"An economist is an expert who will know tomorrow why the things he predicted yesterday didn't happen today." "Nimblefinger" at xkcd forums

Saturday, April 12, 2014

How the navy will turn seawater into fuel - SmartPlanet

How the navy will turn seawater into fuel - SmartPlanet:

'via Blog this'

Most interesting. I will need to speak to my more expert friends to understand what effect fuel made from CO2 from seawater, burned, and exhausted to the atmosphere might have on the ocean-atmosphere system.

ETA ("edited to add"): Lest no one misconstrue, this is NOT any sort of magic. The process requires significant energy input, that is, the EROEI ("energy return on energy invested") is less than one. In that sense, it's similar to hydrogen as a fuel. Yes, hydrogen can be burned or combined with oxygen in a fuel cell to provide motive power, but the energy required to get the hydrogen from natural gas or water exceeds that available from the internal combustion engine or fuel cell. But this technology would enable renewable energy sources such as solar, wind, OTEC (ocean thermal energy conversion) etc. to produce fuel that could be used for transportation, stored for burning in gas turbines for peaking power, etc. Also, see this article from the U.S. Navy Research Laboratory. Particularly take note of some of the skeptical comments.

Drag and weight as parameters of fuel economy in passenger cars

Image credit: www.modified.com
I've published previously that, for my car of that time that, below about 50 m.p.h., rolling resistance is the greater contributor to my need to burn fuel and above, it's aerodynamic drag. That vehicle was a Land Rover LR3 HSE, a much larger, heavier, draggier vehicle than my current chariot (a Lexus CT200h). Going through the same calculations, I find the crossover point to be about 38 m.p.h. That is (at steady speeds), below 38 m.p.h, rolling resistance provides the greater force to be overcome by burning fuel (or running electrons from high potential to low), above 38 m.p.h., it's aerodynamic drag. Below is a graphic taking these fractions from 0 to 40 m/s (about 89 m.p.h., far above my maximum). It should be noted that, in all of this, I only consider the external forces being overcome.

At my highway speed of 55 m.p.h., about 68% of my fuel is burned to overcome aerodynamic drag. And, since something like 70% of the miles I drive are on the freeway at my typical freeway speed, it's clear that drag represents a large portion of my fuel expenditures.

So let's take a look at how fuel economy in miles per gallon varies with the coefficient of aerodynamic drag (Cd). Below is a graphic showing an estimate of fuel economy as a function of Cd at 60 m.p.h. for a Toyota Camry-like vehicle (note that axes are not zero scaled). While the curve in this range looks to be close to linear, over larger ranges it's not, since fuel economy is inversely proportional to Cd and thus the graph is that of a hyperbola.

So what can be accomplished by reducing Cd from, say, 0.32 to 0.29? At 60 m.p.h. (and using my very simple model), this would result (for the Camry-like vehicle) in an increase from about 47.5 m.p.g. to 50.7 m.p.g. In a typical 12,000 mile year with 50% of the miles driven at highway speed, this would save some 8 gallons of fuel that might cost $32. Meh.


I attended a conference sponsored by the American Physical Society entitled "Physics of Sustainable Energy" (this was the third triennial such conference, I attended the second as well) at UC Berkeley. Amory Lovins of the Rocky Mountain Institute was the banquet speaker and made a presentation during the course sequence as well. Mr. (though Lovins has several honorary doctorates, I'm not sure that the "Dr." honorific is appropriate) Lovins has a huge portfolio of concepts that he claims, if implemented, would result in massive reductions in energy use in buildings (industrial, commercial, institutional, residential), transportation, and manufacturing. As time allows, I'll look into some of these.


But with respect to the topic of this post, Mr. Lovins stated that "two thirds of the energy used in a personal car is mass dependent." It seemed high when I heard it, let's consider. Energy is used in a car to accelerate (very much mass dependent but, in a hybrid, some of the kinetic energy imparted by accelerating a car's mass can be recovered by regenerative braking during deceleration), climb hills (very much mass dependent but descending hills can recover some, and in the case of hybrids with regenerative braking, much of the energy used in climbing), overcoming rolling resistance (mass dependent), overcoming aerodynamic drag (not mass dependent), and overcoming drive line friction and inertia moments of the rotating masses (both indirectly mass dependent in that lighter cars will need smaller, less powerful engines and, hence, lighter drive line components).


