> In many cases, > processes that had previously been economically uncompetitive due to > high energy costs became economical and crowded out previous > processes.
the odd thing is that the ratio of workers to total population in human societies seems to stay constant at about 1/3, despite all the technical changes. > ### how much do things radiate per unit area at the contemplated > ### temperatures? power/area for blackbodies goes as T to the fourth. stefan-boltzmann says 5.7x10^-8 W m^-2 K^-4. > Another alternative is to carry out energy-consuming processes deep > enough underground that the waste heat will take thousands of years to > reach the surface. before radioactive decay was understood as an energy (and heat) source, Kelvin had calculated an upper limit for the age of the sun and earth of 100 million years, based on their observed heat fluxes. that's a bit longer than 4004 BC, but still not enough time to be comfortable for evolution, or even for the currently observed geological processes to have always worked at the same rate. now, of course, we're looking at more like 4 billion years and have had more than enough time for both biology and geology to have produced the observed natural world. > ### Aren't there other, commoner ores of aluminum (corundum?) that > ### just cost more energy to extract? there's more Al in the earth's crust than Fe (third most common element in bulk composition) which makes sense, considering that the crust is all the light scum that floated to the top. > ### What's the current cost of fresh water? based on two year old ag pricing (and dodgy math?), it's only about 1 cent for 64 kg, here in relatively arid southern California. "[Fwd: The Costs of Making a DRAM Chip]" <http://xent.com/pipermail/fork/2003-January/016820.html> > ### What is the actual raw-materials cost of glass? How about after > ### it's made? if energy is free, materials should be cheap: glass is Si and O and some doping, and O and Si are the first two most common elements in the earth's crust. Ca for lime and Na for soda are #5 and #6, the elements just after Fe. (finding boron for lab glassware may be a bit more difficult) (Abundant crustal elements: O Si Al Fe Ca Na K Mg) > ### How hot do you need to > ### get granite to melt it? depends on pressure (and composition -- rocks are solutions) a pahoehoe lava (which is basaltic, not granitic, but seems like it would be more castable) seems to run about 1000C at the surface. > ### What are the numbers on waterjet? it's way spendy, but I don't know how much of that is because of consumables, and how much is to amortize the machine. > ### How about grinding? for my applications, relatively cheap, inefficient, and slow. with cheap energy, how about arc gouging? > ### How high is 3-D printing's energy cost? How substantial is the > ### decrease in raw-material cost? in general, I think 3-D printing's current niche is for those areas where it'd take way too much time to manufacture something some other way, not as a cost saving. For high volume parts, a little bit of engineering can go a long way towards reducing any scrap involved. (how much do computer "chips" owe to the "chips" that metalworkers made, by analogy with the woodcarvers before them?) > ### What is the actual fraction of U-238? I believe U is naturally over 99% U-238, and that 95% is about the right enrichment for reactors. "dope exponentialz [Re: India intercepted ...]" <http://lair.xent.com/pipermail/fork/Week-of-Mon-20030908/025487.html> > If you expect your power supply to decline dramatically in the future, > or to become dramatically more expensive (say, due to wars or > exhaustion of supply), it might make sense to manufacture solar cells > now, even using current technology, and continue to use them for a > long time. > > ### How much do solar cells cost to make, in terms of energy? How > ### much is just in terms of raw materials? What's their useful > ### lifetime? in the early 90's, solar cells took more energy to make than they'd ever return over their lifetime. are they much better now? > We may be able to run an electrical cable up > the space elevator, but cables tend to be heavy. if one has a space elevator, it may be possible to make a very simple uranium enrichment device (see dope exponentialz, supra) > A relatively small number of heavily guarded facilities extract, > refine, and transport most of the world's oil supply, which comprises > a substantial fraction of the world's energy usage. Rockefeller made his corner by betting that oil would not be found in substantial amounts anywhere beyond the northwest Pennsylvania region. By the time it was, he'd already set up Standard Oil, which as S.O., and Esso, is still with us today, in the news as Exxon Mobil. -Dave
