reply to post by mc_squared
This is why I mentioned not to waste time with any calculations - because you're right, it only "seems" significant. We do release a lot of
energy, but it is still absolute bupkis compared to what we get every second from the Sun.
For example - the intercepted solar radiation flux (1370W/m2 x pi x Earth's radius squared) is about 11000 times the 2008 primary global power demand
of 15 TW.
And this brings us to the real problem with the calculations on which Global Warming is based. Referring back to
this link you provided earlier, the problem is that the Earth is not showing as much
blackbody radiation as would be expected if the temperature were stable. I liked this link because it gave me another starting point from which to
calculate.
We know that our measurements of this blackbody radiation correspond to a temperature of 255K. we also know that current surface temperatures,
averaged globally, are closer to 288K. Thus, reasons you, since more energy is coming in than going out, the planet must be warming. My contention up
until this point has been that this equation is incomplete, and that there are other sinks to help account for this energy differential.
Photosynthesis has been the major focus of that discussion.
But one could actually calculate an approximation of the amount of energy differential based on the information given, and I have (of course) done
so:
Total incoming energy = 239.23 W/m²
T = (I/σ)^-4 = (239.23/5.67·10^-8)^-4
= 255K
Our observed surface temperature is 288K, so we rewrite the equation as:
I = σ · T^4 = 5.67·10^-8 · 288^4 = 390.08 W/m²
390.08 W/m² - 293.23 W/m² = 96.8 W/m²
We are apparently gaining energy at the rate of 96.8 W/m².
The surface area of the planet is approximately 5.176·10^21 m².
based on an average radius
5.176·10^21 m² · 96.8 W/m² = 5.01·10^23 W or 5.01·10^23 J/s[/align]
My first impressions at seeing this result are:
- it definitely dwarfs mankind's energy budget, as you say above, and
- Would this extreme amount of energy being trapped not be enough to cause marked changes, far greater than what we are seeing now?
Now I have to call you to task on something that this emphasizes:
Originally posted by mc_squared
Now look at it like so: The Earth has been slowly absorbing and storing this energy for a very long time. In doing so, I guess you could say it has
"naturally" reduced the required energy out/equilibrium temperature in the process...
But now in the last 150 years - we've gone and dug it all up and released it virtually all at once. Suddenly the equation is actually more
like:
Energy In - Energy reflected + Energy converted = Energy Out
Furthermore - removing that variable from the equation over hundreds of millions of years had a negligible effect on climate change. But how do you
feel now about suddenly reintroducing it all in a geological eyeblink?
Originally posted by mc_squared
This is why I mentioned not to waste time with any calculations - because you're right, it only "seems" significant. We do release a lot of energy,
but it is still absolute bupkis compared to what we get every second from the Sun.
Two seemingly conflicting statements. When fossil fuels are consumed, all of the chemical energy is released. At our present stage of technological
development, this conversion is terribly inefficient, meaning that the vast majority of the chemical energy inherent in oil is released as
heat. So either the oil consumption is producing enough heat to be significant, or it isn't. You can't (honestly) argue both sides.
In truth, I just showed that it is indeed insignificant as it compares to the energy differential that is the basis for Global Warming.
If we found a way to cover less than 1% of the world’s desert area (~80,000 km2) with 10% efficient modules, that would be all that was
needed to generate the world's total electricity consumption in 2008 (17000 TWh).
17,000 TWh yearly is approximately 1.94 TW. Dividing that by the energy produced at 10% efficiency (136 W/m²) gives us 14,300,000,000 m² or 14,300
km². The
Sahara Desert itself covers 9,000,000 km². In short, you are correct in your calculations;
there is plenty of desert available to place enough solar cells. But those same calculations ignore many of the boring details.
Firstly, there is the equipment cost. We are talking about a global project that involves covering 14,300 km² with solar cells, which are pretty
expensive to manufacture at this time. One of my
surplus suppliers,
All Electronics, has panels that cost upwards of $1000
per square meter at the efficiency rate you mention. $1000/m² is $1
billion per square kilometer, and
$14.3 trillion to cover the
14,300 km² calculated to be needed.
