"the best prediction was Jules Verne. the Nautilus, a nuclear powered submarine. about 40 years before subs were first built. and 60 years before nuclear power was developed. though he had it fusion powered ( "power of the sun" ) and we haven't controlled fusion yet, only fission." erm no.. the Nautilus wasn't nuclear powered. she ran on electrical power derived as you can see in the following quote from 20,000 leagues := ""Your question will have its answer", Captain Nemo responded, "I will say to you, initially, that there exists on the sea-bed mines of silver, iron, zinc, gold, whose exploitation would be doubtless practicable. But I did not borrow anything from these metals of the earth, and I wanted to take only from the sea itself the means of producing my electricity." "From the sea?" "Yes, Professor, and I did not miss the means. I could, indeed, by establishing a circuit between wires plunged to various depths, obtain electricity by the difference in temperature; but I preferred to employ a more practical system." "Which is?" "You know what sea-water is composed of. In a thousand grams are found 96 1/2 per cent of water, and about 2 2/3 per cent of chloride of sodium; then, in a smaller quantity, chlorides of magnesium and of potassium, bromide of magnesium, sulfate of magnesia, sulfate and carbonate of lime. You see, then, that chloride of sodium forms a large part of it. So it is this sodium that I extract from the sea-water, and of which I compose my ingredients.'' "Sodium?" "Yes, sir. Mixed with mercury, it forms an amalgam that replaces zinc in the Bunsen elements. The mercury never wears outs. Sodium alone is consumed, and the sea itself provides it to me. I will say to you, moreover, that the cells with sodium must be regarded as most energetic, and that their electromotive force is double that of the zinc cells." "I understand well, Captain, the excellence of sodium under theses conditions. The sea contains it. But it still must be manufactured, extracted it in a word. And how do you do this? Your batteries could obviously be used to power this extraction; but, if I am not mistaken, the expenditure of sodium required by the electrical apparatus would exceed the extracted quantity. You would consume more to produce it than you would produce!" "So, Professor, I do not extract it by the batteries, but quite simply employ the heat of the pit coal." "From the earth?" I insisted. "Let us say 'coal of the sea', if you wish", answered Captain Nemo. "And you can work underwater coal mines?" "Mr Aronnax, you will see me do it. I ask you for an only little patience, since you have time to be patient. I point out only this: I owe all to the ocean; it produces electricity, and electricity gives heat, light, motion, and, in a word, life to the Nautilus.""