When they say their battery storage capacity is 15,000 MW, do they mean MWh? Because watts are time-independent, or rather, they're like speed to Joule's (watt-hour's) distance.
I struggle to understand why journalists consistently failed to use Wh as a unit of power. People generally can understand it because it is how they are billed and how appliances are rated.
Even on HN people will defend not using Wh because there is some grid or city in the USA that bills differently.
Battery storage is always measured in the amount of power that can be delivered (Watts). Secondarily it’s measured in the number of hours that power can be delivered (hours, which is almost always about 4.) To get MWh you multiply watts times hours. This is standard in the industry and has nothing to do with reporters.
Because American literacy in math and hard sciences has only declined over the decades since the post-Sputnik spurt that benefited my generation. Journalism as practiced today doesn't require scientific literacy or rigor, or at least, they are secondary to the purposes of the writers' employers.
Later, they say “lithium ion batteries only have 4 to 6 hours of capacity”, which again, what? But maybe that implies that the actual capacity rating is their “capacity” x 4-6.
Uh... "Wh" is not a unit of power. Watts are units of power. Watt-hours measure energy. Probably journalists are getting this wrong for the same reason you are.
Utilities are used using MW when discussing supply and demand. Because balancing that is critical. So power is what they care about when discussing grid connections.
The billing side and customers are concerned with total energy. So kwh.
Journalists typically don't know the difference. Which is why they list storage capacity in watts. They don't know any better and they don't care.
Far as I can tell multiply the watts by 4 hours to get watt hours.
sgustard|4 months ago
"Battery storage capacity grew from about 500 MW in 2020 to 13,000 MW in December 2024"
https://www.caiso.com/documents/2024-special-report-on-batte...
As another commenter notes, utilities are interested in "capacity on call" i.e. instant power generation.
teruakohatu|4 months ago
Even on HN people will defend not using Wh because there is some grid or city in the USA that bills differently.
matthewdgreen|4 months ago
bolangi|4 months ago
ericd|4 months ago
ajross|4 months ago
Gibbon1|4 months ago
The billing side and customers are concerned with total energy. So kwh.
Journalists typically don't know the difference. Which is why they list storage capacity in watts. They don't know any better and they don't care.
Far as I can tell multiply the watts by 4 hours to get watt hours.