What I have heard more than once is that diesel-electric subs are quieter than nuclear submarines. The fact that they can operate on battery power and that the mechanical pumps are less noisy than a nuclear submarine's steam turbine are typically pointed out as the reasons. No amount of quieting can get past that. Also any quieting techniques you use on a nuclear submarine can also be used on a diesel-electric (anechoic tiles, propeller designs, etc). This is why US carrier groups have often been surprised by diesel-electric submarines of other nations in exercises. The USA Navy mostly trains against their own nuclear submarines. They had to purchase a Swedish AIP submarine in order to train against modern diesel-electric and even that design is now out of date. In a conflict which is close to the Chinese coast, like in Taiwan, I think China would have a definitive advantage. Further away the lack of capability of Chinese nuclear submarines is an issue though. I do expect that as AIP submarine and lithium-ion battery technology gets used on Chinese submarines, and if it they enlarge them in a similar fashion to Japanese submarines then the diesel-electrics could pose a significant threat even in the high seas. They could easily strike places like Guam or Okinawa. In WWII the technology for diesel-electrics was much less advanced and the submarines operated across the entire Pacific Theater given appropriate basing and support ships.
Where the nuclear submarines shine is in high-speed, high-depth operations, on long range missions. Or for building large boats which have more capability to carry large payloads like SLBMs.
Where the nuclear submarines shine is in high-speed, high-depth operations, on long range missions. Or for building large boats which have more capability to carry large payloads like SLBMs.
