You are not logged in.
Pages: 1
The demonstrated possibility of producing blended hydrogen and oxygen gas from seawater by exposing it to photons of electromagnetic radiation at radio frequencies can be observed in several convincing video clips by searching eg. Google under "salltwater combustion". There's a lot of discussion regarding the topic, but nothing about the possibility of "burning" water (to which NaCl has been added) in vacuum. With a flame temperature of 3,000 F, surely some practical use can be made of this reaction in space?
Offline
As a way to convert sunlight into a high thrust rocket, yes.
Use what is abundant and build to last
Offline
Of course, the questions regarding the boiling state of water in vacuum and the manipulation under microgravity conditions remain to be addressed--just one example of what the ISS is for.
But, on Mars--once local water sources have been located and mined--the (presumably already-salty) ice could be transported and stored outside the habitats, melted by concentrated sunlight as needed,and "burned" like cordwood outside or inside, for creature comforts ranging from life support to cooking by gas ... and for on-site smelting of ores, scraped from the surface or dug inside caverns and tunnels, and the casting and alloying of resultant metals.
Offline
Uh no
It takes more energy to break the water down into H2 and O2 than you get from H2/O2 burning. You can't "burn" only water. I can give you math to prove my point if you want.
These "RF photons" are just high-powered microwaves, which by the way, the sun does not produce. You are better off using the electricity directly than breaking down water only to immediately recombine it.
And before you ask, no, you can't bottle a mixture of Hydrogen and Oxygen without too high a risk of it blowing up.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
Offline
My object in refering to the process as "burning" was only to introduce the subject to the Mars Society and await members' reactions.
Elsewhere on the Internet regarding this topic, most of the commentary consists primarily of objections involving energy conversion efficiencies, including the math straight out of the Physics textbooks. But no discussions regarding uniqueness of the process which, unlike electrolysis, produces hydrogen and oxygen together on demand--which could actually be combusted on Mars in the atmosphere outside of the habitats, and used for smelting, etc.
No question, the addition of photoelectricity derived from the Sun or from nuclear powerplants would be needed to power the rf generators
The means of storing the water, I've already suggested, could be the form of mined dirty-ice.
I don't know of any industrial H2/O2 mixtures being piped or bottled under pressure. I'd hoped that some original ideas, besides the obvious conversion efficiency objections, might result from introducing this topic, already extensively discussed currently elsewhere on the Internet, for applications on Mars, or the Moon for that matter.
Offline
Why are we worried? Per capita energy will be abundant on Mars. There will be more than enough to spare for splitting water if that is what is required.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
Offline
Why are we worried? Per capita energy will be abundant on Mars. There will be more than enough to spare for splitting water if that is what is required.
No it won't.
The Solar Flux near Mars is considerably lower than Earth. To get enough energy to electrolysis useful amounts of fuel will require very large array of solar panels and a pretty hefty battery to store the energy at night.
It can be done, but it will be no easy task and will require a large investment.
Offline
Why are you so Optimistic about energy levels on Mars? If we had tech like that we wouldn't be worrying about energy.
Unless you mean nuclear, which would be a very tricky politcal obstacle.
If energy is going to be so abundant, lots more places suddenly become more attractive than Mars.
Use what is abundant and build to last
Offline
Why are you so Optimistic about energy levels on Mars? If we had tech like that we wouldn't be worrying about energy.
Unless you mean nuclear, which would be a very tricky politcal obstacle.
If energy is going to be so abundant, lots more places suddenly become more attractive than Mars.
Exactly! the question must always be asked "why don't we currently do this on Earth?"
Offline
There is no such thing as a perpetual motion machine. You can't get more energy out than you put in. The physics law of conservation of energy prohibits it. Furthermore, any conversion introduces randomness which is a source of energy loss. Energy to entropy. All this means it takes more energy to split water into hydrogen and oxygen than you get form burning hydrogen/oxygen.
If you want to use microwaves to heat water for propulsion, there already is a device which does this, it's called MET: Microwave Electro-Thermal thruster. It boils water to steam for thrust. It's Isp is higher than chemical combustion, but lower than other forms of electric propulsion. It's energy is requirement is more than chemical thrusters (which use none) but lower than high Isp forms of electric propulsion. It's a medium/medium compromise.
However, it uses liquid water as propellant since water flows readily through feed lines and valves. For one thing, liquid water absorbs microwaves but ice does not, which is why it takes so long to thaw frozen food. The skiff of liquid water on the outside heats, which melts more of the food to release more liquid water, which absorbs more heat, which melts more frozen food, etc. Once a significant portion of the food is thawed, the rest thaws quickly but it's slow to get started and you have to be careful not to cook the outer layer of food while the core is still thawing. So you can't use ice as propellant.
