kevin@ttidca.UUCP (12/02/87)
I have been hearing nothing but doom and gloom about the
greenhouse effect that is currently causing long-term global
weather changes. It's also believed that the recently-discovered
melting of the Ross ice shelf in the Antartic ( ...quarter-million
square mile icebergs ?!) is a direct result of this phenomenon. I
would greatly appreciate any information or discussion about the
current research is being done on the following questions.
1. Are CO2 levels rising sufficiently to cause the ice caps to
melt fast enough to noticeably change the sea level in the
near (50 +-) years?
2. Are deforestation & industrialization the primary causes
for what's going on, or can the Earth's axis precession
have some involvement also?
3. Is there any political action going on to help get some
results in on *WHY* desertification is occurring in certain
parts of the world?
4. What is the predicted effect of defoliation of the Amazon
in terms of the global environment?
5. Is there a (...I think I know the answer to this one) chance
that things might get better?
Tanks in Advance
Kevin: !{csun,rdlvax,trwrb,psivax}!ttidca!kevin
---------------------- cut here ---------------------
Disclaimer: I don't really know if I got my facts right. I just
want to get more information.
Quote: Things are more like they are today than they've
ever been before.
- Dwight D. Eisenhower
# EOFeli@bbn.com (Steve Elias) (03/18/88)
In article <35092@kestrel.ARPA> king@kestrel.ARPA (Dick King) writes: >In article <22089@bbn.COM>, eli@bbn.com (Steve Elias) writes: ! ! and solar power satellites would be even bigger thermal ! ! offenders than solar cells on the ground. ! ! Actually no becuase the waste heat would be dissipated in space. actually yes! waste heat would be dissipated both in the atmosphere and on the ground. (microwave transmission). ! Tell me... If a plant per year had blown out like Chernobyl, would you ! believe an industry spokesman that attributed it to bad luck and said ! that you really should have had one blowout in two decades? No? I ! thought not. Why do you believe industry critics who claim that ! Chernobyl's should be happening each year, and that we've had ! incredibly GOOD luck so far? i believe this? thanks for letting me know. keep me informed. ! Cute little projects that make natural gas by biomass and that heat a ! few homes, or even a few hundred, abound. They are the darlings of ! the Lovins of the world. When one extrapolates to making a serious ! dent in energy requirements, one is quickly back to the era when ! everybody must be a farmer to supply the biomass. extrapolate if you like. my point stands: there are energy sources which do not upset the thermal balance of the planet. that's it. i'm talking about the greenhouse effect, not whatever your darling power source might be. that particular example, biomass, also has the benefit of using as much CO2 in the biomass process as is produced when the natural gas burns. closed cycle. (get some good chemistry dirt to tear this one apart, if you can!) ! Burning any fuel, except at a very low temperature, causes nitrous ! oxide. In fact, heating air to a high temperature in any manner has ! that effect. ah. get out the pliers... we'll get that bicuspid yet.
jfc@athena.mit.edu (John F Carr) (03/26/88)
In article <22285@bbn.COM> eli@BBN.COM (Steve Elias) writes: :In article <35092@kestrel.ARPA> king@kestrel.ARPA (Dick King) writes: ::In article <22089@bbn.COM>, eli@bbn.com (Steve Elias) writes: :: : and solar power satellites would be even bigger thermal :: : offenders than solar cells on the ground. :: Actually no becuase the waste heat would be dissipated in space. : actually yes: waste heat would be dissipated both : in the atmosphere and on the ground. (microwave transmission). But the initial thermodynamic inefficiencies would be in space; there would be inefficiencies on the ground, but these would be far less than the 60-70% waste of thermal plants now (and large solar power generators are thermal, not photoelectric). : extrapolate if you like. my point stands: there are energy sources : which do not upset the thermal balance of the planet. that's it. But these are just interesting footnotes to the main problem, unless it can be demonstrated that they can provide for a large part of future energy consumption. : i'm talking about the greenhouse effect, not whatever your : darling power source might be. that particular example, : biomass, also has the benefit of using as much CO2 in the biomass : process as is produced when the natural gas burns. closed cycle. : (get some good chemistry dirt to tear this one apart, if you can:) Assume that various biomass methods are used their greatest extent. Excerpts from a book which I recently posted figure biomass to be capable of providing about 2% of our energy needs. So, at great cost we reduce CO2 production by 2%. (Plants also have an oxidation cycle, which they use at night to burn the stored up sugars produced by photosynthesis; but I doubt this is important.) On the other hand if we replace coal with nuclear we reduce CO2 by about 20% (since much of the energy produced by fossil-fuels is not used for electricity, but by vehicles). A 2% change to man-made CO2 is not a lot; a 20% change is. John Carr "No one wants to make a terrible choice jfc@athena.mit.edu On the price of being free" -- Neil Peart
eli@bbn.com (Steve Elias) (03/27/88)
In article <4056@bloom-beacon.MIT.EDU> jfc@athena.mit.edu (John F Carr) writes: :In article <22285@bbn.COM: eli@BBN.COM (Steve Elias) writes: ::In article <35092@kestrel.ARPA: king@kestrel.ARPA (Dick King) writes: :::In article <22089@bbn.COM:, eli@bbn.com (Steve Elias) writes: : ::: : and solar power satellites would be even bigger thermal ::: : offenders than solar cells on the ground. : ::: Actually no becuase the waste heat would be dissipated in space. : :: actually yes: waste heat would be dissipated both :: in the atmosphere and on the ground. (microwave transmission). : :But the initial thermodynamic inefficiencies would be in space; there :would be inefficiencies on the ground, but these would be far less than :the 60-70% waste of thermal plants now (and large solar power generators :are thermal, not photoelectric). microwave solar power transmitters would indeed waste 50% of the power they collected... much of it by heating the atmosphere, and much of it by heating the power receivers and surrounding area on the ground. i'll try to find Drake's calculations which show this... i may have lots of free time soon. (i've already found another method of net access, thanks to a super-nice sysop).