Secondly, 14,300 km² is not sufficient. At best, an area will get a 50% solar duty cycle, so that figure has to be doubled to 28,600 km²... still
enough room on the planet physically, but the price tag for the solar cells alone has jumped to $28.6 trillion. We are now well above the GDP of the
planet.
Just in case you are about to complain about how all this is moot because the companies should be forced to make them cheaper, let me remind you of an
economic reality: a huge chunk of the cost of these solar cells is for labor. That means people would have to go hungry (as in working for nothing,
otherwise called slavery) to fulfill this goal. Another huge part, perhaps larger than direct labor is the equipment needed to manufacture them,
equipment which must be manufactured
by more workers. So if you want to somehow force a cut in the cost of the solar cells, bear in mind you
are telling untold numbers of people trying to feed their families to 'suck it up', become slaves, and go hungry.
And I would not even be sure that this cost was really accurate. That price is surplus, which means that someone, somewhere either overbought or
discontinued a product and was left with a boatload of these cells. They sell them at pennies on the dollar to places like All Electronics, who then
resell them at cut-rate prices to individuals and companies. Surplus is great for building prototypes, or sometimes even for limited production runs,
but when we are talking about a project of this size, surplus supply is simply not an option. So the actual price may well be higher, and certainly
will not be lower.
Now we have to consider the problem of getting the power to where it is needed; there is not a lot of industry in the desert. So we have to consider
transmission requirements. Electrical loss is directly related to current, so to minimize losses high voltage (upwards of 13.8kV) is typically used to
transmit the same amount of power with less current and less losses. High voltages are notoriously difficult to handle safely and thus require that
the voltage be brought back down to moderately safe handling levels at the point of consumption (anywhere from 240V dual-phase to 440V three-phase in
the USA). To make this voltage transformation, transformers are needed. Transformers work only on AC power, not on DC. So the low-voltage DC power
supplied by the solar cells must be transformed into high-voltage AC before it can even be used effectively.
Then there is the duty cycle problem. Energy is needed 24 hours a day, yet in any one location the sun is available to power cells for 12 hours on
average at best. That means that half of the energy produced must be stored somewhere. So now we can add the cost of batteries to this equation. A
typical lead-acid battery (which is probably the lowest cost per watt and the hardiest among the rechargeable types) costs at least $50 wholesale. It
produces 12V nominal at a little under 100 Amp-hour (Ah). That is 1200 Wh of power storage, or 100 W over a 12-hour period. We need one-half of the
rated daily output of our solar bank, or 12 hours capacity. That capacity per hour has already been calculated to be 1.94 TW, meaning we need enough
batteries to store 1.94 · 12 = 23.28 TW of power. dividing this by the rated power storage of our batteries gives us 23,280,000,000,000 W / 100
W/battery = 238,000,000,000 or 238
billion batteries.
Can you even imagine the work force required to maintain this colossal bank of batteries? How many workers alone would be needed to change out
batteries as they died, 24 hours a day, 365 days a year?
This is called 'initial assessment'. Any new idea must go through this initial assessment to ensure practicality. I could theoretically harness the
power of lightning to power a city as well, but the requirements of such a device make it tremendously impractical to do so.
At this time, solar cells, due to their energy output, physical size, and cost, combined with the solar duty cycle, are simply not practical for
large-scale production of electricity. They are wonderful for small scale applications, and even better for isolated areas with small-scale energy
requirements. It is even slightly practical to power a high-efficiency home from them in some cases. But industry? A city? A nation? A
world?
Sorry, no. Not practical. Not every technology is scalable.
I mean even if you don't think CO2 is bad, you realize coal and oil lead to a whole plethora of other environmental problems right? (If you
don't believe me then I suggest taking a dip through the Gulf of Mexico right now).
