Because most things like this are measured in average power per year and it is useful for comparison. Different technologies produce energy at different rates. Solar, only when the sun is up. How would you compare it to wind which has different rules?
Taken to an extreme, consider some hypothetical new technology that produced 50 Gigawatts of energy, but did it in a second and then took a year to recharge before doing it again. Would it be more useful to say it had a 50 Gigawatt capacity or that it provided 50 Gigawatts of power per year when trying to compare it to other technologies?
Edit: I hope nobody would use my hypothetical technology… Boom!
50 GW for 1s is 50GJ. If that’s the energy delivered in a year then the average power is 1.584 kW. As long as your power plant lasts a few years or more (and you can actually put that energy onto the grid), the average power is a useful quantity to compare against any other power generation. Saying the average is over a period of a year doesn’t express anything about the variability of the power; just like saying your power plant could power a single electric heater running continuously, for a year, a decade or whatever period you like.
Power per unit time is kind of nonsense. It expresses an increase or decrease in power. Energy per unit time is power and is how we typically rate things that make or consume energy.
Because most things like this are measured in average power per year and it is useful for comparison. Different technologies produce energy at different rates. Solar, only when the sun is up. How would you compare it to wind which has different rules?
Taken to an extreme, consider some hypothetical new technology that produced 50 Gigawatts of energy, but did it in a second and then took a year to recharge before doing it again. Would it be more useful to say it had a 50 Gigawatt capacity or that it provided 50 Gigawatts of power per year when trying to compare it to other technologies?
Edit: I hope nobody would use my hypothetical technology… Boom!
50 GW for 1s is 50GJ. If that’s the energy delivered in a year then the average power is 1.584 kW. As long as your power plant lasts a few years or more (and you can actually put that energy onto the grid), the average power is a useful quantity to compare against any other power generation. Saying the average is over a period of a year doesn’t express anything about the variability of the power; just like saying your power plant could power a single electric heater running continuously, for a year, a decade or whatever period you like.
Power per unit time is kind of nonsense. It expresses an increase or decrease in power. Energy per unit time is power and is how we typically rate things that make or consume energy.