I have always wondered how Turkish submarines of the MILDEN Series can be built and which energy sources must be used in order to be competitive.
Nuclear energy is out of the question, at least for the time being, because strict restrictions prevent us from getting anything viable in the next 10-15 years.
An AIP system would probably be the best solution, but I personally don't think it's optimal or competitive enough compared to nuclear submarines.
Because you have to refuel after 3-4 weeks.
I find the concept of radionuclide batteries in a cluster (30-40 smaller RTGs) + with multiple high power sodium (natrium) ion batteries + Supercapacitors charged by thermoelectrics much more interesting.
It has a similar characteristic to nuclear submarines in that RTGs can easily provide continuous power to the high power battery system for decades. Although the energy output would be low, the continuous charging would equalize this as you could switch between the battery blocks while charging.
The high-performance batteries would then only have to be replaced every few years due to their natural wear and tear.
The system is absolutely silent in operation.
The submarine can remain under water for months, after which only CO2 filters, food etc. are the decisive factor, as with a nuclear submarine.
Especially for first strike/counter-strike, espionage and inflation missions in foreign waters it would make more sense.
There are hardly any restrictions on RTGs with a strontium 90 and amercium 241 base, of course you would have to increase the energy density a little further and shield the submarine well because of the radiation from the RTGs, as with a nuclear submarine, but it would certainly be feasible.
The submarine would be larger and heavier overall, but for Turkey it would be the best solution I know of to achieve a similar performance profile to a nuclear submarine and make itself vulnerable to international attack.
