Thanks for writing Pat. I appreciate your sharing the impression of MacKay's book and agree, with you except where I think MacKay has a point in claiming that: Energy consumption is power. Energy production is power.
That is correct. This is why: Energy, as the AMOUNT of it, is energy producED and it is indeed in J. But energy producTION is power because it implies a continuous process that involves time. In other words, energy produCED in 2007 is in joules but the energy producTION in 2007 is in watts. In yet another words, 100 EJ and 3200 GW both represent energy usage in the U.S. The 100 EJ is the energy consumed in the U.S. in 2007, the 3200 GW is the (average) energy consumption in the U.S.in 2007. The wording of the leading sentence determines if J or W is appropriate. Now there are two points here: It is better to write: The (average) power consumption thru 2007 was 3200 GW. I would word it that way, but the esteemed Prof. is not wrong saying it his way. Obviously, his way may cause confusion. And his kWh per day is silly as a base for comparison and the reasoning for it is medieval. The second point brings forth what I wrote earlier: Most of the climate and energy debates are about POWER because they deal with the amount of some kind of energy PER year, per day, per hour, etc. For conversions between the two common ways to express power consider that 1 GJ/y = 31.7 MW and 1 W = 31.5 MJ/y. His silly 1 kWh per day = 42 W In summary, the Prof. adheres to my long-standing recommendation for using power for the energy related comparisons but he should have worded his sentences better and stick with W. The joule per time times time is ..... (I don't want to repeat myself). Look again at how I compared the energy consumpTION of the years 1997 and 2007 in the U.S. in the tables on the last page of the attachment Ar-Energy-full.doc sent a few weeks ago. Stan Jakuba
