36 Replies to “E=MC2 vs E=MV2”

  1. Oh, only 70 trillion times more weight… I thought it was a BIG difference!
    So does this mean damming up the Qu’Appelle wouldn’t be enough to power Saskatchewan?

  3. A minor nit is that while E=MC2, E=.5MV2. Or
    E=MC**2
    E=.5*MV**2
    in most programming languages.

  4. I knew there was a significant differance but this lays it out plainly. Wind and solar are both lower yield energy sources, and also require some form of storage for non productive periods.I suspect there are many neo-luddites out there who figure a few square feet of solar panel or a couple of small wind turbines will take them to the promised land of “Offthegrid”.Much opposition to Nuclear and hydro power is based on this magical thinking.

  5. One of the things I have to keep pointing out to my scientifically illiterate friends is that it does not matter how much more “efficient” they make solar panels; not enough radiant energy per unit area hits the Earth’s surface for them to be useful at any efficiency, including 100%.

  8. The green energy people do not accept the validity of mathematics, to them it is a very subjective science. Take their word for it.

  10. Hydro electric dams fail and have killed many more people than nuclear accidents.
    One such dam burst in 1975 and killed 85,000 people in China but has not stopped the building of more hydro dams.

  13. At one pojnt in time, I admired Mr hawkings, over time though, he has changed.
    In pursit of “pure” intellect and physics, he “was” perhaps without equal.
    Unfortunately, he has digressed……to the point or irrelevance, excepting the fringe.
    Whatever mantra he esposes, is “not” without challenge. Beliefs are what they are, and shall endure long past Mr Hawkings residence here.
    Thoughts and feelings, bitterness, vitriole, etc, shall fall away with time, and his demise. We are all creatures of the present, opinions and writings shall dissappear, unless verified and validated.
    Unfortunate………but true.

  14. Let alone coal and nuclear:
    “Cameco restated British environmentalist Sir James Lovelock’s suggestion that people try to imagine they are a government minister required to decide what fuel to use for a new power station being built to supply half a large city:
    ‘Every year, there are the following environmental consequences: using coal requires a 1,000 kilometre line of railway cars filled with coal which will emit billions of cubic feet of greenhouse gases, creates dust and more than 500,000 tonnes of toxic ash; using oil needs four or five-super tanker loads of heavy oil imported from unstable parts of the world, emits nearly as much greenhouse gases as coal plus huge volumes of sulphur and other deadly compounds that turn into acid rain; importing natural gas over long distances by ships and pipelines prone to accidents and leaks, emissions are highly polluting and the gas supply is vulnerable; or about two truckloads of cheap and plentiful uranium with essentially no emissions.'”
    I can’t even imagine how many turbines would be required.

  15. All of those energy sources have their drawbacks. Wind obviously blows, but damns tend to kill a lot of people. Nuclear is every bit as unfeasible and subsidy-addicted as wind (http://www.cato.org/pub_display.php?pub_id=12947) and no, that is not a result of over regulation. The Cato institute did a study to debunk that myth.

  16. “not enough radiant energy per unit area hits the Earth’s surface for them to be useful at any efficiency, including 100%”
    This is, of course, sheer nonsense. With 100% efficiency, you’d get about 1kw per square meter. Accounting for night time and periods of lower illumination, you end up with 500w per square meter. At that efficiency, the average roof could easily provide enough electricity for 2 or 3 houses. Either you don’t know math, or you’re just lying.

  17. Alex, you only get 1 kW/sq.m. at the top of the atmosphere at the equator. On the surface, the energy is less than half because of atmospheric absorption. Given that the majority of the earth’s energy demands are outside the two tropic lines, you have to factor in the curvature of the earth, which roughly halves it again.
    When you get that energy at the earth’s surface you then discover that only 13% of photons have sufficient energy (measured in MeV) to release an election in a photoelectric cell. So, the maximum possible yield is 1 x 0.13 x 0.5 x 0.5 = 3.25% of energy emitted by the sun and impacting the top of our atmosphere.
    That is the maximum potential. You then have to allow for weather effects. Your halving of it is insufficient. Even under light overcast the loss of photons is about 80%. And of course you halve it again for diurnal variation.
    LAS: the Forbes and Van Doren article is riddled with so many errors of fact and judgment as to be utterly worthless. Suffice it to say that on the basis of actual performance and loss of life to date, including Fukushima, nuclear power is by far the safest way to generate electricity, bar none including the renewables.

  18. “Alex, you only get 1 kW/sq.m. at the top of the atmosphere at the equator. On the surface, the energy is less than half because of atmospheric absorption”
    ‘Outside Earth’s atmosphere, the sun’s energy contains about 1,300 watts per square meter. About one-third of this light is reflected back into space, and some is absorbed by the atmosphere (in part causing winds to blow).
    By the time it reaches Earth’s surface, the energy in sunlight has fallen to about 1,000 watts per square meter at noon on a cloudless day.’
    http://www.ucsusa.org/clean_energy/technology_and_impacts/energy_technologies/how-solar-energy-works.html
    Try again?