So, a lot of the energy is mass dependent. Is two-thirds a reasonable estimation? This is a complex question and will vary by car and by driver, but surely we can approach it. I'll assume that the car is not a hybrid. In addition to the usual coefficient of rolling resistance (Crr) assumptions, a number of others are required, among them: fraction of city vs. highway miles (I assumed 0.4 and 0.6); stops and starts per mile for both city and highway (I assumed 4 highway accelerations per 25 miles and 4 per mile in the city), engine efficiency (I assumed 22%). I ignored hill climbing (this would sway the fraction we're seeking higher). Should my readership clamor for it, I can elaborate on the process I used to calculate. In the end though, my estimate of the fraction of energy used in mass dependent aspects of fuel economy in this personal vehicle is 37%.

It's actually more complex than this since, at very low speeds, a large proportion of the energy used is devoted to keeping the engine going. In the extreme, stopped at a light, all of it is (though in my hybrid, the engine shuts off at a stop and I used to turn off the engine in my LR3 to eliminate this). And the amount of energy devoted to keeping the engine turning is dependent on the size of the engine and, thus, on the mass of the car. This argues for increasing the estimate of the mass dependent portion of energy used. But for the car I'm considering, it's hard for me to imagine that that portion exceeds half.

It's clear though that changes in the assumptions will have a large effect on this calculation. For example, reducing the highway portion would increase mass dependent energy; decreasing the average stop/accelerate cycles per mile in city driving would decrease it. In any event, it's clear that mass reduction in a vehicle will significantly enhance fuel economy. This post is already pretty long, so I'll elaborate in a future post.

Sunday, April 06, 2014

Elio Motors proposes an 84 m.p.g. "car"

The Elio Motors three wheeler is a design by Paul Elio that is expected to achieve a highway fuel economy of 84 m.p.g. (and a city fuel economy of 49 m.p.g.). The vehicle is expected to be on sale in 2015 at a price of $6,800. The price includes air conditioning, power windows, power door lock, AM/FM stereo, "and more." It's expected to have a 5 Star Crash Test Rating (the Elio has a reinforced roll cage, antilock brake system, stability control, airbags, and is made from carbon fiber composite).

It's not actually a "car" in the sense that we commonly think of them, it's a three wheeled vehicle. It seats two in a tandem configuration. For most states, that means that the Elio is regulated as a motorcycle (and in some states, a helmet will be required as things stand now). Pre-orders for the vehicle (with deposit) are said to be at 12,000, and Paul Elio believes that he can sell 250,000 Elios per year.

I can think of several applications where such a vehicle could excel. For example, I drive to work alone nearly every day and, in fact, well over 90% of the miles I drive my Lexus CT 200h are solo. I ran a quick check and the Elio would reduce my 400 gallons per year to 322 gallons for a savings of something like $312. Were I buying a new car, such a choice might be attractive at the $6,800 price point.

The Elio would likely also be a good candidate for a second vehicle for grocery shopping and other errands in a soccer mom family with the requisite minivan or SUV.

What about taxis? Here it's not so clear. The only door is to the driver's left and the rear seat is, charitably speaking, not optimized for the passenger experience (not to say claustrophobia inducing). And much taxi driving is in cities, where the Elio doesn't do any better than a Prius hybrid (and lots of my taxi rides recently have been in Priuses).

Fleet vehicles? Possibly, it certainly depends on the fleet and its intended use. What about for rental agencies? Here I'm also not so sure. I don't put a lot of miles on my rental cars when I'm out of town, I'm not so sure that I'm atypical. Thus, the fuel economy might not be particularly attractive. On the other hand, if the rental agency were to reduce the rental charge in proportion to the acquisition price of the Elio, we might have a deal.

Elio has a variety of fascinating financing options, the best article on those that I've seen is at this article in "the truth about cars" web site. The basis is that you get a credit card whose balance is the remainder of what you owe on the car after your deposit/trade in credit. You make payments on the card and when you purchase gas, you're billed for three times the gasoline cost. The difference between that price and the actual cost is used to pay down the car loan balance. The theory is that you're getting three times the fuel economy so you get the new Elio without paying anything beyond what you're used to paying for fuel for your (presumably) old, inefficient vehicle.

Now, one could say that the Volt, the Leaf, etc. do better than the Elio with respect to fuel cost (be they gallons or kilowatt hours) and one would be right. And those are four seat, four wheel vehicles. But, for the price of a Volt or a Leaf, one could buy an Elio and have some $30K left over. And it would certainly seem to be strong competition for the two seat Smart Car.

