What are submarines powered by?

Answer 1

Modern submarines are powered by one of 2 primary propulsion methods - nuclear power or diesel-electric.

DE propulsion has been around since John Holland invented the first viable combat submarine with range. The design hasn't changed much in over 100 years, though the technology of course has been greatly improved. The design consists of at least 2 diesel engines that recharge large battery cells, which in turn power an electric motor while submerged. The diesel is also used for surfaced propulsion and while recharging either on the surface, or at periscope depth.

DE submarines today, unlike those of past wars, are primarily used by smaller navies for coastal defense, rather than for long-range strategic purposes. This is because the advent of Nuclear Power for most blue-water navies using submarines leaves the DE submarine at a disadvantage in a tactical situation. Though DE's are extremely quiet on an electric motor, their speed limitations against another boat using NP means they're on the defensive as soon as they make enough noise to be detected. Battery power also limits the scope of electronic and weapons systems they can carry, and their fuel limits their range and capability and speed.

Nuclear Power is the choice of large blue-water navies for submarines, since the USS Nautilus circumnavigated the globe in the '50's without the need for refueling and in record time. Nuclear Power gives naval vessels a huge advantage in the systems it can employ, crew comfort (secondary), and tactical employment. Nuclear submarines can be in a target area gathering intelligence or inserting covert teams long before main Carrier Battle Groups enter the area.