Howard, We already have *good “units”* they are the Units of the International System of Units (SI)! Having “lots of units” is a handicap. Using many units for each and every (or for only a few) quantities males comparisons difficult! This is the point that Stan tried to make in his preference for power. specified only in watts (W) and not in horsepower.
Gehe Mechtly. On Apr 10, 2016, at 4:17 PM, Howard Small <howard.p...@comcast.net<mailto:howard.p...@comcast.net>> wrote: I like having lots of units. It is a little like having lots of languages or like the Eskimos having lots of words for snow. We need a good unit for human power that individuals could use for themselves. Then we could appreciate how it is getting old. Or we could appreciate how ridiculous it is to have a 300 horsepower car. We are losing all sense of power and energy in today’s world. Part of the problem is not having good “units”. On Apr 10, 2016, at 4:21 PM, mechtly, eugene a <mech...@illinois.edu<mailto:mech...@illinois.edu>> wrote: Good reasons for your preference for power, Stan! Your reason I like best is that there are many fewer units in circulation for power (You select only one, watt) than for energy, (You cite four.) and for time (You name six.) and the difficulty of making comparisons is reduced. *Unnecessarily many* possibilities are avoided. Fewer comparison errors are likely. Gene. On Apr 9, 2016, at 4:13 PM, Stanislav Jakuba <jakub...@gmail.com<mailto:jakub...@gmail.com>> wrote: Here are reasons for the preference: Expressing power values in watts, rather than in the units of energy and time, has the advantage of eliminating the confusion that results from the existence of multitude of units for energy (J, Wh, cal, Bty, ......) and for units of time (hour, day, month, week, year, minute, .....). That can make comparisons difficult, confusing and conversions may introduce errors. Furthermore, the unit of time is often not expressed at all as is commonly done in, among others, the DOE documents. As for the unit watt itself, it was coined to eliminate (for reasons obvious to most USMA) all the prior power units such as the hp or the ton (of ice). There is no doubt that using only one unit for a physical quantity improves communication and helps eliminate accidents/injuries/misunderstandings/errors. It is a sad state of our education, on all levels, and text books, that one meets engineers who: - try to convert kW to kWh (it is impossible) - consider W a unit of power and kW a unit of energy - claim to pay in their utility bills for kW (instead of kWh) - are unable to convert Wh to SI (J/s x 3600 s = 3.6 kJ). Metric Today had an article about this a long, long time ago. Perhaps I'll attach the manuscript. Yah, here it is. Stan Jakuba On Sat, Apr 9, 2016 at 11:16 AM, mechtly, eugene a <mech...@illinois.edu<mailto:mech...@illinois.edu>> wrote: To Howard (Small), Here is the answer to your question: Stan prefers discussing Power in watts (W) or in its SI decimal multiples (e.g. GW) averaged over a specified or implied period of time rather than energy in joules (J) or (e.g.GWH), processed over that that same period of time. Either method can be accurate in SI Units of Measurement!, and is acceptable as a matter of preference. Eugene Mechtly. On Mar 29, 2016, at 5:23 PM, Howard Small <howard.p...@comcast.net<mailto:howard.p...@comcast.net>> wrote: Why does the graph say GW instead of GWH? Howard On Mar 29, 2016, at 2:17 PM, Stanislav Jakuba <jakub...@gmail.com<mailto:jakub...@gmail.com>> wrote: Friends: Attached is the graph showing the output for the requested non-renewable energy sources. With it, at the bottom on the same page, is the earlier graph for wind & solar. It is drawn on the same scale thus making a comparison between those two groups of sources easy. Both graphs show the history of only one form of energy - electricity. What is the chance that W&S, the only grow-able sources, will ever provide the ~400 GW shown in the upper chart? Or the ~3200 GW the U.S. is consuming overall? Unlikely, isn't it. That hopelessness can be seen better yet in the Prof. Brownridge's charts. Click this link Dennis Brownridge, U.S. Energy Sources (charts 1-8)<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.dropbox.com_s_9jdbfnvbfzj0xt8_U.S.-2520Energy-2520-2526-2520CO2-2520Emissions-252C-2520Charts-25201-2D8-2520-2528Sources-2529.pdf-3Fdl-3D0&d=BQMFaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=BpxbfWo0gcPQHL0R58p0D96tVlzZlsjR_iWGK6ETi80&m=YzY_J_-3Qk_r724SMhYMAjH5-Hsjn442Sb_YHc5bpr4&s=Tqw8sFP44WvJVNfHCdvsknk11AkyoTayxKSU8UmgvAg&e=> and see plate # 5; it illustrates the above traces in vivid colors. Notice how easy comparisons among documents are with SI units in both illustrations. Recalling the earlier chart that had all the renewable sources shown it may amuse you to read that Dep't of Energy values the traces as follows: Between 2005 and 2015, electricity generation from solar increased 48 fold, from 550 GWh to 26,473 GWh. Biomass increased 18.3% from 54,277 to 64,191 GWh, and geothermal increased 14.1% from 14,692 to 16,767 GWh. True, but how much is 14 % of very little? And 48 times more of nothing may not be all that much either. But it sounds good. The drop in hydro better be not mentioned. Viewing the trends confirms my 40-years old conviction that If mankind were to rely mainly on renewable sources for energy, as it did 2-1/2 centuries ago, starvation and social unrest would result due to energy skyrocketed cost, unreliable delivery and population growth. Being involved in the clean renewables since the '70s, I remember that effort sparked by proclamations such as these two examples: In 1973, Walter Morrow, Associate Director of Lincoln Laboratories at MIT predicted that the US would generate between 750 to 1500 GW from direct solar by year 2010. In 1978, Ralph Nader predicted “Everything will be solar in 30 years.” Stan Jakuba <Graph for Me.pdf> <Graph for Me copy.pdf> <Energy & power for MT2.doc>
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