One of the great disadvantages of nuclear submarines
is the vast cost of the power plant
and the required supporting infrastructure
. These costs have limited the number of nations operating nuclear submarines.
The holy grail of submarine designers since WWII has been a power plant that does not require air, yet provides endurance and performance
approaching that of a nuclear submarine. To date, this level of performance has not been met. Several systems provide short bursts of greater speed and submarged endurance, but not long term increases. Current systems take up a great deal of the limited weight and volume available to the submarine designer. In addition, they require the use of toxic chemicals or dangerous substances such as liquid oxygen
or hydrogen peroxide