What about the mileage claim? The vehicle weighs about 1,000 pounds and sports a 70 horsepower, three cylinder engine. It doesn't look to be an aerodynamically smooth vehicle, but aerodynamics can be extremely deceiving. I can find no figures on drag coefficient or frontal area. But such trifles haven't stopped me before, so I'm going to plug and chug to see what results.

I'll assume a weight with driver of 1,170 pounds, a Cd of 0.32 (purely a guess, and one that I think favors the vehicle), tire rolling resistance coefficient of 0.0085 (assuming that Elio will go with low rolling resistance tires), an efficiency for the internal combustion engine of 30%, a frontal area of 2.3 m2 and a highway speed of 60 m.p.h. Running this in my little Mathematica model of vehicle fuel economy yields an estimate of 67 m.p.g., 17 m.p.g. below Elio's claim. I think I've been generous with respect to engine efficiency, so the likely areas where I've "cheated" the Elio would be drag coefficient and frontal area. Frankly, I think I've been pretty generous here as well, so I'll be very surprised if the typical driver* achieves 84 m.p.g.

Finally, I have to apologize for the lack of posts in the last nearly three months. As my karate instructor made us say when he asked us why we made some mistake in form or execution, "NO EXCUSE SIR!"

*Driving at 55 m.p.h. as I do yields an estimate of 78 m.p.g.


Saturday, January 18, 2014

Your share of the world | Grist

Your share of the world | Grist:

'via Blog this'

A fascinating perspective on available resources and what I've referred to as "self-poisoning." While the credit at the site is given to "Grist Staff," it was actually written by my college friend Dr. Michael Tobis, who now edits the Planet3.0 web site.

Saturday, January 11, 2014

MPGe?

The Nissan Leaf is rated by the EPA to achieve a so-called "MPGe" (miles per gallon gasoline equivalent) of 129 city, 102 highway, and 115 combined (note that the EPA sticker to the left is for an earlier year of the Leaf, I couldn't find a 2014 version). What is this "MPGe" of which they speak? While the linked Wikipedia article gives a thorough explanation, I want to briefly cover a couple of aspects.

First, the EPA makes the assumption that a gallon of gasoline is equivalent to 33.7 kWh (kilowatt hours) of electrical energy. In a straight comparison of chemical potential energy to electrical potential energy, this is accurate to within the variability of the myriad blends of gasoline available. The energy content of various fuels is listed here (though not in units I prefer).

I pay $0.16/kWh, so the 33.7 kWh would cost me $5.39, whereas a gallon of gasoline (I bought 8.6 of them yesterday) would cost me $3.639. On the other hand, that gallon will take me a trifle more than 50 miles whereas the 33.7 kWh will (by the EPA's reckoning) take a Nissan Leaf 115 miles. And my driving habits enable me to better the EPA rating of 42 m.p.g. for my car by about 21% so I might be able to drive the leaf 140 miles. Thus, I spend about 7.1 cents per mile for energy in my CT200h versus the 3.8 cents/mile I might spend in a Leaf.

What gives? The fact is that the battery to electric motor to driving wheels efficiency of the power train in the Leaf is going to be close to 90%, while the fuel to heat to mechanical motion to wheels in the internal combustion engine will be well under 30% on a good day. Over 70% is exhausted to the environment as waste heat.

It must be kept in mind that, neither in the EPA sticker ratings nor in my calculations for my car, is the energy used in getting the battery or tank filled included. That is, the energy to generate and transmit the electricity and the energy to extract crude, refine it to gasoline, and deliver it to the gas station is not included. It counts only what's in the vehicle. Supposedly, the CAFE ratings DO utilize the so-called "well-to-wheel" efficiency. There's a very nice comparison (albeit written by Tesla employees but still very credible) of the well-to-wheel efficiencies of a few examples of internal combustion engine vehicles, hybrids (non-plug in) and the Tesla battery electric vehicle here. The Tesla is about twice as efficient as a Prius on that basis. And DAMN those Tesla Model S roadsters look good!



Sunday, January 05, 2014

Convert my CT200h to plug-in?

