Back To The Future’s Flux Capacitor Could Power Six Aircraft Carriers

In honor of Back To The Future Day, we figured out just how much energy it takes to power a 1.21 Gigawatt Flux Capacitor. You're going to need a lot of lightbulbs

(Photo: Terabass, Photo Illustration: Diana Quach/Vocativ)
Oct 21, 2015 at 6:34 PM ET

It’s October 21, 2015, the day when Marty McFly and Doc Brown famously drove a time traveling DeLorean from 1985 into modernity to save McFly’s future son from ending up in prison in Back To The Future II.

The DeLorean runs on a Flux Capacitor which (in addition to having its own Wikipedia entry) requires 1.21 gigawatts of power to operate. Now, we’re not here to damper your DeLorean dreams, but 1.21 GW is no small amount of electrical power. Put it this way—if you want to travel with the Doc, you’re going to need a lot of lightbulbs. Here’s a realistic estimate:

So…what’s in a watt? Watts are a unit of power, which tell us the rate at which electrical flow is produced or consumed. A complementary term is a “watt-hour”, which is a unit of energy (not power) that helps us measure how much work has been performed using the available watts. Electric companies charge you by the watt-hour; lightbulbs are sold to you by the watt. Watts remain fairly constant; watt-hours change over time.

For instance, if you keep a 60 watt lightbulb on for one hour, it uses 60 watt-hours of energy. Pretty simple. But if you keep that lightbulb on for two hours, the same 60 watt lightbulb will have used 120 watt-hours of energy.

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Let’s geek out. The Doc’s Flux Capacitor requires 1.21 gigawatts of power to operate. But how much energy is that? Well, it depends on how much time we spend doling out that power. Fortunately, we have the original Back To The Future, where the Doc uses a lightning bolt to jump start the DeLorean.

Lightning strikes can contain thousands of gigawatts of power, so it’s easily conceivable that a bolt of lightning could supply us with 1.21 gigawatts of power, but only over the course of about 50 microseconds (one microsecond is one-millionth of a second). Sure, that’s a lot of power but actually not a lot of energy. 1.21 gigawatts delivered in 50 microseconds is only about 60,500 Joules, or 14 kilocalories of energy.

Which is the amount of energy in…a cucumber.

But hey—if it works, it works. As Doc Brown himself once said:

This is the answer. It says here that a bolt of lightning is going to strike the clock tower at precisely 10:04 p.m. next Saturday night! If we could somehow harness this lightning, channel it into the flux capacitor, it just might work. Next Saturday night, we’re sending you back to the future!

See you there, Doc.