S - 80 - class submarine The S - 80 Class are AIP ( air independent propulsion ) submarine s currently under construction for the Spanish Navy . Four boats have been ordered , three of which are under construction by the Spanish company Navantia at its yard in Cartagena . The submarines are being fitted with a new propulsion system designed for a high degree of autonomy under water . Their mission includes : projection of naval power onto land , naval special warfare , surveillance , protection of naval forces and deterrence . The first was planned to enter service in the Spanish Navy in 2015 , with a second in 2016 , but a weight imbalance issue has been identified which is to delay the project between 12 and 24 months . The construction of the third in the series began in 2009 . The Indian Navy is considering this submarine for its next generation of submarines under Project 75I . Capabilities . The submarines of the S - 80 class are designed to better complete their mission in threat scenarios . Their operational mobility will allow them to operate in remote areas , traveling discreetly at high speeds . Their air independent propulsion ( AIP ) system , of new technological design , will ensure their ability to remain very long periods of time in an area without being detected and their ability to operate in possible conflict zones . Their capabilities include : Propulsion . The AIP ( air independent propulsion ) implemented on the S - 80 is completely different from the French MESMA ( Module Energie Sous - Marin Autonome ) project . The S - 80 ' s AIP system is based on a bioethanol - processor ( provided by Hynergreen from Abengoa ) consisting of a reaction chamber and several intermediate Coprox reactors , that will transform the BioEtOH into high purity hydrogen . The output feeds a series of fuel cell s from UTC Power company ( which also supplied fuel cells for the Space Shuttle ) . The Reformator is fed with bioethanol as fuel , and oxygen ( stored as a liquid in a high pressure cryogenic tank ) , generating hydrogen and carbon dioxide as subproducts . The produced hydrogen and more oxygen is fed to the fuel cell s . The bioethanol - processor also produces a stream of highly concentrated carbon dioxide and other trace gases that are not burned completely during combustion . This gas flow is mixed with sea water in one or more ejector venturi scrubber and then through a new system called SECO ( or CO Removal System ) , developed by Bionet , and whose purpose is to dissolve the " bubbles " of CO in water to undetectable levels . The oxygen and fuel flow rates are directly determined by the demand for power . The AIP power in the S - 80 submarine is at least 300 kW . A permanent - magnet electric motor moves a fixed propeller of a special design , that doesn ' t create cavitation s at high speed . History . In the 1980s France began studies for the replacement of their S - 60 " Daphné " class diesel submarines . The French shipyard DCNI came up with an all - new design called S - 80 , with a teardrop hull and new weapons and sensors , which their government decided not to fund . DCNI then proposed a cheaper option called the S - 90B , an S - 70 " Agosta " class submarine with limited improvements which was again rejected by the French but which was exported to Pakistan . Meanwhile Spain faced the same problem in replacing their " Daphnés " , known as the " Delfín " class in Spanish service , as part of Plan ALTAMAR . Bazán ( later Izar , and then Navantia ) started on a new design but when it started to look like the S - 80 , it was agreed to collaborate in a joint venture based on the French S - 80 . This joint design was shown at Le Bourget Navale in October 1990 . The end of the Cold War meant that funding dried up and the joint venture had to wait until 1997 for their first sale - to Chile - of the new design , which was designated the " Scorpène " class in export markets . The same year Spain started to look again at its requirements , and in 1998 they indicated that they would buy four " Scorpènes " , optionally with an air - independent propulsion ( AIP ) system for greater endurance when submerged . A staff requirement for the S - 80 Scorpène variant was completed in October 2001 . This was soon overtaken by events , as the Armada became more interested in using submarines for power projection than in a more static , defensive role . This shift was codified in guidance of January 2002 from the Chief of Naval Operations and in the strategic defence review of February 2003 . The new requirement called for a larger submarine with better endurance and land - attack missiles , which became known as the S - 80A design . This was an AIP submarine with a hull diameter of compared to for the Scorpène family , a submerged displacement of around 2 , 400 tonnes versus 1 , 740 tonnes , larger rudder surfaces and a different fin position . The Spanish government approved the purchase of four S - 80A submarines in September 2003 and signed a contract with Izar on 24 March 2004 . The original deal was €1 , 756m to design and build four submarines , about US $ 550m per boat , but by 2010 this had increased to €2 , 212m ( US $ 700m / boat ) . The plan envisaged the first boat to be delivered in 2011 but government dithering over who should supply the combat system pushed it back to 2013 . In 2011 Spain ' s budget crisis further delayed the first delivery until 2015 , with the remaining boats being delivered at one year intervals until 2018 . Construction of S - 81 began on 13 December 2007 . In January 2012 the names were announced , honouring three engineers who made submarines and the first commander of Spain ' s submarine force respectively - Isaac Peral ( S - 81 ) , Narciso Monturiol ( S - 82 ) , Cosme García ( S - 83 ) and Mateo García de los Reyes ( S - 84 ) . In May 2013 , Navantia announced that a serious weight imbalance design flaw had been identified which will delay the delivery of the first submarine to the Spanish Navy until possibly 2017 . Excess weight of 75 - 100 tons has been added to the sub during construction and the current design is not able to resurface after diving . A former Spanish official says the problem can be traced to a miscalculation — someone apparently put a decimal point in the wrong place or by the addition of new technologic devices . Lengthening the submarine would create additional buoyancy , though at a cost of €7 . 5m per metre . With the project also suffering with an underperforming AIP system ( which was to allow the submarine to stay underway for 28 days but was only managing 20 days ) the Spanish Defence Ministry announced in June 2013 that Navantia has signed on the US company General Dynamics Electric Boat to help solve the excess weight . References . " This article incorporates material from Spanish Wikipedia "