My Lexus CT200h is EPA rated to get 42 miles per gallon combined. In it, over the 2 1/2 years I've had it, my total net has been 51.0 miles per gallon. The CT200h has a hybrid power train with a 1.4 kWh (kilowatt hour) NiMH (nickel metal hydride) battery. This battery is good for a mile or so at very low speed in so-called "EV mode." Plug-in hybrid electric vehicles (PHEVs) will have much larger batteries, enabling them to travel further and faster in EV mode. For example, the Prius PHEV is estimated to be able to travel 11 miles and at a maximum EV mode speed of 62 m.p.h. It achieves this with a 4.4 kWh battery pack. And the Chevy Volt now sports a 16.5 kWh battery pack that is estimated to provide an EV mode range of 38 miles.

I wondered if it would be possible to install a larger battery back and charging capability to my CT200h to convert it into a PHEV. As it happens, the answer is yes. And a huge variety of installations are possible, all the way from 2 kWh to 15 kWh capacity. Note that the Nissan Leaf, a pure electric vehicle (EV), sports a 24 kWh battery pack and a claimed range of 75 miles.

Should I install any conversion and, if so, which one? This can be looked at from an economic viewpoint and from a CO2 emission viewpoint. I'll look at both. As a baseline, my most common drive is the daily commute from my home in Anaheim Hills to my office in Long Beach. This round trip is about 62.5 miles and I do it, on average, four times each week. I'd be able to charge the vehicle at work, though I'd have to park at our laboratory facility about two blocks from our corporate offices. Such a strategy would enable me to utilize a battery pack with a 35 mile range to, on a typical day, never have to use the internal combustion engine.

What would this look like? The 7 kWh pack theoretically provides this 35 mile range, and I'd assume it would do so by discharging no more than 90%, but let's be conservative and assume that I'd need 14 kWh of charging per day. Assuming the charge system is 85% efficient, I'd draw about 16.5 kWh from the grid. At $0.16/kWh, this would cost about $2.64. I'll round down to $2.50 because I don't really quite go 70 miles on my daily commute.

Currently, with my 51 m.p.g. average, I use about 1.22 gallons of fuel in my commute. At a current price of $3.699/gallon, this costs about $4.50 per day. Thus, the conversion would save me something like $1.86 per day and, for 200 trips per year, I'd save $372/year. It's not completely clear from Plug In Supply's pricing page but it looks like I'd pay $9,875 for the 7 kWh system fully installed. Clearly, from a purely financial point of view, this makes no sense.

As to CO2 emissions, this is a bit more problematic to compute. I'd be getting half of my electrical energy from our house, where the City of Anaheim provides our electricity, and the other half in Long Beach, where Southern California Edison is the provider. And, assuming that some combination of coal, nuclear, and natural gas provides almost all of the electricity, I won't figure in emissions resulting from extraction and transportation of these fuels. This is reasonable, I'm not figuring the emissions resulting from extracting, refining, and transporting the gasoline I burn.

The calculation for the CO2 emissions from burning 1.22 gallons of fuel can't be exact as I don't know how much ethanol is in the fuel, and the mix of the various hydrocarbon chain lengths. I'm going to assume that the gasoline consists of n-heptane, C7H16 at that its density is 6 pounds per gallon. The chemical reaction would be C7H16 + 11O2 → 7CO2 + 8H2O. A mole of heptane has a mass of 100.2 grams. This mole results in 7 moles of carbon dioxide, each with a mass of 44 grams for a total of 308 grams.

Now, I'll be a bit general and figure that I use 1/51=0.0196 gallons of gasoline per mile. This gasoline weighs 0.118 pounds or 53.4 grams. This produces (308/100.2)*53.4 or 164 grams of CO2 per mile (this is the typical metric for vehicular carbon dioxide emissions) for a total on my commute of 62.5*164=10,250 grams or 10.25 kg of CO2.

That was the easy part. The electrical emissions are much more problematic because I've not been able to determine the mix of sources for Long Beach electricity. I'll just speculate. In any case, I need to determine the emissions related to 7 kWh from the City of Anaheim and 7 kWh from Southern California Edison in Long Beach.

I'm not able to find the appropriate mix of generating facilities to use to calculate for Long Beach, so I'll back into it from information from California State University Long Beach on this page, where it's stated that the renewable generation of 656,000 kWh avoided the emission of 471 metric tons of carbon dioxide. CSULB is only a couple of miles from our office, so this will have to suffice. So the generation of 7 kWh would involve the emission of 8.25*(471,000,000/656000) or 5,923 grams of CO2.