I doubt you can search through ATS and find one single post I have ever made that states that fossil fuel consumption is a good thing for either the
environment or for the economy. What I have said is that at present fossil fuels are the
only viable energy source we have at our disposal.
There is a huge difference between the two positions.
Present me with a scalable, efficient, carbon-free energy source and I will quit worrying about Cap & Trade and its implications as compared to the
case for CO2-based Global Warming. There will be no need to worry about it then, because oil will quickly disappear from the political scene. Until
then, in light of the seriousness of the political actions now being proposed under the guise of Global Warming, I have to question the science.
Because it would be a true disaster to turn the entire gamut of potential energy reserves in the world over to a handful of governments, depriving
people of their ability to partake of all society has to offer, especially when there was no actual emergency to begin with.
In other words, leave the politics out of it until the science is well understood, and you will not encounter the fiery rhetoric and in-depth
examination of every aspect. Extraordinary proposals, as extraordinary claims, require extraordinary proof.
But you're going to have to elaborate a bit more on what exactly you believe is going on - because I'm not entirely clear on what you mean
about spectroscopy picking up "chemical conversions" for example.
Certainly.
Spectroscopy is the study of light as it is emitted or absorbed by different molecules. For instance, if we see light coming from a star, we can
examine that light to determine how much of which element is present in the star. If an abundance of hydrogen exists, there will be certain
frequencies of light which are muted, corresponding to the frequencies which we know hydrogen to absorb.
This works well in stars, primarily since there are only a few differing elements which make up the majority of star matter. Hydrogen, helium, and
carbon are among those.
But if we try to measure the light coming from Earth as blackbody radiation, then we are seeing absorption bands from several different compounds.
Nitrogen, water vapor, oxygen, ozone, and carbon dioxide are only a few of the more common compounds. In many cases, the spectroscopy bands of these
different compounds overlap, meaning that we see an indication of one of several compounds rather than only one.
Also, in a star there is sufficient energy to keep molecules and atoms in excited states, meaning that they are absorbing energy. Energy cannot be
absorbed if it does not exist, and even if it exists at low levels some might just make it out without being absorbed. Irrelevant if there is an
abundance of energy, but when the energy output is less than abundant, or when the concentrations are less than appreciable, the readings become
difficult to decipher.
What I am calling into question here is the way CO2 levels are measured. I am sure you can set me straight on how this is accomplished accurately.
But now - because some of the energy flow out is being "held up", there is only one solution available: the temperature must increase to push
it out at the same rate again and restore the equilibrium. It's like an electric circuit and Ohm's Law: I = V/R. If our resistance has increased,
then we must increase our voltage to maintain the same current. Hence the whole idea of "forcing".
Awwww, you used an electronic analogy... how kind of you!
Any energy received and not re-transmitted back into space would be absorbed by the planet. Any such energy absorbed as heat will raise the
temperature. As the temperature rises, the temperature difference increases and thus causes an increase in the energy flow, which results in more heat
being released. Is that about correct?
It can't be:
So what any GHG does is upset this balance. More than actually "trapping" heat - it is simply obstructing the flow, upping the resistance,
etc. But this is all about radiative equilibrium and has nothing to do with convection or conduction at this point.
Thermal conductivity is not radiative; it is conductive. The premise above, where an increase in temperature would cause more energy to be expended,
is based on conductive heat transfer.
Radiative heat transfer encompasses two phenomena that differ form conductive heat flow. One is that not only the intensity of the radiation, but the
frequencies of the emitted radiation change with temperature. This changes the dynamic since every compound has different absorption spectra. A large
enough difference in the proper atmosphere could lead to either a rapid self-correction or to a sudden increase in temperature as the radiation
emitted moves through the spectrum.
The other phenomena is that of saturation of the greenhouse gases, but I have spent two days trying to complete this reply, and things just keep
needing to be done. So for now I will end it here and await your response.
TheRedneck
- but I did tell you I'd never looked at the
issue that way, so it was a spur of the moment chance to meddle with the logic there as we went along. 
