The capacity difference between the two cells is not as large as the Amp-hour rating would seem to indicate. Li-ion cells operate at about 3.6 volts, while NiMH cells operate at about 1.2. Thus, assuming constant voltage during discharge and zero internal resistance (incorrect, but it makes this easier), you can calculate capacities of:
1.2V * 2.2Ah = 9.5kJ for the AA cell and 3.6V *.53Ah = 6.7kJ for the Li-Ion cell.
Given the higher energy density per mass of Li-Ion cells and the form factor flexibility ditching the AA provides, this seems like a good tradeoff.
"More C02 means more plants! Oh no!!!" This doesn't really help! Sure, you can produce a net carbon sink for a few years as global plant distribution/growth rates take advantage of the increase in C02 (the increase in temperature will help as well) but pretty quickly you reach a steady state again. Remember that more plants growing means more plants dieing and getting converted back to C02 as well... and at that point you have more carbon sequestered in the biosphere and a greater turnover, but no greater net sink than we have now.
"the natural processes that take place on the earth (volcanoes, most notably)". Volcanic C02 output is estimated to be over 100 times less than anthropogenic output. See my other posts for cite.
Re:The Earth's temperature has ALWAYS fluctuated.
on
Larsen Ice Shelf Collapses
·
· Score: 3, Informative
"Even relatively massive surface events like Krakatoa (which IIRC put out more dust and "greenhouse gasses" in one swell foop than all of humanities' efforts combined)".
This "volcanos are worse greenhouse emitters than humanity" bit keeps popping back up ever since Rush was spouting about it for a while in the early/mid 90's. In fact, total global volcanic C02 output is estimated to be about 1/150th that of athropogenic C02 output [Gerlach, T.M., 1991, Present-day CO2 emissions from volcanoes: Transactions of the American Geophysical Union (EOS), v. 72, p. 249, and 254-255.]
Sulfer is a slightly different story -- volcanos actually make up around 50% of natural sulfer emmisions! This is still only about 1/10 as much as human activity produces, however.
About the only area of concern in which volcanos outstrip human emissions are stratospheric injection of various aerosols and dusts during explosive erruptions (rare!) and emmissions of certain heavy metals like selenium. Not lead though -- we still win there:)
Going beyond that to your several orders of magnitude swamps... anthropogenic C02 emmissions total somewhere around 5 to 10Gigatons of carbon per year... gross terrestrial biosphere carbon release is somwhere around 60GT/year, which is in fact less than one order of magnitude. Couple that with the fact that gross terrestrial biosphere _uptake_ of carbon is quite close the emissions, and the net effect on the atmosphere from anthropogenic sources is greater.
Like them, yeah...:) But not just mirrors. Retroreflectors reflect light back on a course essentially parallel to the incoming rays. This makes them kind of creepy to look into, since no matter how you rotate them, there's an eye staring DIRECTLY back at you:)
To see this in person, walk up to a surveyor at a construction site sometime... if you're lucky and they're using an optical total station, there'll be someone walking round with a pole w/ a corner cube reflector (a type of retroreflector) on top. This is used so that the pulses of light coming out of the total station get reflected back to the station no matter how the pole guy has the pole oriented.
Another good example is the material highway signs and license plates are coated with -- they show up in your headlight beams so well because much more of the light reflecting from their surface heads back toward the light source (the headlights, very close to being in line with your eyes) rather than being scattered or reflected off into a less useful direction.
Check out http://www.leica-geosystems.com/ims/product/tps500 0_reflectors.htm for some pics...
Slashdot Mirror
The capacity difference between the two cells is not
.53Ah = 6.7kJ for the Li-Ion cell.
as large as the Amp-hour rating would seem to indicate.
Li-ion cells operate at about 3.6 volts, while NiMH cells
operate at about 1.2. Thus, assuming constant voltage
during discharge and zero internal resistance (incorrect,
but it makes this easier), you can calculate capacities of:
1.2V * 2.2Ah = 9.5kJ for the AA cell and
3.6V *
Given the higher energy density per mass of Li-Ion
cells and the form factor flexibility ditching the
AA provides, this seems like a good tradeoff.
"More C02 means more plants! Oh no!!!" This doesn't really help! Sure, you can produce a net carbon sink for a few years as global plant distribution/growth rates take advantage of the increase in C02 (the increase in temperature will help as well) but pretty quickly you reach a steady state again. Remember that more plants growing means more plants dieing and getting converted back to C02 as well... and at that point you have more carbon sequestered in the biosphere and a greater turnover, but no greater net sink than we have now.
"the natural processes that take place on the earth (volcanoes, most notably)". Volcanic C02 output is estimated to be over 100 times less than anthropogenic output. See my other posts for cite.
"Even relatively massive surface events like Krakatoa (which IIRC put out more dust and "greenhouse gasses" in one swell foop than all of humanities' efforts combined)".
:)
This "volcanos are worse greenhouse emitters than humanity" bit keeps popping back up ever since Rush was spouting about it for a while in the early/mid 90's. In fact, total global volcanic C02 output is estimated to be about 1/150th that of athropogenic C02 output [Gerlach, T.M., 1991, Present-day CO2 emissions from volcanoes: Transactions of the American Geophysical Union (EOS), v. 72, p. 249, and 254-255.]
Sulfer is a slightly different story -- volcanos actually make up around 50% of natural sulfer emmisions! This is still only about 1/10 as much as human activity produces, however.
About the only area of concern in which volcanos outstrip human emissions are stratospheric injection of various aerosols and dusts during explosive erruptions (rare!) and emmissions of certain heavy metals like selenium. Not lead though -- we still win there
Going beyond that to your several orders of magnitude swamps... anthropogenic C02 emmissions total somewhere around 5 to 10Gigatons of carbon per year... gross terrestrial biosphere carbon release is somwhere around 60GT/year, which is in fact less than one order of magnitude. Couple that with the fact that gross terrestrial biosphere _uptake_ of carbon is quite close the emissions, and the net effect on the atmosphere from anthropogenic sources is greater.
-Ethan O'Connor
Like them, yeah... :) But not just mirrors. Retroreflectors reflect light back on a course essentially parallel to the incoming rays. This makes them kind of creepy to look into, since no matter how you rotate them, there's an eye staring DIRECTLY back at you :)
0 0_reflectors.htm for some pics...
To see this in person, walk up to a surveyor at a construction site sometime... if you're lucky and they're using an optical total station, there'll be someone walking round with a pole w/ a corner cube reflector (a type of retroreflector) on top. This is used so that the pulses of light coming out of the total station get reflected back to the station no matter how the pole guy has the pole oriented.
Another good example is the material highway signs and license plates are coated with -- they show up in your headlight beams so well because much more of the light reflecting from their surface heads back toward the light source (the headlights, very close to being in line with your eyes) rather than being scattered or reflected off into a less useful direction.
Check out http://www.leica-geosystems.com/ims/product/tps50
Nope, the new_ia32_branch is not folded into
2.95. If you cvs co it its version number is
2.96 right now, but I don't know when the merge
will occur.