Consider two electric utilities. Over the course of a year, the larger one sells more joules (or kilowatt hours) of electricity than the smaller one: *If the larger one shuts down and the smaller one keeps running, it will eventually outproduce the large one *If the both keep running, the year, or other time element, is the same for both of them, one can deliver more energy for the year only by running at a higher (annual average) power level for the year.
The utility does not produce a given amount of energy and stop. The only meaningful way to talk about the scale of the utility is energy delivered over some period of time; energy per unit of time is the definition of power. Regardless of the exact details of how the grid is operated, plants are scheduled in advance to produce at target power levels, and reliable plants meet those schedules. Electric plants are managed to power targets and energy is what accumulates by integration of that power over time. I don't remember or care to revisit all the details on intensive vs exetensive, but time "flows" at the same rate for all systems. I don't think dividing an extensive variable by time makes it intensive. ________________________________ From: "[email protected]" <[email protected]> To: U.S. Metric Association <[email protected]> Sent: Thu, January 13, 2011 4:28:01 PM Subject: [USMA:49500] Variables (Intensive vs. Extensive) Power is an intensive variable (J/s)....Energy is an extensive variable (J). Temperature is intensive (K)..............Heat is extensive (J). Speed is intensive (m/s)....................Distance is extensive (m). Density if intensive (kg/m^3.............Mass is extensive (kg). Rate of flow is intensive (kg/s)..........Accumulated flow is extensive (kg). Rate of snow fall is intensive (mm/s) Accumulated snow depth is extensive (m). All rates are intensive........................Accumulations are extensive. Intensive variables are never "consumed." ---- Original message ---- >Date: Thu, 13 Jan 2011 08:15:49 -0800 (PST) >From: "John M. Steele" <[email protected]> >Subject: Re: [USMA:49492] Re: Screen size conundrum >To: [email protected], "U.S. Metric Association" <[email protected]> > John states: I will argue that power is consumed (and wasted). Mechtly counters: Rates are never "consumed." John states: > I will further argue that speed consumes gasoline. > The amount of gasoline to go a given distance varies > with speed. Mechtly agrees with these two indisputable statements. > For electrical energy usage, it makes a lot of sense to > look at instantaneous power (which is consumed... Mechtly claims this statement is nonsense.
