Final answer:
Naval vessels use nuclear power and diesel engines as power sources in place of their main engines. Nuclear power is used for its endurance and power density, while diesel engines are chosen for their reliability and ease of refueling.
Step-by-step explanation:
Naval vessels often utilize alternative power sources to their main engines for propulsion and onboard power requirements. Two significant sources are nuclear power and diesel engines. Nuclear power, used in some naval ships, especially in submarines and aircraft carriers, employs a nuclear reactor to generate heat. This heat is used to create steam that drives turbines connected to propellers, enabling the ship to move. Nuclear propulsion offers the advantage of long endurance and high power density, enabling these ships to operate for long periods without the need for refueling.
On the other hand, diesel engines are conventionally used in many naval vessels for their reliability and easier refueling compared to nuclear power. Diesel engines work by combusting diesel fuel to produce mechanical energy that drives the ship's propellers. These engines are often employed on smaller ships, such as frigates, destroyers, and support vessels, where the use of nuclear power is not practical or cost-effective.