Because this is for utility companies where the value of the rate of discharge might be even more important than the energy capacity? A quick look at their sit

Because this is for utility companies where the value of the rate of discharge might be even more important than the energy capacity? A quick look at their site shows "battery power capacity" is measured in watts, whereas "battery energy capacity" is measured in watt-hours. https://www.eia.gov/todayinenergy/detail.php?id=51798 https://www.eia.gov/todayinenergy/detail.php?id=51798