the energy that can be obtained by burning it with fuel, making this process completely unsuitable for a power engine.
How, then, did non nuclear submarines operate at all? The modern submarine, in its basic form, was invented before 1900, and submarines played a major role in both World Wars. The first nuclear submarine, the USS Nautilus, was not launched until 1954 (Humble, 1981, p. 124). Somehow, non nuclear submarines were made to work. Three basic approaches were used. One was to carry oxygen on board, or another oxidizer such as hydrogen peroxide that could also be used to burn fuel. This, however, was so bulky as to be impractical.
The second approach was to use a conventional diesel engine on the surface, and use it to charge electric batteries that could be used underwater. This was and is the standard method used for non nuclear submarines. Batteries, however, are bulky, and store very limited power. Diesel electric submarines thus can only creep along at low speed underwater, and cannot remain submerged at all
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