 2 e- --> H2
(where the H+ comes from H2O H+ + OH-)
The energy? Well look in any old table of reduction potentials and you find it's -2.71 Volts (relative hydrogen). Multiply that by Faraday's constant (96485 C/mol) and you get 261 kJ/mol. 1 mol of sodium weighs ~23u. (23g/mol)
= 11 MJ / kg is how much you can get out.
It will take the same amount to get the Na metal back from NaOH, of course. Conservation of energy and all that.
It'll take you 1 water per Na. Water weights 18u, sodium 23. So it'll take you 18/23 or roughly 80% of the mass of your sodium (and that's just the sodium, no gel included here) in water.
Would it be feasible to put the powder in a container and replace the container at a "gas station" when all the sodium is oxidized?
Why wouldn't it be?
Would it be feasible to have the sodium de-oxidized at a special processing plant?
Maybe, maybe not. More likely it wouldn't be worth the transport. You can do the regeneration on the spot instead.
In other words, could this be a feasible solution to the storing of hydrogen in a vehicle problem?
Maybe. But that's the reason this is news.
(as a note, as you progress down the alkali metal group, the reaction with water becomes more violent. Lithium and sodium fizz, potassium will ignite on the surface of the water, and you do not want to be around rubidium or cesium [Caesium if your British] if they go into water unless you want to be covered in molten metal.)
As a further note, the reason that there is no hydrogen in the atmosphere is that it is so light it escapes from the atmosphere.
As a final note, silica gel as a support is making leaps and bounds. Binding a reactant to silica gel allow reaction purification by simple filtration, which is always a good thing. I suspect that if their claims pan out, the reason that its less violent is that the Na/SiO2/SiOH is a less powerful reducing agent than pure Na metal [though SiOH's probably react with the sodium forming NaOSi]. But as someone pointed out, pure sodium metal does not exist on the earth. Sodium exists as salts, which have to be electrolyzed to make pure sodium metal (at about 850C to boot).
Old school con, and very dangerous. By alternating the current, you will be generating oxygen and hydrogen at both ends, and it will recombine to release the energy you've put in through electricity immediately.
The story states:
"The most common way in making hydrogen is electrolyzing pure water."
From what I understand, this is wrong. I've heard that most hydrogen is ironically produced as a byproduct of refining oil.
Wikipedia for instance http://en.wikipedia.org/wiki/Hydrogen says that:
"Commercial bulk hydrogen is usually produced by the steam reforming of natural gas."
Well, according to BMW, hydrogen fueled cars are actualy safer than common gas fueled ones.- 2002/22966.html
http://www.bellona.no/en/energy/hydrogen/report_6
Ni.
Sorry, but this is just wrong. Millions of tons of hydrogen are made every year around the world (for ammonia synthesis, for example), and very little of it comes from electrolysis. Thermal reforming of natural gas and other carbonaceous compounds is much more economical.
A tougher problem is upstream. Making sodium is gross and inefficient. It's done from brine (salt domes) the in old chlor-alkali process with mercury electrodes. This needs more [over]voltage 3.5V IIRC than hydrolysis. It is the voltage, and particularly the overvoltage needed to drive the process at industrial scales, that makes the process inefficient.
However, Hydrogen gas has chemical formula H2, and this is neither the same as, nor part of H20 or polycrystalline Na. So the claim to have created hydrogen gas is valid.
You would not get mush of sodium, water and silicon. What you most probably have is a mixture of sodium silicates and sodium hydroxide. pass chlorine through this and then you probably can dump it in the sea without too many problems (NaCl+ silicon =sand (or waterglass) +salt?). Unless you want to sell the sodium hyroxide, it is a quite useful chemical.
.ACMD setaloiv siht gnidaeR
ethanol (AKA alcohol) doesnt take more energy than it produces to make.
...
1- crush sugar cane
2- burn the pulp leftp to produce steam power to drive the crusher
3- ferment sugar cane dip
4- distil the result of fermenatation using whatever is left from the pulp to heat the distiler
5- let the next sugar cane crop capture the carbon spilt in the atmosphere
6-
7- PROFIT!!!
this business model is what drives a considerable part of brasilian cars. my next car will sure be flex fuel, so i can choose between more power (with alcohol) or more autonomy (gasoline).
now, methanol i agree takes more power to produce than what it gives back when you burn it inside an engine
What ? Me, worry ?
Before you make statements like that, you should consider how much water vapor is generated naturally on this planet. If we assume that on average 500cm of rain falls annually all over the earth, then 500l/m^2 of water must have been evaporated, mostly by solar energy. At 2260kJ/kg, that comes out to 5.8e23 joules of solar energy that goes into evaporating water annually. Since the human race currently uses only about 5e20 joules of energy per year, converting to all hydrogen would only create an extra amount of water vapor equal to about 1/1000 of the natural production.
Moreover, unlike CO2, water vapor easily condenses out of the atmosphere, and any problem goes away within a few days. It doesn't just keep building up.
1) The most common source of hydrogen is hydrocarbon reforming, done at oil refineries. It's the only economically viable method for bulk quantities. Thus, hydrogen energy is currently dependent on fossil fuels.
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2) You cannot electrolyze pure water -it's a poor conductor. You need some salt, or other electrolyte. Even then, the amount of electrical energy that goes in is less than the energy value of the hydrogen that comes out. And guess where most of the electricity comes from . .
