"Energy is the currency of the future."—CEO Nwabudike Morgan, Sid Meier's Alpha Centauri
Some works of science fiction and fantasy have societies or groups that use energy as a monetary unit. This is not about what the Enron Corporation used to do, buying and selling energy; this trope is about cases when the energy or energy source itself is the money. In some cases, an energy crisis is equivalent to an economic recession.
In economics, this would be a form of Commodity Money - it serves as currency but can serve another function.
- Energon in Transformers is used as currency in parts of the galaxy as well as the primary source of power for the bots and their weapons.
- In the movie In Time, each person's 1 year of life (after they reach 25 years old) is their currency. People are paid in extra life time and pay with the same. When the account runs out, they die immediately.
- In the Void Trilogy by Peter F. Hamilton, the race of 'Higher' humans use Energy and Mass Allowance (EMA) as a kind of currency. The majority of Highers live non-corporeally, but their EMA can be pooled as part of a 'Faction' or in smaller groups to effect change in both the physical and simulated realms.
- The Red Mars Trilogy used calories of heat as the basis of the Martian economy.
- In Tim Powers' Dinner At Deviant's Palace, the dominant currency in a Scavenger World L.A. is a high-proof distilled alcohol: useable as a fuel, a disinfectant, or as plain ol' booze, hence much in demand.
- Wizards in the Young Wizards series can use energy as payment at The Crossings, although presumably this is only while on errantry.
- It's only subsidized if they're on errantry. They could still pay using their own personal energy, but it might not be worth paying for lunch only to be hit with a lunch's worth of energy drain.
- In Bruce Coville's Rod Allbright series, a.k.a. Aliens Ate My Homework, the intergalactic currency units are energy credits. The captain even refuses a detour since the energy required would use more energy than his crew makes in a year.
- At the end of Making Money, Lord Vetinari and Moist von Lipwig consider putting the Ankh-Morpork economy on the "golem standard", such that dollars could be exchanged for a set amount of labor by a municipal golem.
- In the Warlock of Gramaraye series, the interstellar government's currency is the "kwaher" or kilowatt-hour.
- The Council Wars series starts out this way, with there being so much cheap power that no one really needs to use it as a currency. It's just easier than trying to find something that both parties will find valuable. After the Fall, they have to come up with a completely new economy.
- In H. G. Wells' The Shape of Things to Come, the World Transport Union creates the "air dollar." (Spending one air dollar would allow you to transport one kilogram one kilometer in the WTU's aircraft, or something like that.) Eventually it's replaced by the "energy dollar," which is a straight play on this trope.
- One of the half-dozen or so currencies available in Star Trek Online is the "Energy Credit".
- Wizards of the Coast's old The Primal Order RPG supplement suggested the possibility of a divine economy running on primal base—the less temporary form of divine power.
- Exalted has one of the most basic versions of this—employees of Yu-Shan are paid in ambrosia. That is, little coins of the most delicious food ever. It's mentioned that a common problem amongst new bureaucrats is the literal consumption of their entire operating budget. In addition, ambrosia can be transformed into...well, pretty much anything, really. This is generally the use toward which it is expected to be put—why eat it when a single coin could give you more resources than the mayor of a small city?
- White Wolf's Mage: The Awakening uses Tass, solidified magical energy. The core book suggests that a single unit is worth around $10,000 (or at least, retails for around that price). Partly justified in that most Mages can get money easily, even large sums. It still seems very expensive considering how easily most mages can get said energy itself (normally).
- In a similar way, though more developed, Atlas Games' Ars Magica has Vis, again a form of solidified "magic power". The vis (latin for power) is essential to cast powerful ritual spells, healing wounds and making spells permanent . Control and trade of vis is the basis of the economics of magic covenants. It's exchanged for favors, support, access to libraries and in places where it's scarce - such as the Roman Tribunal - for enormous amounts of money. The vis "tainted" by the power of the Techniques (magic language "verbs") is much more valuable than that which is linked with Forms (names).
