I saw this being thrown around recently, and I thought I had a general understanding what it is.
I looked it up and its...
British
Thermal
Unit
Wikipedia says:
A BTU is defined as the amount of heat required to raise the temperature of one pound avoirdupois of water by one degree Fahrenheit.
So lets think about this, how does modern science like to measure energy? They like to burn shit up. This BTU measurement is calculated when the matter in question is oxized, and burned.
What do we know about the relationship of water and hydroxy? It stays cool. But that same flame will melt tungsten at 7500 degrees.
If hydrogen, when oxidized and ignited, has a flame that doesn't radiate much light energy nor heat energy compared to a gasoline oxidized flame, how can you compare? I don't think you can. There needs to be a better and more accurate method of measuring energy potential of matter than boiling water.
Here is another way of looking at it. If 4 litres of hydroxy are ignited and pointed directly at a cubic foot of water, It won't do much. Take that same flame, with 4 litres of hydroxy, and point it to a tungsten element, and then put that redhot thing in the water, and whoosh. See what I mean?