Soul-Powered Engine

The use of a human soul as energy to power a type of Applied Phlebotinum. May Overlap with Powered by a Forsaken Child. See also Haunted Technology.

Anime and Manga

 * In Tengen Toppa Gurren Lagann, the Spiral Energy can do pretty much anything and it's the "scientific" representation of a person's soul.
 * Evangelions in Neon Genesis Evangelion are powered by souls, basically making them 3 human-like beings in one (which is definitely a problem sometimes). Typically they are the soul of the pilot's dead mother (also weird).
 * Psyren has Amagi Miroku using the life force of every living thing that dies as his power source.
 * Used in both continuities of Fullmetal Alchemist, however, it varies on its "Requireed fuel" and source, in the Brotherhood. The Philosophical Stone the requires Souls as it's creation Material/Fuel, and it is obtained through an alchemic transmutation gathering the souls of people within the Transmutation Circle Radius  while in the first Anime, it can be obtained in a similar way (and the one created there "just" required one whole town for it's creation.
 * In Puella Magi Madoka Magica, the magical girls' magic gems are
 * In the Mobile Suit Gundam side story The Blue Destiny, the super system EXAM is powered by the soul of a trapped Newtype girl named Marion Welsh, trapped there by its creator who feared Newtypes as a whole.

Literature

 * The Screwtape Letters: Demons work hard to tempt humans to be damned to Hell for the entirely practical reason that souls are demons' food.
 * The premise of an entire novel, The Gasp by Romain Gary. A scientist discovers a way to trap and harness 'something' that's released when people die, but being an atheist he refuses to believe it could be a "soul".
 * The metal killing machines in the Protector Of The Small series use the souls of children to power them.

Live Action TV

 * Season Six of Supernatural has the angel Castiel trying to garner 50,000 souls to power some sort of Angelic Nuclear Bomb.
 * In Torchwood, Death is said to have needed thirteen souls to walk the Earth permanently.

Tabletop Games

 * In Warhammer 40000, the God Emperor of Mankind is kept alive thanks to the daily sacrifice of untold numbers of psykers, allowing his spirit to continue lighting the Astronomican without which interstellar travel is impossible.
 * GURPS Technomancer. The Soul Burner Gestalt is a necromantic device that converts the souls of sacrificed human victims into magical energy.

Video Games

 * In Fall From Heaven, there's the 'Soul Forge' Wonder, an unholy engine that uses souls to speed production. In game-terms, this means that any unit that dies within a 1-square radius of the city, is added to its production (enemies and friends alike). If combined with Mokka's Cauldron - a Wonder that causes any unit that dies in the city to immediately be reborn as a Demon - a city can become essentially impossible to conquer, spawning units faster than you can kill 'em.
 * Used periodically in the Final Fantasy series.
 * Final Fantasy VII had the ShinRa and it's mining/extracting/whatever of "Mako Energy". Turns out that "Mako" comes from the "Lifestream", which is essentially a soup of human souls floating around on the inside of the planet.
 * In Final Fantasy IX, the Big Bad blocked the Well of Souls that takes the dead to the afterlife, leading to the backed-up souls piling up in the form of dense, magically potent Mist. Not knowing the source, people naturally began using this Mist as fuel for magitechnology and airships.
 * In The Elder Scrolls, you can trap the souls of your foes in soul gems and use them to enchant your weapons, technically making them soul powered.
 * Skyrim has technology and automatons built by the Dwemer and powered by soul gems, making them very literally soul powered engines.
 * In Asura's Wrath, Mantra is the fuel that powers the demigods' technology and grants them their superhuman powers. The demigods can draw Mantra from human prayer. It's also far more efficient to just drain human souls for it. Over the 12,000 years between their betrayal of Asura and his resurrection, the Deities have gathered trillions of souls' worth of Mantra.

Web Comics

 * Sluggy Freelance had that Haunted House that turned out to actually be an ELEVATOR TO HELL, with GHOSTS IN THE GAS-TANK! (Quoted verbatim.) Essentially, a number of captured spirits were used to power a spell that would open a gate into hell - and back - in order to provide a magician with an escape-clause from his Deal With The Devil.