The P'tra class power generator is a Klingon structure that is part of colonies of the Klingon Empire.
While appearing only rudimentary in design, they are reliable power structures that supply the life blood to the colony. Due to this importance, they are well protected but do not have an enrivonmentally sound shielding system for the generators which allows background radiation to filter as the Klingons choose to disregard systems for personal safety. Despite this, they do provide the essentials for the colony as well as the necessary backup facilities should it be required. (TOS video game: New Worlds)