Re: Hydrogen from water?

There seem to be 2 parts to your question:

1) Is hydrogen gas is involved in humidity, and can be obtained by dehumidifying air.

2) How hydrogen might be obtained from water, as an alternative fuel source.

First off, a water molecule is made of 2 hydrogen atoms and 1 oxygen atom. These atoms are strongly attached, or bonded, in the water molecule. The water molecules that are close together in liquid water move further apart when the water is boiled or evaporates, changing from liquid to water gas, or steam. The water gas is still made of 2 hydrogen atoms and 1 oxygen atom bonded together into water molecules - the hydrogen is not separated out.

When water as a gas ("steam") is present in air, we refer to this as humidity. When we dehumidify air, we remove the water gas from the air by changing the water back into its liquid form - still consisting of water molecules in which the hydrogen and oxygen atoms are bonded together, so hydrogen does not separate out.

So, since water is made of 2 hydrogen atoms and 1 oxygen atom, how can we obtain hydrogen from water? To break the bonds holding the water molecules together, and release the hydrogen, we must supply a lot of energy. For example, we can produce hydrogen from water using electrical, heat, or light energy:

1) Electrical Energy - hydrogen can be obtained by supplying electrical energy to water; this is called the electrolysis of water. This is a frequent experiment in schools and at home; a battery (used to supply electrical energy) is connected to two electrodes, which are submerged in water. Hydrogen bubbles from one of the electrodes, oxygen bubbles from the other.

2) Heat Energy - If water is passed over coal (carbon) at very high temperatures, the heat supplies enough energy to break apart the water molecules so that the oxygen combines with the carbon, forming carbon dioxide. Hydrogen gas is left over. This is a major way that we currently obtain large amounts of hydrogen.

3) Light Energy - Hydrogen can be produced from water using approaches such as variations on photosynthesis.

More insight into the subject of hydrogen, hydrogen production, and hydrogen as a fuel source can be obtained at:

Hydrogen - FAQ (frequently asked questions)

Hydrogen Infonet