Phason pods were a type of compressed power cell. A single phason pod could power a starship for a whole day. Some phason pods were kept in the hangar bay in the spaceport of Kiria City on the planet Urbinia.
In an alternate timeline in which the Daleks launched the Harvest of Urbinia, Zoe Heriot used a molecular bonder to tamper with a some of the phason pods, making them more volatile. Steven Taylor objected, given the risk involved and the facts the pods may be needed for the evacuation, but Zoe used them to set an ambush. When three Silver Daleks forced their way into the hanger bay, the volatile pods were detonated, igniting fuel deliberately spilled across the floor. Intense flames engulfed the Daleks and destroyed them. (AUDIO: Daughter of the Gods)