I've heard that hydrogen is a good energy carrier but unsure why this is if they have no chemical bonds.
What defines if something is a good energy carrier?
You need to differentiate between Hydrogen atoms and Hydrogen molecules.
Hydrogen molecule consists of 2 atoms of hydrogen: H2.
So the energy is indeed stored in the bond between two H atoms.
H2 has the highest gravimetric energy density of all known substances: 120 kJ/g (as a comparison, gasoline is 44 kJ/g).
I would define a good energy carrier based on its gravimetric and volumetric energy density. Hydrogen is the best for gravimetric, but it is a gas. Compactly storing hydrogen is challenging compared to gasoline which is liquid.
Check this reference with some nice figures that compare different energy carriers: Article Hydrogen: The future energy carrier
Dear Edwin Harvey,
The most common fact is that "The energy is stored in the chemical bonds. When you break the bonds, you get energy."
In your context, the hydrogen molecule I guess, perhaps it can be dissociated either homolytically or heterolytically and bonds with other elements and forms hydrides. These Metal hydrides store hydrogen by chemically bonding the hydrogen to metal or metalloid elements and alloys. Some hydrides can adsorb hydrogen at or below atmospheric pressure, then release the hydrogen at significantly higher pressure when heated.
This is the extremely naive question. "I have heard" sounds funny.
Dinesh Kumar Madheswaran " When you break the bonds, you get energy" is not correct. You don't release energy, but consume it. The energy is released in chemical reactions when the reaction Gibb's energies are negative.
Loris Lombardo I would agree with you, if you mention that hydrogen is a good energy carrier when it's intended to react with O2.
The energy comes from 2H2 + O2 -> 2 H2O reaction. Oxygen is in the air, and you need to deliver H2 to get energy.
Hydrogen can be stored indirectly in chemical compounds, such as methanol or DME, but directly in pressure cylinders and tanks. Storage in some highly porous bodies is conceivable, but this would not be cost effective.