The Invisible Trillion
The Energy Question, Honestly
What a Kilowatt-Hour Actually Is, and Why Nobody Will Tell You
Most of what you have heard about the energy cost of the internet, of AI, of data centers, of chips, is either exaggerated or too vague to be useful. This is not because people are lying to you. It is because energy is invisible, and when things are invisible, humans get the numbers wrong.
This chapter is going to give you the numbers. Some of them will be smaller than you expect. Some of them will be bigger. A few of them we don’t actually know, because the companies that would know aren’t telling anyone, and that itself is part of the story.
By the end of the chapter you should be able to do something that, strangely, almost no adult can do: look at a claim about the energy cost of some technology — a ChatGPT query, a streaming show, a Bitcoin transaction, a flight — and have a rough sense of whether the number is plausible, and what to compare it to.
The Unit
Before anything else, you need a unit. Otherwise the numbers are just shapes.
The unit is the watt-hour, abbreviated Wh. It is the amount of energy it takes to run a one-watt device for one hour.
A watt is small. An LED bulb is about 10 watts. A laptop at full tilt is about 50 watts. A microwave is about 1,000 watts, which is why we usually talk about microwaves in kilowatt-hours — thousands of watt-hours, abbreviated kWh. One kWh is one kilowatt running for one hour. It’s the unit your electric bill uses.
Here are some things it is useful to memorize, because once you have them in your head, every other number becomes legible.
| Thing | Energy |
|---|---|
| Phone charge (full) | 15 Wh |
| Laptop for one hour | 50 Wh |
| LED bulb for one hour | 10 Wh |
| Incandescent bulb for one hour | 60 Wh |
| Refrigerator for one day | 1,500 Wh (1.5 kWh) |
| One hour of Netflix on a TV | 100 Wh |
| One mile in an electric car | 300 Wh |
| One mile in a gas car | 1,100 Wh equivalent |
| One load of laundry | 2,000 Wh (2 kWh) |
| One hour of air conditioning | 3,500 Wh (3.5 kWh) |
| One cheeseburger (to produce) | 3,000 Wh (3 kWh) |
| One transatlantic flight, per passenger | 900,000 Wh (900 kWh) |
Take a minute with that table. The flight is worth staring at. One round trip from New York to London uses, per passenger, roughly as much energy as running a refrigerator continuously for a year and a half, or driving an electric car 3,000 miles, or leaving every LED bulb in a medium-sized house on for four years straight.
This is the context you need for every other number in this chapter.
All 19 chapters of The Invisible Trillion · Library · All courses