Zero Point Module

A Zero Point Module, abbreviated ZPM, is a power source of great magnitude.

Overview
The device capable of generating immense amounts of energy utilizing zero point energy which derives from a phenomenon known as the quantum foam (subatomic wormholes opening and closing constantly in and out of subspace). The ZPM was created by the Ancients millions of years ago. The amount of energy generated by three ZPMs is sufficient to power an energy shield over a city the size of Manhattan for 10,000 years, as well as for interstellar travel.

City-ships such as Atlantis utilize ZPM technology and requires three ZPMs to be fully functional, though Atlantis only requires one to activate most systems.

Like many types of Ancient technology, the ZPM appears crystal-based.

Encountered ZPMs
Colonel Jack O'Neill also built a crude ZPM out of comon materials when he had the Ancient Database downloaded into his brain, in order to reach the only race that could help him: the Asgard.

SG-1 procured a ZPM on Proclarush, which was used to power the Ancient Outpost in Antartica. It was used to power drone weapons to destory the Goa'uld fleet under the control of Anubis. It was later used to power the gate for the Atlantis Expedition, in order to reach the Pegasus Galaxy and Atlantis.

Camulus found an Ancient outpost with a fifty percent charged ZPM. However, Camulus could never make it work (possibly becuase he lacked the ATA gene) so he tampered with the ZPM, rigging it to explode if linked to an electrical charge. Bill Lee estimated that if detonated, the tampered ZPM had the energy potential to destroy Earth, while Samantha Carter estimated that it could have destroyed the entire solar system.

SG-1 also found a ZPM in Egypt which had previously belonged to the Supreme System Lord Ra. This one was used by the Crew of the Daedalus to arrive in Atlantis in only four days. Then it was used to shield Atlantis from A Wraith assault, and to trick them into believing that Atlantis was destroyed by a Nuclear warhead. This ZPM was depleted when to allow an alternate Rodney McKay to return to his universe.

When the Asurans attacked and occupied Atlantis, they brought three ZPMs to power the city. Atlantis 1 was able to destroy the Asurans and acquire the ZPMs. Two were sent back to Earth to protect the planet from an attack by the Ori. On the episode "The Road Not Taken" an alternate Earth never found Atlantis and therefore had their ZPM almost depleted from an Ori attack.