Concept design and feasibility study of an entirely battery powered naval submarine

Abstract

This thesis describes a feasibility study of an entirely battery powered submarine. An entirely battery powered submarine will be air independent, which will provide the submarine tactical advantages. The feasibility is investigated by the creation of a concept design and by performing an operational capability study.

Implementing an entirely battery powered submarine system into a submarine will have a large effect on the design of a submarine. The diesel-generators and all support systems will be removed. This will reduce the number of systems on board the submarine significantly. The space provided by the reduction of these systems can be used to increase the number of installed batteries. Furthermore, this will result in a reduction in the auxiliary load of approximately seven percent. The reduction in systems will also have multiple second order effects. The safety characteristics will improve; there will be less pressure hull penetrations and the risks of fire decrease. Furthermore, the crew size can be reduced with approximately 20\%.
The usage of lithium-ion batteries will influence the battery system design and the safety characteristics of the battery pack. There are also several other systems which will be influenced by the implementation of the new power plant; the high pressure air system, the HVAC system and the electrical system. The design of an entirely battery powered naval submarine will be volume critical. Approximately the same amount of lead-ballast as a diesel-electric submarine will be required to reach a natural buoyant state. Stability is not a problem when all battery compartments are created low in the submarine design.

Independent local to medium range missions are feasible for an entirely battery powered submarine. For example, the created concept design has a displacement of 1905 tons and will be able to reach a range of 1940 nautical miles and has an endurance of 24 hours. This makes an entirely battery powered submarine an interesting option for navies who use their submarine for homeland defence missions. Independent missions with a long range and endurance are not feasible. The range and endurance of an entirely battery powered submarine is expected to be four to six times lower than the range of a diesel-electric submarine. Missions which require a longer range or endurance can be feasible when on sea charging is performed.

An entirely battery powered submarine has the advantage of an air independent propulsion, therefore the total range and endurance can be sailed without needing to surface. Compared with a diesel-electric submarine with an AIP system, the submerged endurance of an entirely battery powered submarine is 1.5 times higher. However, the total range and endurance of an entirely battery powered submarine will be three times as low. The long submerged endurance of an entirely battery powered design makes air quality control of great importance. Much attention must be paid to carbon dioxide absorption, oxygen production and other systems and materials which can influence the air quality.