3) Sodium metal causes a fire when dropped into water because of the hydrogen it releases. The activation energy for the reaction between oxygen and hydrogen is very low, and the heat released from the sodium metal - being converted into sodium hydroxide (aka lye, or Drano)- is more than sufficient to cause the reaction (fire).
4) Sodium metal is made by electrolyzing molten sodium chloride (table salt). A very expensive, energy consuming reaction, not to mention nasty (it releases chlorine gas, also).
5) The amount of energy released when an electron is stripped from a sodium atom is the same, whether it's in water or in silica.The energy is either converted to heat or to some other form of energy. Ever hear of conservation of energy (or mass/energy for nuclear reactions)? Unless they've developed something that can do what the transporters and replicators on Star Trek do, the enrgy is still going somehwere. Entropy demands it, otherwise we'd have perpetual motion machines, and ebergy would not be an issue.
6) Mediating the reactivity of alkalai metals is nothing new - that's what amalgams do.
This story does not deserve the attention it has already received.
MM
Huge SUVs _were_ popular, up until last year. Sales of medium and large SUVs are down 30% from a year ago.
There's a GM Assembly plant near here.
Furthermore, the most common way of producing hydrogen is not electrolysis, but reforming of hydrocarbons (oil and natural gas) Ding ding, we have a winner. That's exactly what I was going to say. At this point, whenever we "make" hydrogen, we release a large amount of CO2 into the air because we're getting the hydrogen from CH4 (natural gas = methane).
main(O){10<putchar((O--,102-((O&4)*16| (31&60>>5*(O&3)))))&&main(2+ O);}
LN2 is cool!
Those sprawling metro areas were made by better public transportation. LA is an example: I remember, after the Northridge quake in 1994, several LA car overpasses collapsed, paralyzing traffic and the city. Critics on Usenet (much higher signal:noise ratio then ;) told Angelenos that they'd be a lot less screwed if they had public transport, which could route around such holes in the network. Angry Angelenos fired back "if you lived here, you'd know how sprawled we are - we could never have streetcars service this farflung city". But then others responded with maps of the LA streetcar network, which ran up into the canyons and out across the flats, when literally no one lived there yet. Which let everyone live in all those places, building the city in its spread-out topology. Until a joint venture of GM, Goodyear and Standard Oil bought up all the tracks, pre-WWII, scrapped the system, and repaved with roads and cars. LA is still a great place for streetcars, topologically and weather-wise. They should put them back. When oil hits $100:gal, people will start talking about it seriously, though it will be too late to do it cheaply - and after LA has burned uncounted billions of gallons of cheap gas.
Amtrak has a similar story, as the robber barons who built the phenomenal US rail system sold out to a government they stuck with a deliberately noncompetitive transport system. So they could safely invest in cars, trucks, airlines and the oil companies that are the blades to those vehicles razors. The US rail system was a blazing success when the country wasn't very dense anywhere but NYC and Chicago. The increased density along the coasts just makes those areas even more ripe for rail.
As for passenger rail's "flexibility" demands, commuter arteries show that's not strictly necessary. In Brooklyn, literally millions of people a day drive across a town on local roads that has highways only around its perimeter. One road, Atlantic Avenue, cuts across town, running from the 3 bridges (& 1 tunnel) to lower Manhattan, to the nexus of 3 or 4 highways that run across the sprawling suburbs. Right past JFK, the major airport, and within a few miles of Jamaica, the existing commuter/subway hub (also connected to the airport with new rail). There is a 4-channel subway line along that road, and a 2-channel commuter rail line alongside it. All underground. The city should run a "car train" continuously shipping platforms from lower Manhattan to the airport parking lots, around that 6-channel rail line, which is mostly unused capacity most of the time. Literally millions of New Yorkers would have a guaranteed 15-minute commute every day, rather than burning gas into the air (and missing home/work) for anywhere from 45 minutes to 2 hours, in each direction, fighting traffic and collisions. There are other "trunk lines" which are mostly just routes for millions of people between two points.
Then there is the long-overdue subway upgrade in the rest of the City. The signaling system dates from the late-1930s, and has become quite the boondoggle in recent years, preventing expansion, threatening years-long outages on major lines after inevitable breakdowns. If they integrated the 3 track systems, and replaced the signals/switches with a "packet switching" system, instead of the current "circuit swithes", we could have an Internet-style subway that trumps the old one like an old "Ernestine" operator-switched one. The flexibility to get a station-to-station trip, anywhere in the system, cutting commute times, congestion and energy consumption by orders of magnitude.
These are expensive capital investments. The AirTrain line from JFK airport to the rail hub, and eventually LaGuardia airport, was at least $8B, probably $15B when it's "done". But that was Giuliani's scam to pay his mafia contractor buddies some of the numbers coming out of the Bubble during his reign, and included behemoth new stations and new rights-of-way thru crowded, expensive NYC land. When we're talking about million
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make install -not war
FTA: "Although it's a small company--it only has three full-time employees"
so I guess only one stinky unshowered nerd
The Answer
The chlorine produced would be no threat to the ozone layer. Chlorine is too reactive to survive in elemental form all the way up to the ozone layer. The entire reason why CFCs were so destructive is because they were so stable they were able to survive all the way to the upper reaches of the atmosphere, where they were finally broken down by UV and released the chlorine they carried. (This process is actually still continuing, even though CFCs have been banned for many years. That's how stable these compounds are.)
Elemental chlorine is not exactly a fun-time gas but it's not going to harm the ozone layer.