  19. The article I linked to lists 400 Watt square meter energy at the ground and with a efficiency of 25% you get about 100 Watt square meter from photoelectric cell.
    So cgh and I have a consensus and therefore we are correct, I reviewed his argument and agree with it 🙂

  20. Alex, the first sentence from ucsusa you quoted is correct. The second is garbage. If 1300 watts hit and 300 is reflected back into space then 1000 hitting the surface would mean NO atmospheric loss whatsoever. Whoever wrote this at UCS has not the slightest understanding of basic physics. Or neglected to proofread.
    Do try to read the rubbish you quote. Yeti is right; the surface energy potential is 400, reduced by a further half by curvature effects.

  21. To the magical thinkers on the left, mathematics and physics, like gender, are social constructs.

  22. Notwithstanding my earlier comment,
    Alex blathers:
    Outside Earth’s atmosphere, the sun’s energy contains about 1,300 watts per square meter. About one-third of this light is reflected back into space, and some is absorbed by the atmosphere (in part causing winds to blow).
    By the time it reaches Earth’s surface, the energy in sunlight has fallen to about 1,000 watts per square meter at noon on a cloudless day.‘     (my emphasis added)
    First, 1300 * 2/3 ~= 900 (that’s what’s left after the energy reflected back, according to your nameless source)
    Second, 900 – (some absorbed by atmosphere) is less than 900
    Third, your source cites the BEST case – noon on a cloudless day – and doesn’t cite that the sun must be directly overhead (i.e. somewhere between Cancer and Capricorn).
    So, if one accepts your source’s initial premise, the energy hitting the earth in the very best case has to be less than 900 w/m2 (which, to me, already throws your source in doubt, since they clearly couldn’t do the simple arithmetic above to arrive at their “1000 w/m2” figure), and that’s for only a few minutes a day. Throw in a cloud or two, adjust for latitude, and you get a much lower number.
    Nice try. Feel free to play again.

  24. I’m a big fan of appropriate solar power and, in my case, that consists of end of season sale solar powered LED lights which I have along my garden paths. These are really only useful during the shortest nights of the year when they have had the day to charge and it’s already starting to be light before they get dim. Admittedly these are cheaply made chicom NiCad batteries which generally just last a season or two and the solar cells look like rejects also.
    It’s enough work to clean the dirt off this tiny area of solar cells and I’d hate to think how much work a roof mounted installation would require. Playing around with an ammeter and a solar cell revealed marked positional effects on power production. Yes, having the solar cell pointed directly at the sun gave impressive power output but in a few minutes the cell was no longer directly pointed at the sun and power output dropped significantly. The light curves I recorded convinced me that outside of powering microwatt circuitry, solar power is useless. Plants do a pretty good job of collecting solar energy and storing it. After a few years we can chop down trees and burn them in the winter for heat.
    IMHO, the large scale use of current solar cells is doomed to failure. The only thing that I can see succeeding is genetically engineered crops such as a sugar cane/electric eel hybrid that would have a root system which conducted the generated electricity to ones home. Alternatively one could create a poplar/electric eel hybrid as poplars are a plant that share a common root system and it’s far easier to let a plant generate a vast solar collection area than to rely on chicom slave labor.

  25. One such dam burst in 1975 and killed 85,000 people in China but has not stopped the building of more hydro dams.
    ~scott
    Yeah, that was 3 Gorges Dam.
    Estimates at the time were 2 million Chinese killed.
    I think those estimates were conservative/low balled.
    (Chinese like to ‘save face’ by lying about these failures)
    The reason for the disaster was that 5/7 sluice gates were rusted shut and couldn’t be opened to allow a 100 year peak rainfall to pass through the dam.
    Because of the Chinese cultural penchant for zero maintenance, this kind of avoidable disaster will no doubt happen in China again.
    However, this is a bad argument for banning dam development and a really good argument for not allowing Chinese people to supervise/construct or otherwise take part in the maintenance of critical infrastructure in nations outside of China.

  26. “The release of energy from splitting a uranium atom turns out to be 2 million times greater than breaking the carbon-hydrogen bond in coal, oil or wood. Compared to all the forms of energy ever employed by humanity, nuclear power is off the scale. Wind has less than 1/10th the energy density of wood, wood half the density of coal and coal half the density of octane. Altogether they differ by a factor of about 50. Nuclear has 2 million times the energy density of gasoline. It is hard to fathom this in light of our previous experience. Yet our energy future largely depends on grasping the significance of this differential.
    One elementary source of comparison is to consider what it takes to refuel a coal plant as opposed to a nuclear reactor. A 1000-MW coal plant – our standard candle – is fed by a 110-car “unit train” arriving at the plant every 30 hours – 300 times a year. Each individual coal car weighs 100 tons and produces 20 minutes of electricity. We are currently straining the capacity of the railroad system moving all this coal around the country. (In China, it has completely broken down.)
    A nuclear reactor, on the other hand, refuels when a fleet of six tractor-trailers arrives at the plant with a load of fuel rods once every eighteen months. The fuel rods are only mildly radioactive and can be handled with gloves. They will sit in the reactor for five years. After those five years, about six ounces of matter will be completely transformed into energy. Yet because of the power of E = mc2, the metamorphosis of six ounces of matter will be enough to power the city of San Francisco for five years.”

