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Other than electrolysis - can H2O be cracked into hydrogen and oxygen at what temperature and how are they kept separated?
I recently took a corrosion and fuel cell course where we discussed this topic. It is actually a very relevant question and, if this could be done on the cheap, it would be a reliable way of producing hydrogen as a fuel. Using solar concentrators, it is possible to heat water to approximately 1500 to 2500 K. At these temperatures the thermolysis of water is possible and is about 2 % efficient. According to Etievant et al.1 the costs and longevity of the equipment needed for this solar conversion makes its efficacy not "promising."
The problem once creating the hydrogen is how to store it. Some places just use the steam (to drive pistons) or the hydrogen (for combustion to drive pistons) for engines on location to create electricity. This is great! But, if one wants to create hydrogen for sale as an automotive fuel, the hydrogen will have to be efficiently stored for transportation to fuel stations.
Although the hydrogen would be produced at an elevated pressure, it would still need to be compressed for storage. Also, first one would need to remove large amounts of oxygen to produce a useable purity of hydrogen gas. One of the first methods used for the separation of hydrogen from the mixture was porous ceramic membranes composed of zirconia2. These types of membranes allow hydrogen to permeate, while not allowing oxygen to pass. Other methods are available for separating the two gasses. The current technologies for compressing gasses into stainless steel tanks requires a large energy input and creates a relatively low density fuel.
The solution to the storage of hydrogen is to store hydrogen gas in a solid. Some solids, such as the metal palladium, can store more hydrogen per unit volume than current methods of compressing gasses. Other efforts have focused on using nanotube based solids to store hydrogen as opposed to palladium. The issue with this is the difficulty in producing a commercially available solid that can absorb the gas reliably and quickly, then dispense it on demand--as combustion engines and fuel cells will have different fuel/energy requirements depending on driving conditions. As you can see, these ideas are great, but lots of this work is experimental--There are some promising results.
Others have suggested using the sun to power photovoltaic cells used to electrolyze (use electricity to split) water to hydrogen and oxygen. This is a good idea as well! Usually the electricity would come from carbon based sources, not the sun. After water is electrolyzed free of charge by the photovoltaic cells powered by the sun, then the processing of the gasses and same storage problems apply. It's just a carbon free way to electrolyze water. [1] Etievant, C. Solar Energy Muter. 1991, 24, 413. [2] Abraham Kogan, International Journal of Hydrogen Energy, 2000, 25, 1043.
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Water has a very stable molecule, and I don't think there is any dissociation due to temperature. Water is routinely taken into its supercritical region in power plants without dissociation. As you suggest it would be difficult to separate the hydrogen and oxygen in any case.
What else can I help you with?
When cap rock is cracked it is called?
aquifier
Why high tmax means more maturity of kerogen?
tMax is the temperature at which maximum hydrocarbons are emitted during the S2 phase of pyrolysis. During the S2 phase, only kerogen is emitted as all other hydrocarbons should have been released during the S1 phase. A higher tMax indicates that the kerogen required higher pyrolysis temperatures to crack. A lower tMax indicates that the kerogen requires lower pyrolysis temperatures to crack. Kerogen cracked at lower temperatures (lower tMax) is more immature since it did not encounter equal temperatures/pressures in situ. Kerogen cracked at higher temperatures is said to be more mature, since all easily accessible kerogen was already cracked in situ (indicating a prolonged exposure to heat and pressure).
Why does flowing bath water sometimes give you an electric shock?
It could be that a heating element in your water heater, if is electric, is cracked. This would allow electricity to flow through the water and be felt in the stream of water.
What type of pollutants can diesel emit?
Diesel exhaust may contain:D.P.M. That's is diesel particulate matter. Microscopic particles that stick inside your lungs.Unburned dieselSulfate particulatesAldehydes and ketonesLighter hydrocarbons from cracked dieselCarbon dioxideNitrogen oxides
Are Mercury glasses safe?
no because if dropped the mercury can spill causing poisoning, and the fumes are also poisonous
How long are cracked eggs good for before they spoil?
Cracked eggs are good for about two hours at room temperature before they spoil. It is best to refrigerate cracked eggs and use them within two days to ensure freshness and safety.
How long do cracked eggs last before they spoil?
Cracked eggs should be used within 2 hours if left at room temperature, or within 2-4 days if refrigerated.
What can cause the temperature light to come on?
Low Colant level, Bad thermostat, Bad sensor, cracked head
What type of adhesive is best for repairing a cracked fire pit?
For repairing a cracked fire pit, it is best to use a high-temperature adhesive specifically designed for outdoor use. This type of adhesive can withstand the heat from the fire and provide a strong bond to hold the cracked pieces together.
What causes temperature in Chevy S-10 to rise?
Several possibilities in order of expense: thermostat, coolant leak, water pump, plugged radiator, bad head gasket, cracked head, cracked block.
Where is water formed?
Hydrogen and oxygen readily combine, releasing energy. If you have ever heard of hydrogen powered cars--this is how they expect to run. The oxygen is freely available in the atmosphere via photosynthesis. The hydrogen, however, must be cracked from water (a net loss) or from hydrocarbons--the chief source of which is fossil fuel.
What is the comparative of cracked?
The comparative form of "cracked" is "more cracked."
Why did the window crack for no reason?
The window cracked for no reason due to a sudden change in temperature or stress on the glass, causing it to break spontaneously.
What part of speech is cracked?
Cracked is a verb and an adjective. Verb: The egg cracked when she dropped the carton. Adjective: He suffered a cracked skull.
What are the common causes of cracked porcelain and how can it be prevented or repaired?
Common causes of cracked porcelain include impact damage, thermal shock, and improper installation. To prevent cracks, handle porcelain items carefully, avoid sudden temperature changes, and ensure proper installation. Cracked porcelain can sometimes be repaired using epoxy or professional restoration services.
How do you fix a slanted tire?
A slanted tire is a serious safety hazard. It can mean the tread is separated or the wheel housing is cracked. Either can cause a potential accident. It is best to either change the tire, or get it checked.
How is Ethane and propane are cracked into ethylene and propylene?
Ethane and propane are cracked into ethylene and propylene through a process called steam cracking. In this process, the hydrocarbons are heated to high temperatures in the presence of steam, causing them to break down into smaller molecules like ethylene and propylene. These smaller molecules are then separated and collected for further processing.
