India's 25 year old Project 75I is in limbo over AIP Intellectual Property (IP) tender rules.
In mid February 2022 it was reported Russia advised India Russia is withdrawing its Amur-1650 "paper" design from 75I contention. Instead Russia is offering the non-AIP, 25 year old, Improved Kilo "636" class.
Project 75I, for six future SSKs, is all about ambitious Indian demands for detailed, operational,Air Independent Propulsion (AIP) designs from contenders before India selects a winning contender. India also has liability demands which contenders consider onerous.
Another blockage is India offering insufficient money for an AIP submarine. India has quoted a "43,000 crore" equivalent to less than US$6 Billion, projects cost for six 75I submarines for years. That money is deemed insufficient, given India's intentions for the AIP technology.
Sweden (with its operational Stirling AIP) removed itself from the 75I contest around 2019. Although it is possible Sweden sold its Stirling AIP technology to China - for China's Yuan-class (suspected Stirling) AIP submarine project. Alternatively Chinese intelligence may have gathered some Stirling technology (from legal users Sweden, Japan and Singapore) and then China semi-parallel developed working Stirling.
The remaining 75I finalists/contenders who might meet India's 75I requirement for (at sea tested) operational AIP are Germany and South Korea. Both countries don't want to hand over their Fuel Cell AIP secrets before India pays a large amount of money for this AIP. Given this AIP technology was developed in Germany - Germany may hold enough IP rights to block South Korea selling this AIP to India.
This is within an environment that India is still struggling to develop its ownoperational AIP technology. With Fuel Cell technology in hand India may fulfil its long held intentions to retrofit working AIP to its six Kalvari-class French designed Scorpenes. France, also without at sea, operational, 2nd or 3rd generation AIP, would also gain from running this retrofitting process.
Another concern is that India always intended Russia (India's most important arms supplier) would win 75I. Russia has been attempting since the late 1940s to produce an efficient AIP system. Russia might even pay India for German/South Korean sourced Fuel Cell AIP technology. Russia would then place such AIP in its, thus far unsuccessful, Lada-class submarines and export such technology in its future Amur-class subs.
So Project 75I continues to struggle, stalled by its AIP, at low cost, ambitions.