It seems to be very common to not understand, or misunderstand, the difference between power (watts) and energy (watt-hours). Even amongst technically-minded people who should know better.
A respected UK newspaper once printed a dramatic article claiming "20 new nuclear power plants" would be needed to power electric vehicles in the UK. This was nonsense and all based on confusing the estimated energy use of an EV fleet (in GWh) for instantaneous power (in GW).
They did publish a tiny sheepish apology several days later[1], and changed the online version of the article, but the damage was done and the claim still gets repeated today.
They're measuring the same thing. Except a joule is one watt-second, which is an inconveniently small unit when talking about large energy storage like an EV battery.
It would be like road signs measuring distances between cities in inches.
Besides, energy has long been accounted for in hour-based units. Your power bill, for example. It's just easier to use those same units when thinking about storage, rather than rebasing everything around seconds.
I know that they are both measuring energy. It's just that Watt is usually defined as Joule / second, so Joule seems more fundamental.
> They're measuring the same thing. Except a joule is one watt-second, which is an inconveniently small unit when talking about large energy storage like an EV battery.
That's what we have SI-prefixes for.
A Watt-Hour is also pretty small. We usually use Megawatt-hours or so. Using Giga-Joule instead wouldn't be too much of a difference.
> Besides, energy has long been accounted for in hour-based units. Your power bill, for example. It's just easier to use those same units when thinking about storage, rather than rebasing everything around seconds.
A respected UK newspaper once printed a dramatic article claiming "20 new nuclear power plants" would be needed to power electric vehicles in the UK. This was nonsense and all based on confusing the estimated energy use of an EV fleet (in GWh) for instantaneous power (in GW).
They did publish a tiny sheepish apology several days later[1], and changed the online version of the article, but the damage was done and the claim still gets repeated today.
[1] https://twitter.com/dpeilow/status/831717762259099648