Metaphysical Fuel

"Love is a very powerful force. Even more so when it's focused into a coherent beam of destruction. Every time I cast Hadoken, it siphons away some of the love in the universe. I'm not sure how much, but I'm given to understand the divorce rate goes up with each blast."

- Black Mage, 8-Bit Theater

Some of the softer Science Fiction has its new technology powered by something rather...different to plain old electricity, nuclear power, Phlebotinum, Functional Magic, or petrol.

Depending on the series, this can be either for something Powered by a Forsaken Child, or a source that gives power to no (or little) ill effect.

Just to be clear, if the fuel source exists in Real Life, it isn't an example. Mysterious new substances and energy sources also don't count.

Compare Magitek, which is usually fueled this way.

Anime and Manga

 * Zearth and the other robots in Bokurano require the life force of the pilot after being used. Because of this each team has 14-15 pilots to go through after the others die.
 * In Fullmetal Alchemist, the Philosopher's Stones that allows alchemists to bypass the law of Equivalent Exchange are created from

Tabletop Game

 * The Chancels of the Player Characters in Nobilis require the deaths of one hundred human beings (or equivalent sacrifice) to be created.
 * In Warhammer 40000, the Emperor's Golden Throne is powered by 1,000 powerful souls per day.
 * And not just any soul. Only the best, most talented psychic souls will do.
 * Lifejammers in the Spelljammer D&D setting worked like this.

Video Games

 * The Persona and Shadows of Persona 3 are powered and personify human emotions. Persona themselves are summoned by shooting a character in the head with a gun that fire pure psychological trauma.
 * The Mako and Materia of Final Fantasy VII are fueled by the life force of the planet, with mako being especially unhealthy to deal with. Square and SquareEnix in general is a big fan of this. Final Fantasy VIII has Guardian Forces powered by consuming memories, most technology in Final Fantasy IX is ultimately powered by, and Espers are essentially magic through crystalized Demihuman souls.
 * In game, the explanation for the Guardian Forces is a bit different. They need room inside a person's head to be able to work with them. The neurons they take over happen to be the neurons that keep your memories. Probably more benign than if they'd take your visual cortex or primary motor cortex.
 * In Tales of Symphonia exspheres are "grown" on human slaves, at the cost of turning them into big slimy monsters. Lloyd's exsphere contains the soul of
 * Breath of Fire IV has a particularly horrific example in the Carronade; aforementioned Carronade is literally a Fantastic Nuke powered by Metaphysical Fuel that is generated via the Cold-Blooded Torture (to the point of suicidal despair and insanity) of those who have close connections with the intended Ground Zero. (Yes, you're reading this right--it's a Fantastic Nuke that not only uses tortured Forsaken Children as its Metaphysical Fuel but explicitly operates on the theory that Love Hurts. In fact, the deeper the love, the deeper the metaphysical radiation poisonong goes.)
 * Oh, and the one time where the use of the Carronade was depicted (rather than its aftereffects) was when the Evil Empire literally used the girlfriend of its King in the Mountain and God-Emperor as Metaphysical Fuel for the Carronade because she was his girlfriend and was in love with him (this merely got aforementioned God-Emperor royally pissed off and threw him over the Despair Event Horizon into Woobie, Destroyer of Worlds territory). The Comic Book Adaptation in particular depicts the latter in especially tragic fashion.
 * You build your equipment in Strange Journey out of bits and pieces of demons. This can range from the relatively mundane ("Reaper Knife", "Tyrant Glacier") to the... unnerving ("Haunt Rib", "Dragon Eyeball").

Web Comics

 * Eight Bit Theater: Black Mage's Hadoken converts love into a beam of destruction. Not in the "powered by the goodwill of his loved ones" sense either, divorce rates go up every time he casts it.

Western Animation

 * Dr Thadius Venture of The Venture Brothers invented a booth that will let the user experience their most intimate fantasies as though reality. Nice guy necromancer Dr. Byron Orpheus discovered to his horror that the machine was powered by the soul of an orphan.
 * The Tick (animation) TV series once featured a race of aliens whose ship ran on fear. Their own fear, given that they're the most timid and cowardly race in the galaxy. Second-most timid and cowardly, that is. They're topped by Arthur, who is by nature so anxious and skittish that when they hook him up as the ship's fuel source, the thing reaches speeds the aliens didn't even realize were possible with their system.

Animated Films

 * The monster world in Monsters, Inc. is powered by children's screams.

Anime and Manga

 * Gunmen in Gurren Lagann are powered by Spiral Energy, which is generated by the pilots' fighting spirit. They can also be powered by more conventional means, since
 * However, Spiral energy subverts the "little to no ill effect" part of the trope:
 * The titular flying vehicles in Simoun are powered by the souls of their pilots uniting in common goal and desire...which just so happens to expressed by the two pilots kissing.
 * In Eureka Seven, Humongous Mecha fly on ! It Makes Sense in Context, really.
 * The G-Stone in GaoGaiGar is powered by courage!
 * "Stealing GGG's will to fight! Turning me and GaoFighGar against them! Splitting us up across the world! It's all because you were afraid! Afraid that the G-Stone would transcend the power of the Loud G-Stone! This is the power born from courage!!"
 * Compare and contrast: The Character Guardians from Shugo Chara are powered by their owner's will to change their own personality, the exact opposite of a persona. (I haven't seen a more perfect cause for a crossover fanfic in ages)
 * The Lambda Drivers in Full Metal Panic! are powered by the anger of the Humongous Mecha pilot. Good for Determinators and Ax Crazies.

Comic Books

 * The Green Lanterns and related corps are powered by the emotions of all living things. The GLC itself is fueled by Heroic Willpower; the others are Unstoppable Rage, Greed, Fear, Hope, Compassion, and The Power of Love. There is a danger for several corps, however, that the emotion they wield will overpower them (for example, the Star Sapphires that use love energy are subject to Love Makes You Crazy).

Literature

 * The Hitchhiker's Guide to the Galaxy has several.
 * The Heart of Gold is powered by improbability.
 * The Bistromath is powered by the uncanny mathematics involved in splitting the bill in a restaurant.
 * An alien race designed a ship powered by bad news, the one substance in the universe faster than light. But they never worked very well and no one wanted them around, so people stopped using them fairly quickly.
 * The Intention Craft in His Dark Materials is powered by the user's intentions.

Tabletop Games

 * Dwarven asteroid/ships in Spelljammer are made to move by the cumulative determination and work-ethic of their occupants, channeled through magic anvils.
 * In Warhammer 40000, the Orks' vehicles are powered by the Orks' belief in them. This leads to red vehicles flying faster simply because they can.
 * The ANIMa of Bliss Stage are powered by Intimacy.

Video Games

 * Each of the main character's many Persona in Persona 3 are powered by and reinforced by the strength of related relationships he has.
 * The Persona in Persona 4 are powered by the need of an individual to face life's hardships. They only have superpowers when battling enemies, but gaining a persona results in a dramatic change in the character's personality by the time their social link is maxed out (.
 * The psychic powers each Player has in The World Ends With You are powered by imagination, and those who survive the Game are often recognized as geniuses by other people. The game's resident Mad Mathematician is an incredibly powerful boss, and he is stated to have huge amounts of imagination.
 * Space Channel 5 has giant lasers and floating platforms powered by "dance energy".

Webcomics

 * Goats wins this one hands down.

Western Animation

 * In an episode of The Simpsons, Ed Begley Jr. designed a go-kart powered by his own sense of self-satisfaction. It worked very well.

Other

 * It's implied that Sidhe magic in Barry Blair's comic Elflord is powered by Yaoi.