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I know someone knows Chemistry
Posted: Sun Jun 29, 2008 9:40 pm
by brunota2003
I know someone here knows something about Chemistry...
I am curious as to how much energy High Temperature Water Splitting would give off? I know the temperatures needed are between 1000 to 2000*F, if I read correctly...but how much energy does it give off as the atoms are separated, if any?
What about at 2500*F?
Re: I know someone knows Chemistry
Posted: Mon Jun 30, 2008 5:59 am
by Skyhawk
If by water spitting you mean separating water into hydrogen and oxygen then the answer is that it does not give off energy but rather requires energy.
Re: I know someone knows Chemistry
Posted: Mon Jun 30, 2008 6:07 am
by Cryomaniac
Skyhawk wrote:If by water spitting you mean separating water into hydrogen and oxygen then the answer is that it does not give off energy but rather requires energy.
I was going to post that, but I wasn't sure that's what he meant.
Posted: Mon Jun 30, 2008 7:45 am
by brunota2003
Ok, thank you! and yes, that is what i meant
Re: I know someone knows Chemistry
Posted: Mon Jun 30, 2008 7:53 am
by Ed Mahmoud
That is why hydrogen, for use in fuel cells, is more a storage medium, like a battery, than a fuel.
Hydrogen does not exist in useable quanitities in its diatomic molecular state.
At 100% efficiency, it takes as much energy to separate the hydrogen and oxygen as is released when they react again, and since nothing is 100% efficient...
Fuel cells as an automotive "fuel" requires electrical generating capacity. Build nuke plants, or plaster the desert in solar cells, or build more wind towers, and one can theoretically reduce carbon dioxide emissions.
Re: I know someone knows Chemistry
Posted: Mon Jun 30, 2008 8:37 am
by gtalum
Ed Mahmoud wrote:Fuel cells as an automotive "fuel" requires electrical generating capacity. Build nuke plants, or plaster the desert in solar cells, or build more wind towers...
Better yet, do them all at once, plus newer technologies like tidal power, geothermal, and ocean thermal energy. Nuclear is a decent stopgap for now and the next few decades, but unless we make big strides in fusion quickly it's as resource-limited as oil since there just isn't a lot of easily-accessible uranium on Earth.
Re: I know someone knows Chemistry
Posted: Mon Jun 30, 2008 5:18 pm
by MGC
Correct me if I am wrong but isn't H2 made by breaking down natural gas? I was reading on the net the other day about the new nuclear power plants that are currently being designed that will allow H2 to be produced. Instead of using pressurized water they will use gas to cool the reactor core, thus allowing for higher temperatures needed to crack water into H2 and O2.....MGC
Re:
Posted: Mon Jun 30, 2008 7:59 pm
by DanKellFla
brunota2003 wrote:Ok, thank you! and yes, that is what i meant
What units do you need? Joules... Ergs..... How much water are you talking about? Are you talking about Electrolisys? That can be done with a very small amount of energy, but, it will take a long time to break down a given volume of water. You can use a household battery even. But, be careful, making pure Hydrogen is dangerous.
Re: I know someone knows Chemistry
Posted: Mon Jun 30, 2008 9:24 pm
by Ed Mahmoud
MGC wrote:Correct me if I am wrong but isn't H2 made by breaking down natural gas? I was reading on the net the other day about the new nuclear power plants that are currently being designed that will allow H2 to be produced. Instead of using pressurized water they will use gas to cool the reactor core, thus allowing for higher temperatures needed to crack water into H2 and O2.....MGC
Hydrogen can be made from methane (main component in natural gas) as well from what I understand, but as a transportation fuel alternative to fossil fuels, well, methane is a fossil fuel.
Natural gas, with only a single carbon atom, however, is the cleanest of the hydrocarbons, if one accepts AGW as fact. I do know back in the early 90s (probably still do) certain Texas state agencies operated cars modified to run on CNG or gasoline.
Posted: Tue Jul 01, 2008 8:16 am
by gtalum
My favorite new energy technology is
Carbon Dioxide Recycling. In a nutshell, we can use carbon dioxide from the atmosphere and "crack" the CO2 into hydrocarbons like gasoline and others that we need. The net effect is a carbon neutral energy source (assuming the electricity used to crack the CO2 is generated by renewable or nuclear energy) and also a virtually limitless energy source.
Re:
Posted: Tue Jul 01, 2008 10:02 am
by Cryomaniac
gtalum wrote:My favorite new energy technology is
Carbon Dioxide Recycling. In a nutshell, we can use carbon dioxide from the atmosphere and "crack" the CO2 into hydrocarbons like gasoline and others that we need. The net effect is a carbon neutral energy source (assuming the electricity used to crack the CO2 is generated by renewable or nuclear energy) and also a virtually limitless energy source.
Isn't that sort of reverse "cracking" though? Since cracking makes long Hydrocarbons shorter.
Re: Re:
Posted: Tue Jul 01, 2008 11:06 am
by gtalum
Cryomaniac wrote:Isn't that sort of reverse "cracking" though? Since cracking makes long Hydrocarbons shorter.
Intuitively it's "reverse" cracking, but in the industry they call it "cracking" even when they are making longer chains. They already do this with petroleum during times when demand for heating fuel and diesel are higher than normal and demand for gasoline and other shorter-chain blends is lower.
Re: Re:
Posted: Tue Jul 01, 2008 11:32 am
by brunota2003
DanKellFla wrote:brunota2003 wrote:Ok, thank you! and yes, that is what i meant
What units do you need? Joules... Ergs..... How much water are you talking about? Are you talking about Electrolisys? That can be done with a very small amount of energy, but, it will take a long time to break down a given volume of water. You can use a household battery even. But, be careful, making pure Hydrogen is dangerous.
I was just curious as to what all was needed...I know for the lower temperatures it requires energy (i.e. electricity), but did not know if the same held true as the temperatures increase.