One guy working on this as a home project, and very enthusiastic about MET, gave a presentation at a couple Mars Society conferences. It's old news to the Mars Society.
You can find more about MET at IEEE.
As for storing hydrogen and oxygen for fuel, that's normal rocket fuel. Cryogenic liquid hydrogen and liquid oxygen are normally used, they can safely be stored as long as they're separate, 2nd and 3rd stages of the Saturn V, the upper stage of Saturn 1, and external tank of the Space Shuttle use LH2/LOX.
Getting back to electrolysis, there are various ways to split water into hydrogen and oxygen. Adding salt does reduce the energy required, but the laws of physics set a minimum energy and scientists have already studied the mixture to death. Using microwaves or other means results in mixing hydrogen with oxygen, which is highly flammable. Microwaves consume more electricity to generate than just normal electrolysis. Normal electrolysis bubbles hydrogen from one electrode, oxygen from the other. In gravity, simply put a funnel in the water over each electrode and you get a single pure gas in each hose. Simple and safe.
Offline
But no discussions regarding uniqueness of the process which, unlike electrolysis, produces hydrogen and oxygen together on demand--which could actually be combusted on Mars in the atmosphere outside of the habitats, and used for smelting
Well yeah it is unique, but that doesn't change the fact that its a stupid waste of energy. Who cares if it produces H2/O2 "on demand?" You would get more heat feeding a bunch of resistance or inductance coils then a bank of high-powered microwaves to split water to turn right back around and burn it.
And remember, the mixture is far too flammable to do anything with, including separate. Besides, you aren't going to go wasting precious Martian water even if it were more efficient, instead sticking with direct heating.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
Offline
Well, shoot--I thought I'd uncovered something useful, but now I don't see it anymore. To sum up: A specially developed portable solid-state microwave power generator/transmitters should be possible, but powering it without a nuclear generator remains a problem on Mars. I have no doubt that excavatable subsurface water-ice contaminated with all sorts of salts will be discovered and that landings will be zeroed-in on the most likely locations, rendering water not all that scarce. But melting the ice will remain a problem. Once melted, low voltage dc from solar batteries should suffice for electroytically splitting the H2O once melted, and storing the resulting hydrogen and oxygen safely bottled separately. Oxy-hydrogen torches would still be possible in the CO2 atmosphere outside.
I wonder what the current "Saltwater Combustion" experiments taking place in Florida will come up with? Not another "Cold Fusion" fiasco, since the effect can be demonstrated on demand. A solution looking for a problem perhaps?. Shall I leave it in the Forum for a while, to find out, or kill it now?
Offline
I think the only practicable application for this would be an H2/O2 torch, and then a portable torch would be infinitely less heavy if you just used bottled gases made from electrolysis.
Considering how they said "RF energy" like it was something magical, I have a bad feeling its a cold fusion wannabe... "power your car with water!" blah blah blah.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
Offline
I know, I know--it goes way back, I remember, to the 1930s when the highways began to replace the rails. Hydrogen to fuel private automobiles is another. Personally, I hope to live to see plug-in hybrids--which don't seem as pie-in-the-sky--so I can afford to live further out in the country....
Offline
Silicon nanowire electrode Lithium ion battery powered plugin hybrids, with serial motor arrangement (motor as generator only).
Powered by Generation III+/IV nuclear reactors burning recycled-from-spent-rods MOX fuel and/or Thorium in addition to U-235.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
Offline
The demonstrated possibility of producing blended hydrogen and oxygen gas from seawater by exposing it to photons of electromagnetic radiation at radio frequencies can be observed in several convincing video clips by searching eg. Google under "salltwater combustion". There's a lot of discussion regarding the topic, but nothing about the possibility of "burning" water (to which NaCl has been added) in vacuum. With a flame temperature of 3,000 F, surely some practical use can be made of this reaction in space?
Thermo-chemical production of hydrogen is likely to be more economic, as it does not need to start with a refined electricity source and for temperatures of 900C it can be up to 50% efficient. The heat can come from a solar heliostat or high temperature nuclear reactor.
The hot hydrogen gas produced can then be reacted with nitrogen to produce ammonia, or better still, carbon dioxide released from calcium or magnesium carbonate to produce methane, methanol, dimethyl-ether or best of all, dimethyl-ether carbonate, a dense fuel which requires no refrigeration and has properties similar to heating oil - a good rocket propellant.
Offline
Pages: 1