- It's worth noting that White Wolf have a historical connection to Ars Magica, and concepts from it have found their way into both Worlds of Darkness.
- The Mystara boxed set on Glantri introduced a currency, used among that nation's wizardly elite, consisting of coins imbued with magical energy. The holders of such coins could power spells with that energy, allowing them to use more spells per day than would otherwise be possible.
- In Bruce Heard's Voyages Of The Princess Ark article on Limbo, the Mystara-cosmology's realm of the dead, souls there could use their own residual life force as currency.
- Startopia not only has energy as currency, but also needs the same kind of energy to power facilities. Spend too much, and things will shut down.
- Extra energy could also be procured by recycling stuff, making the Polvakian Gem Slugs, who excreted the high energy content Turdite, the richest creatures in the universe. That's right, they literally crapped money.
- Sid Meier's Alpha Centauri has energy credits, the more energy collecting facilities, the higher the income.
- Notably, the main energy facilities are solar collectors (which produce more energy based on elevation—the higher up you are, the more energy you produce) and tidal harnesses: both clean, renewable energy. This has two reasons, one Watsonian, one Doylist. On the Watsonian side, this is partly necessity—Planet has virtually no fossil fuels to speak of. On the other hand, the Doylist reason becomes obvious when considering the third method of gaining energy, the thermal borehole: it produce massive amounts of energy, but is likely to attract the wrath of Planet if you're not careful.
- Transarctica centers on a train/base that runs on two kinds of coal, lignite and anthracite. Since the world is in the grip of a new ice-age and heating is a premium, lignite is used a the main currency. Anthracite is more energy efficient, less volatile, but more rare, if that runs out, you'll have to fuel your engines with cold cash. If you're in a major hurry, throwing some cash on the boiler may be worth it.
- Margin from the freeware adventure game, A Second Face is used as both currency and as a fuel source.
- The X Universe games have energy cells as the subsidized basis of the economy. However, while energy cells power production and serve as the basic foundation of the games' dynamic economy, they aren't actually the main currency, which is just the humble Credit.
- Metal Fatigue has Metajoules as the only resource. Metajoules are aquired from solar and geothermal energy and can only be stored in a finite amount. Justified in that in the far future where the plot happens, direct matter-energy conversion is possible so anything can be manufactured from anything if the raw material is converted into energy then that energy is converted into the intended product.
- In Shin Megami Tensei: Strange Journey, Macca is the currency of demons, and its energy qualities are taken literally - you use it to power healing devices in the field, and the amount of Macca you pay for items and healing on the ship are justified as being the energy it takes to materialize the items/power the sickbay.
- Present and accounted for in Spiral Knights. Players need energy to craft items and go through dungeons, so needless to say, it's in high demand. The player regenerates 100 energy over time, but there is a huge economy for Crystal Energy which can be used whenever they want, and has to be purchased with real world money or from other players.
- Souls are basically energy in Demon's Souls and Dark Souls. You can use them upon yourself (as experience points) or use them to buy things from merchants (who also presumably use them upon themselves to keep them alive).
- Within NationStates, several active futuristic nations use energy at least partially as a currency, or use it to back theirs.
- Schlock Mercenary has a variation - power economy. Antimatter itself apparently isn't very expensive, but ability to use it efficiently for power and gravitics requires post-transuranium alloys, which in turn require lots of energy to produce, which makes it a large part of the main bottleneck for the current galactic civilization (the other part is ability to actually work this stuff, because that's what limits the size, and Bigger Is Better). Earth got some on a loan when joining the community, while Ob'enn and Kssthrata from Tause System found an unattended chunk of this stuff with total mass in planet range floating around (left by the ancient Oafans) and of course started a war over it - which is why military-wise the Ob'enn are in the high tier, but their reach vastly exceeded their grasp.