  27. No, Oz, it wasn’t. It was the Banqiao Dam, built in 1951 about 30 years before Three Gorges even existed. It was an earth dam, typical of what was built in Third World nations, not a concrete arch dam of which Three Gorges is an example. It was one of a series of dam failures in China at that time because of a massive typhoon.
    “…and a really good argument for not allowing Chinese people to supervise/construct or otherwise take part in the maintenance of critical infrastructure in nations outside of China.”
    Meaningless, bigoted drivel. Are you pretending that China today, with its 250,000 engineering graduates annually, in any way compares to China of 50 years ago?

  28. Alextroll:
    “Either you don’t know math, or you’re just lying”.
    I really loved this part, Alex does his usual, accuses people here of being stupid, or lying…then gets his backside handed to him.
    Buhahahahahahahah, Alex the phony soldier strikes out again, bah-bye:)

  29. When you consider the fact that there are literally MILLIONS of dams, I think we could agree that dams are likely the safest of all human power technologies.

  30. No, cgh, the Banqiao Dam was completed in 1952.
    You are correct that I was confusing it with the 3 Gorges dam.
    Are you pretending that China today, with its 250,000 engineering graduates annually, in any way compares to China of 50 years ago?
    Fake Chinese degrees are another topic altogether.
    I wish I could should you all the photos I have of Chinese engineering disasters.
    The Banqiao Dam failed because of BAD MAINTENANCE.
    Rusted shut sluice gates.
    Are the Chinese still as bad at maintenance today as they were 50 years ago?
    Yes.
    It’s a cultural failing.
    Go ahead, call it bigoted meaningless drivel, it doesn’t make my ascertion any less true.

  31. Jon, actually they’re not the safest. The Paul Scherrer Institut has documented this over the past century. On a basis of loss of human life, hydraulic is nearly as dangerous as coal in 3rd world nations in terms of loss of life per unit of energy produced. To my knowledge, the only electric energy system accidents in Ontario over the past century causing deaths in the general population have been hydraulic related. There were several just in the past decade.
    Oz, please substantiate your claim that the Chinese are bad at maintenance and that this is a cultural failing, as opposed to the normal growing pains of any very rapidly expanding and modernizing economy.

  32. cgh, just drive through any district of your nearest city where the neighbourhood has a majority Chinese presence and see for yourself.
    Homes and garages in need of paint, lawns full of weeds in need of cutting/watering, garage doors hanging askew, it’s all there.
    You either haven’t had much contact with the Chinese or you are a poor observer.
    I could give you reems of photos of bad Chinese construction and engineering in China itself if the filter on this blog didn’t limit me to 2(sometimes only 1) links/comment.
    Last but not least, I don’t care what you think.
    “as opposed to the normal growing pains of any very rapidly expanding and modernizing economy.”
    Quality Fade
    http://tinyurl.com/nqsgur

  33. cgh, just drive through any district of your nearest city where the neighbourhood has a majority Chinese presence and see for yourself.
    Homes and garages in need of paint, lawns full of weeds in need of cutting/watering, garage doors hanging askew, it’s all there.
    Really? I live in Richmond Hill, Ontario, right by Markham, both of which have large Chinese communities. If you drive through Bayview Hill (between Leslie/Bayview and Major Mac/16th), which is a heavily Chinese area, you will see immaculately maintained houses, yards, cars, etc. Same thing in the new subdivisions north of Major Mac in the same area. Same thing all through Markham.
    This is the among the most ridiculous assertions I’ve ever heard at SDA.

  34. This is the among the most ridiculous assertions I’ve ever heard at SDA.
    ~KevinB(E-Bike Boy)
    Well, you should try reading instead of hearing then.
    Not only does it hold true in the Chinese areas in Calgary but in every Chinese area I’ve seen.
    Chinese people run things down and don’t do maintenance.
    Here is book for anyone who is into reading more than ignorant E-Bike Boy is:
    http://tinyurl.com/3tz4ums

  35. The issue is not about nationality or who maintains what (that is racist by the way) but about the appropriate application of solar panels for power generation. At the current level of sophistication and efficiency solar panels are only profitable where low power devices need power in areas where the infrastructure does not exist.
    The most common application of solar power is in SCADA applications providing remote monitoring and control of systems like batteries (control stations) in the oil field.
    I have been involved in the application (and instruction of the application) of these systems since the eighties. They do the job, but are expensive, requiring the solar panel, voltage regulator and batteries. Further more they must be sized to maintain power in the months of January and February.
    The further north the more reserve that must be built in. Also overcast conditions must be considered as well.
    They are not without maintenance, in the winter snow and ice build up can affect their output, but I guess you could use heaters to melt the snow and ice (LOL), and in the summer a build up of dust of bird crap can affect them.

  36. The headline could be improved by the use of the {sup} {/sup} tag to get the exponents desired. Those of you who live in the prairies forgot to mention tree pollen that can have an affect in the spring.

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