“How much power does it consume?”

This has been a key question ever since I started work as a product engineer many years ago. Heck, back then we even published power consumption numbers, although we used I_CC as a proxy – we didn’t actually publish power, but you could easily do the multiplication with V_CC to get it. (Yes, this was bipolar.)

These days, the concept is even more important, what with all the focus on battery-powered whats-itses. But in deconstructing a lot of what’s going on now, there’s an interesting nuance coming to the fore: energy vs. power.

• Energy is a “thing.” It’s something physical that has a measurable quantity.
• Power, by contrast, is not a thing; it represents the rate of flow of a thing, namely energy.

This is more than just an academic difference. Batteries and fuel cells can store more energy than a supercapacitor can, but they release that energy at a slower rate than the supercap. So one is capable of higher energy capacity; the other of higher power. The distinction actually matters.

So I find myself tripping more and more over the familiar phrase, “power consumption.” Power isn’t a “thing,” so it can’t be consumed. Energy is a “thing,” and it can be consumed.

So “power consumption” makes no conceptual sense; “energy consumption” makes a ton of sense.

An electronic device consumes energy, but, from a practical standpoint, you can’t know the energy consumed until you know how long you’ve run the device. And you have to be able to serve up the energy to the device from your energy store at the rate the device expects, or else you’ll starve it. So “power” is ultimately involved as a critical device requirement; energy consumption not so much.

So if “power consumption” is off the table, “power requirement” seems a suitable replacement.

I will therefore labor to use either “energy consumption” or “power requirement” henceforth.

And no, I don’t expect the world to follow. (One of my many quixotic attempts to apply logic to language… like the perennial abuse of the plural of “die” and the silly overuse of @…)