From Anaheim, I'll use the figures from my previous post on the Nissan Leaf. Using those numbers (and sparing my readers the gory details) I can figure that those 8.25 kWh involve the emission of 9,051 grams of CO2. The total emissions are thus 9,051+5,923 or 14,974 grams of carbon dioxide. Call it 15 kg. This is half again as much as my CT200h emits burning gasoline and the main culprit, as was the case for the Nissan Leaf I looked at, is that the City of Anaheim derives a surprising amount of its electricity from the burning of coal. And this information comes straight off of our bi-monthly bill!

So, when all is said and done, it makes no economic sense, and certainly no sense with respect to CO2 emissions, to undertake such a conversion. That's comforting because I don't have a spare $10K to throw at such a project!

And all of this probably overestimates the gains. The careful reader may have noticed that the Chevy Volt uses a 16.5 kWh pack to go 38 miles or 0.43 kWh/mile. The Nissan Leaf uses a 24 kWh pack to go 75 miles, or 0.32 kWh/mile. The Plug-In Supply site, where I got these figures, claims 35 miles on 7.33 kWh or 0.29 kWh/mile. It's true that these figures represent a Prius rather than a CT200h but I'm skeptical that the Prius is that much more efficient in terms of aerodynamics and rolling resistance than a Chevy Volt or a Nissan Leaf.

Friday, November 29, 2013

Ack! ANOTHER "capture the energy of walking/driving" system

I really don't want to turn this blog into a debunking site but some things just must be said. Here I described a completely impractical system for "capturing energy from pedestrians." And now we find an article from Science Daily about Mexican entrepreneur Héctor Ricardo Macías Hernández, pictured at left, who's developed yet another system for capturing energy from passing traffic - vehicular or pedestrian.

It apparently consists of a traffic wearing surface that sits five centimeters above street or sidewalk level. Passing traffic squeezes a bellows, compressing air into a tank (the linked article says "...where it is compressed..." but I don't imagine that that's accurate) from which it is expanded into a turbine to generate electricity.

Think about it. Your engine (either that of your vehicle or of your metabolism) is squeezing air into a tank. This work will reduce your gas mileage (or use your food energy) as your vehicle or your feet do the work of compression. There is no free lunch here. I'm surprised to see it in Science Daily which, although it is sometimes prone to exaggeration, usually doesn't publish nonsense.

There are no figures given, either in the Science Daily article or the articles linked from there, so I don't know what kind of traffic would be claimed to generate what kind of power. But I do know that, whatever the amount generated, it would be more efficient to burn natural gas in a turbine. Both vehicular internal combustion engines and human metabolisms are inefficient and compressing air is a lossy process. I'd love to see figures for this but it's yet another candidate for my prospective Greenwashing Hall of Fame. Yes, I know that the term "greenwashing" is typically applied to deceptive ad campaigns but I think it's equally applicable to deceptive products.

Update: In thinking about it, I suppose that one could concoct a scenario wherein a developing country with few energy resources would rather have the "rich" who own cars spend some of their energy (i.e., gasoline or diesel) purchase on providing energy for township than purchase natural gas, oil, or coal and then charge the poor residents for the electricity or pay for the fuel with taxes. But even there, better a gasoline tax with the proceeds used to pay for more efficient energy generation.

Solar panels on a truck?

I took my family to the LA Auto Show yesterday. Despite studies and articles contending that young people today are not so attached to automobiles, my son is absolutely captivated by them. He knows the makes and models, what he'd like, how he'd modify it, etc. I knew he'd have a great time and he did. I wanted to see developments in electric vehicles, plug-in hybrids (PHEV), etc., both production and concept.

I noted a pickup truck with a tonneau cover consisting of a solar panel and wondered about its practicality. Neither the Via Vtrux pickup (a series PHEV) nor the SolTrux panel option are in production, which is anticipated for 2014. It's a nice looking truck.

But is the solar panel practical? I have a Jeep pickup into which I've installed a 32 gallon water tank and other items designed to let me be self-sustaining in the Mojave, Sonoran, and Great Basin deserts of the Southwest. Where better to capture the sun?

So what are the appropriate numbers? We'd like to have battery capacity, dimensions and efficiency of the solar panels, and the claimed output. Here we find that the battery pack is 22 kWh. The dimensions of the panel array aren't given. but the standard bed is 78.7" long. The width isn't given but might be 65". The larger panel is stated to be 800 watts.

