7 ms·
I think he means the capacity will be 40 GWh / year = 4.56MW.
by mh8h 4y ago
I think he means the capacity will be 40 GWh / year = 4.56MW.
- atwood22 4y agoSorry I’m not sure I understand. Watt hour is a unit of energy. Energy can be stored. They’re making batteries that store energy. A Watt is a unit of power. They’re not making power. So after a year of making batteries, they will have produced exactly 0 Watts. I guess in that sense you can measure their (power) output in Watts: they produce 0 Watts. I think the confusion is that the unit of their product is not GWh. It’s (GWh of capacity) which is not the simple product of Watt and hour)
- jupp0r 4y agoHow much battery capacity are they producing per day? Impossible to tell from the article. I’m relatively sure that the period of time the specified capacity is produced in is one year. You can divide the hours in GWh by the year time span and the time units cross out. The unit is Watt, but the physical quantity it’s describing is arguably not power but energy capacity production rate or something similar. There’s no 1:1 mapping between units and physical quantities, just think about specific impulse in rocket engines being quantified in seconds.
- atwood22 4y agoThe unit is not GWh. It's "GWh of storage." It's ironic that this thread started with you lamenting that units are used incorrectly.
- jupp0r 4y agoThe unit is GWh, the physical quantity it describes is “energy storage capacity”. Those two are not the same. Take this example: Unit: second, physical quantity: could be things like “time”, “specific impulse”, “distance” (light-second), etc. Many physical quantities can be measured in seconds.
- adament 4y agoIs it really true that you can measure distance in seconds? I think light-seconds are different units from seconds hence why they measure distances, similar to how Watt-hours and Watts are not the same unit. If a second was a measure of distance then speed would be unit-less (second / second) as opposed to the speed of light which is light-second / second ≈ 3e8 m/s.
- jupp0r 4y agoYou are right, light seconds don't fit in well. My point still stands, you can't really know what physical quantity is measured just from looking at the unit alone, that's now what units are made for.
- toxik 4y agoYou can still divide GWh of capacity by a year and get GW of capacity, ie the instantaneous production rate of capacity.
- atwood22 4y agoNo you cannot. Watt hour is a unit for energy derived by applying power over time. That’s why when you divide by a period of time you’re left with power. The unit “GWh of storage” is a complex unit that’s not easily broken up. When you divide by time you get a new unit, “GWh of storage per unit time”
- jupp0r 4y agoYou are conflating two different concepts here. One is "unit" which is a measure of a physical quantity (ie "GWh"). The second is the physical quantity itself ("battery storage capacity"). The relationship between the two is that a unit can be used to quantitatively describe a physical quantity ("5 GWh of battery storage capacity"). Physical quantities like "battery storage capacity" can usually be quantified in different units which can be converted to each other ("5000kWh = 5GWh = 1.8 * 10^13 J"). The unit itself ("GWh") doesn't describe precisely what physical quantity is being measured. It could be mechanical energy stored in a flywheel, the total heat output of a chemical reaction, battery storage capacity, etc.
- atwood22 4y agoYou’re fundamentally misunderstanding the units. I don’t know what else to say. “Watt hour of storage” is not the same as a Watt hour. You can’t divide by time to get power. That should be obvious.
- jupp0r 4y ago"Watt hour of storage" is not a unit, it's the physical quantity "storage" quantified by the unit "Watt hour", ie the combination of the two.
- yazaddaruvala 4y agoWe really need to rename these things to be based on Joules instead. A lot more intuitive. This battery stores X Joules. 1 J = 360 kWh This battery releases Y Joules per second. 1 J / s = 1 Watt