glg@sfsup.UUCP (G.Gleason) (03/27/88)
In article <22285@bbn.COM> eli@BBN.COM (Steve Elias) writes: >In article <35092@kestrel.ARPA> king@kestrel.ARPA (Dick King) writes: >>In article <22089@bbn.COM>, eli@bbn.com (Steve Elias) writes: >! ! and solar power satellites would be even bigger thermal >! ! offenders than solar cells on the ground. >! Actually no becuase the waste heat would be dissipated in space. > actually yes! waste heat would be dissipated both > in the atmosphere and on the ground. (microwave transmission). Actually, it is quite a bit more complicated than this. First, conversion effeciency for microwave transmission is considerably higher (>50% (?75-85) vs 10-20% for solar cells). Of course this doesn't matter because the energy a satalite collects is in addition to the sunlight already hitting the earth, and then we have to consider the change in reflectivity by putting out solar panels (is it + or - ?). Don't forget to count the energy you put into building your earthbound collectors, which could be more than you get out in a lifetime (in space the energy is free for all practical purposes). In any case something seems bogus here, because in order to be significant we would have to be considering SPS's with a total area that is *very* large (significant relative to the earths total collection are). Gerry Gleason
eli@bbn.com (Steve Elias) (03/27/88)
In article <2963@sfsup.UUCP> glg@/guest4/glgUUCP (xt1112-G.Gleason) writes: >In article <22285@bbn.COM> eli@BBN.COM (Steve Elias) writes: (regarding solar power satellites) !! actually yes! waste heat would be dissipated both !! in the atmosphere and on the ground. (microwave transmission). ! !Actually, it is quite a bit more complicated than this. First, !conversion effeciency for microwave transmission is considerably !higher (!50% (?75-85) vs 10-20% for solar cells). Of course this !doesn't matter because the energy a satalite collects is in addition !to the sunlight already hitting the earth, and then we have to consider !the change in reflectivity by putting out solar panels (is it + or - ?). !Don't forget to count the energy you put into building your earthbound !collectors, which could be more than you get out in a lifetime (in space !the energy is free for all practical purposes). ! !In any case something seems bogus here, because in order to be significant !we would have to be considering SPS's with a total area that is *very* !large (significant relative to the earths total collection are). indeed something is bogus: the very idea of Solar Power Satellites being a useful energy source. they would be enormously expensive and enormously dangerous (thermally), if enough were built to actually provide a decent amount of energy. energy put into building earthside collectors is not leaving the earth/atmosphere system, so it doesn't negate the energy sent down by the power satellites. reflectivity changes due to the collectors would have to be considered, as well. but, regardless of reflectivity changes, thermal equilibrium would be quite goofed up -- by waste heat from the microwave receivers... the greenhouse effect can theoretically be kicked off by both CO2 buildup and by large thermal changes -- both factors are 'cause' and both factors are 'effect'. that's Frank Drake's point... i'm with him all the way on this one... just call me "thermally correct".