I see here that, in March (about average) I can expect on the order of 5 kWh/(m^-2*day) (kilowatt hours per square meter per day) for a panel mounted horizontally as it would be on a tonneau cover or roof rack. If I assume that the panels are 72" X 60", or 2.8 m^2 they should intercept 2.8*5 14 kWh per day. At 20% efficiency, I should get (surprise) 2.8 kWh/day. Assuming that I'd never let the battery pack below 20% charge, it would take 17.6/2.8 or a bit over 6 days to fully charge the battery. And the 22 kWh is represented to be good for 35 miles (though my desert miles are VERY hard on energy use). At that ratio, a day's worth of sunshine would take me (2.8/17.6)*35 or about 6 miles and probably a lot less in the rugged terrain where I'd be operating.

I suppose that, were I (through incredible stupidity or possibly a punctured fuel tank) out of gas and stranded, I could drive six miles per day for however many days it took to get to civilization (a very long way from the places I go). The fact of the matter is that it simply takes a lot of square meters to provide significant power. Verdict? NOT worth the estimated $3,000 price for the panels.

Update: Here's a clickable link to the article cited in the comments by Anonymous.

Saturday, November 23, 2013

Embarrassed to be conservative - a (sadly) continuing series

And yet, within MY definition and one that I will defend, I still am.

This Does Not in Any Way Imply That All Climate Deniers Are Obnoxious Blowhards | Climate Denial Crock of the Week:

'via Blog this'

A digression - should interest in sci fi be a qualifier for gifted programs?

Since my blog muse has, hopefully temporarily, abandoned me and my calculations regarding the energetic plausibility of carbon dioxide sequestration via carbonate minerals is taking much more time and effort than I'd anticipated, I'm going to go completely outside any subject space I've dealt with.

As a youngster, I read a LOT of Isaac Asimov's writing. While Asimov is very well known for his science fiction, I read none of it. What I read were his essays, which covered such an amazing breadth of topics that it's hard to believe that a single individual could do it. However, one that I read rankled.

Asimov was clearly a prodigy and, back in my youth, some regarded me as such. All that ever interested me was science and math and I was fortunate enough to attend a progressive (in the academic rather than the political sense) school. I was accelerated, I was offered training in scientific investigation, and I was offered the opportunity to choose what I studied, at least to an extent (I managed to squander most of this advantage upon reaching college but that's a story for another time).

But Asimov wrote an essay (I can't find it but remember it distinctly) suggesting that school children be assessed for accelerated learning or "gifted" (a label sometimes applied to me) programs based on their level of interest in science fiction. I found it then and find it now to have been pretty self-serving and self-aggrandizing for such an otherwise objective thinker.

I started both Asimov's "I, Robot" and his "Foundation" series and finished none of the stories, finding them much less interesting than reading and studying science and mathematics. I could likely count the science fiction stories I've read on the fingers of a hand (and I wouldn't need the thumb). I read "The Hobbit" and found it quite boring, and made it through two and a half of the "Lord of the Rings" trilogy (at Northwestern University in the early '70s, at least in my circles, it was a scarlet letter offense not to have read these - I had a fraternity friend who prided himself on reading the entire trilogy every year). Halfway through the third novel, I concluded that "this sucks, I'm reading it only because I'm supposed to" and put it down, never to complete it. Yes, I realize that Tolkien's works are fantasy rather than science fiction but I'm sticking with the point.

What point is that? It's not really clear, but it's a rant I've kept inside for decades. The trailers for "The Hobbit - The Desolation of Smaug" are popping up and brought it to mind. I've not seen any of the previous Tolkien adaptations (for the matter of that, I saw the original "Star Wars" in 1977 and have seen none of the prequels or sequels). I did watch all of "Star Trek" and some "Star Trek TNG" so I guess I'm not completely immune, but these shows could almost as well have been done as westerns!

In any case, I'm not at all sure that Asimov's razor (as I'll call it) would be the appropriate metric for determining the suitability of elementary school students for gifted programs (assuming such programs still exist in this day of No Child Left Behind-based teaching to the test). I'm sure it's a reflection of both my ego and my ability to hold a grudge that an essay I read, probably, over 40 years ago still causes resentment but perhaps this post will allow me to finally let it go!