jfc@athena.mit.edu (John F Carr) (03/28/88)
In article <22670@bbn.COM> eli@BBN.COM (Steve Elias) writes: >In article <2963@sfsup.UUCP> glg@/guest4/glgUUCP (xt1112-G.Gleason) writes: : : (regarding solar power satellites) :!In any case something seems bogus here, because in order to be significant :!we would have to be considering SPS's with a total area that is *very* :!large (significant relative to the earths total collection are). : : indeed something is bogus: the very idea of Solar Power Satellites : being a useful energy source. they would be enormously expensive : and enormously dangerous (thermally), if enough were built to : actually provide a decent amount of energy. If we ever get a lot of energy out of them, we will need a cheaper launch system. We will also use very large thin films to minimize weight and cost. The SPS's will not be built if they are too expensive. (Assuming "thermally dangerous" refers to global, not local effects.) Whatever power generating capacity we need to build to keep up with demand, we will build. The relevant question is, what are the relative dangers of each type. Assuming international cooperation in space (else the SPS is too vulnerable to attack) the SPS is more reliable than other systems, and has a greater thermal efficiency on earth. (the efficiency of the space based part may not be high because of the difficulty of radiating heat, and that will affect the cost and possibly the decision whether to build). If the only criterion for choosing a generator were, "what is the danger to man, both short- and long-term", then solar power satellites would be a good choice. : energy put into building earthside collectors is not leaving the : earth/atmosphere system, so it doesn't negate the energy sent down : by the power satellites. reflectivity changes due to the collectors : would have to be considered, as well. but, regardless of reflectivity : changes, thermal equilibrium would be quite goofed up -- by waste heat : from the microwave receivers... You have assumed <= 50% efficiency, others have claimed higher. Either way, this is better efficiency than for a heat engine. So, it is better (if trying to minimize waste heat) to use solar power. : the greenhouse effect can theoretically be kicked off by both CO2 : buildup and by large thermal changes -- both factors are 'cause' and : both factors are 'effect'. that's Frank Drake's point... i'm with : him all the way on this one... just call me "thermally correct". The effect is far more sensitive to CO2 concentration; present power sources produce more CO2 as a fraction of the total present than they do heat. By the time we are generating a few % of the solar flux on the earth as waste heat, we will have to worry. By then, I hope we will have moved power intensive industry into space (if not, we can produce more power, and use the excess to drive a heat pump [perhaps, a large laser] and refridgerate the earth.) John Carr "No one wants to make a terrible choice jfc@athena.mit.edu On the price of being free" -- Neil Peart
laura@hoptoad.uucp (Laura Creighton) (03/28/88)
If you put up a big solar power sattelite and beam the power down to earth as microwaves, how on earth are you going to have radio communication on earth? I like my electromagnetic spectrum just the way it is right now, thank you. -- The universe is expanding, but I still can't find a parking space. Laura Creighton uunet!hoptoad!laura utzoo!hoptoad!laura sun!hoptoad!laura toad@toad.com
eli@bbn.com (Steve Elias) (03/28/88)
In article <4258@hoptoad.uucp> laura@hoptoad.UUCP (Laura Creighton) writes: >If you put up a big solar power sattelite and beam the power down to earth as >microwaves, how on earth are you going to have radio communication on earth? >I like my electromagnetic spectrum just the way it is right now, thank you. hey now! another good point... >The universe is expanding, but I still can't find a parking space. try parking your car in harvard yard. seriously! (harvard tickets are just crimson confetti -- you don't have to pay!)
jwm@stdc.jhuapl.edu (James W. Meritt) (03/28/88)
Reference the debate as to the efficiency of various energy conversion
methodologies and the thermal impact upon the environment:
It ALL winds up as heat in the environment, unless you directly radiate
it into space. Perhaps the original conversion is 30% (70% directly to
heat). Fine. Another couple of percent goes to heat during power
transmission, another big chunk goes to heat as you produce "useful work",
and then the "useful work" winds up as heat, too. Friction and such.
Everything winds up as heat, eventually. The percentages are just a
method of discovering how much is used along the way.
Disclaimer: Individuals have opinions, organizations have policy.
Therefore, these opinions are mine and not any organizations!
Q.E.D.
jwm@aplvax.jhuapl.edu 128.244.65.5jwm@stdc.jhuapl.edu (James W. Meritt) (03/28/88)
In article <22670@bbn.COM> eli@BBN.COM (Steve Elias) writes:
: indeed something is bogus: the very idea of Solar Power Satellites
: being a useful energy source. they would be enormously expensive
: and enormously dangerous (thermally), if enough were built to
: actually provide a decent amount of energy.
: energy put into building earthside collectors is not leaving the
: earth/atmosphere system, so it doesn't negate the energy sent down
: by the power satellites. reflectivity changes due to the collectors
: would have to be considered, as well. but, regardless of reflectivity
: changes, thermal equilibrium would be quite goofed up -- by waste heat
: from the microwave receivers...
You could always put them such they would intercept all that energy wasted
heating things like deserts,open ocean, political undesirables, war zones,
and other places best left in the dark!
;~) <== note smiley face! I'M KIDDING!!!!!!!
I just have problem with term "useful energy source". Maybe solution is
to move power-intensive operations (metal industry?) out of the earth/
atmosphere system?
Disclaimer: Individuals have opinions, organizations have policy.
Therefore, these opinions are mine and not any organizations!
Q.E.D.
jwm@aplvax.jhuapl.edu 128.244.65.5kent@xanth.cs.odu.edu (Kent Paul Dolan) (03/29/88)
In article <4258@hoptoad.uucp> laura@hoptoad.UUCP (Laura Creighton) writes: >If you put up a big solar power sattelite and beam the power down to earth as >microwaves, how on earth are you going to have radio communication on earth? >I like my electromagnetic spectrum just the way it is right now, thank you. But Laura, look on the bright side; put your eggs in a microwave rated dish, set them on the window ledge, and they'll fry in the waste heat. What could be more convenient? >The universe is expanding, but I still can't find a parking space. Well, if you'd ride a tachyon two-seater, so you arrive before you leave, you could just wait for yourself to go, and take that space. Nothing could be simpler if you plan ahead! Think of it as autocooperation. >Laura Creighton >uunet!hoptoad!laura utzoo!hoptoad!laura sun!hoptoad!laura toad@toad.com Kent, the man from xanth. (Yup, that is the original laura at hoptoad; accept no substitutes!)