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Reply #24: 20% planetary accretion, 80% radioactive decay [View All]

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bananas Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Jul-16-09 04:26 PM
Response to Reply #17
24. 20% planetary accretion, 80% radioactive decay
Geothermal gradient

The Earth's internal heat comes from a combination of residual heat from planetary accretion (about 20%) and heat produced through radioactive decay (80%).<2> The major heat-producing isotopes in the Earth are potassium-40, uranium-238, uranium-235, and thorium-232.<3>

It's still a trivial amount compared to solar influx:
Earth's energy budget

Incoming energy

The total flux of energy entering the Earth's atmosphere is estimated at 174 petawatts. This flux consists of:

* solar radiation (99.978%, or nearly 174 petawatts; or about 340 W m-2)
o This is equal to the product of the solar constant, about 1,366 watts per square metre, and the area of the Earth's disc as seen from the Sun, about 1.28 1014 square metres, averaged over the Earth's surface, which is four times larger. The solar flux averaged over just the sunlit half of the earth's surface is about 680 W m-2
o Note that the solar constant varies (by approximately 0.1% over a solar cycle); and is not known absolutely to within better than about one watt per square metre. Hence the geothermal and tidal contributions are less than the uncertainty in the solar power.

* geothermal energy (0.013%, or about 23 terawatts; or about 0.045 W m-2)
o This is produced by stored heat and heat produced by radioactive decay leaking out of the Earth's interior.

* tidal energy (0.002%, or about 3 terawatts; or about 0.0059 W m-2)
o This is produced by the interaction of the Earth's mass with the gravitational fields of other bodies such as the Moon and Sun.

* waste heat from fossil fuel consumption (about 0.007%, or about 13 terawatts; or about 0.025 W m-2) <1>.

There are other minor sources of energy that are usually ignored in these calculations: accretion of interplanetary dust and solar wind, light from distant stars, the thermal radiation of space. Although these are now known to be negligibly small, this was not always obvious: Joseph Fourier initially thought radiation from deep space was significant when he discussed the earth's energy budget in a paper often cited as the first on the greenhouse effect <2>.

We receive more energy each year from the sun than is stored in all the fissionable fuel underground even using reprocessing and breeder reactors:
World energy resources and consumption

The estimates of remaining worldwide energy resources vary, with the remaining fossil fuels totaling an estimated 0.4 YJ (1 YJ = 1024J) and the available nuclear fuel such as uranium exceeding 2.5 YJ. Fossil fuels range from 0.6-3 YJ if estimates of reserves of methane clathrates are accurate and become technically extractable. Mostly thanks to the Sun, the world also has a renewable usable energy flux that exceeds 120 PW (8,000 times 2004 total usage), or 3.8 YJ/yr, dwarfing all non-renewable resources.

When you look at how quickly we're burning through 0.4 YJ of fossil fuels, 2.5 YJ of nuclear fuel isn't going to last long, and that's assuming we can get breeder reactors to work reliably and economically. Without breeder reactors, it isn't even worth the trouble.

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  -Nuclear Bombshell: $26 Billion cost $10,800 per kilowatt! killed Ontario nuclear bid bananas  Jul-15-09 07:31 PM   #0 
  - Yes. When all the real costs of nuclear, including storage of waste,decommissioning,&true liability  lindisfarne   Jul-15-09 07:44 PM   #1 
  - We must never forget the pro-nukers have been lying to us for years now  madokie   Jul-15-09 07:49 PM   #3 
  - Yes, and now, even costs are being claimed to be trade secrets in attempts to obscure the truth.  lindisfarne   Jul-15-09 07:52 PM   #4 
  - Oh bull. The fact is that the dumb anti-nuke set is extremely unfamiliar with economics,  NNadir   Jul-15-09 08:05 PM   #5 
  - Did you read the link in OP? Also, in your calculations, did you include the actual  lindisfarne   Jul-15-09 08:08 PM   #6 
  - Big guy don't read links  madokie   Jul-15-09 10:16 PM   #10 
  - But they can unrec this issue  Liberation Angel   Jul-16-09 12:17 AM   #13 
  - nnadir never fails to entertain. nt  Javaman   Jul-17-09 12:07 PM   #35 
  - you don't need to store for tens of thousands of years.  Sirveri   Jul-16-09 12:28 AM   #14 
     - No, you have to store it for a million years - EPA requirement, based on NAS report  bananas   Jul-16-09 11:54 AM   #18 
     - EPA requirement is a smokescreen for the real reason.  Sirveri   Jul-17-09 01:29 AM   #30 
        - No, it wasn't a "smokescreen".  bananas   Jul-17-09 03:07 AM   #31 
           - Time will tell. But with the current state of US politics I see coal in the future.  Sirveri   Jul-17-09 04:54 AM   #32 
              - Oil is less than 2% of current electric generation.  kristopher   Aug-05-09 10:14 PM   #37 
     - You want mayonaise on that shit samwich  madokie   Jul-16-09 12:28 PM   #20 
        - tell that to the US Navy and France.  Sirveri   Jul-17-09 01:15 AM   #29 
           - It's easy to be anything one thinks they want to be here on the Internet  madokie   Jul-17-09 05:44 AM   #33 
              - Wow really, I had NO idea.  Sirveri   Jul-17-09 11:36 AM   #34 
  - Oh bull. The fact is that the dumb pro-nuke set is extremely unfamiliar with economics,  bananas   Jul-16-09 03:24 PM   #22 
  - What were the real costs of earlier non-nuclear power generation methods?  TheMadMonk   Jul-17-09 01:10 AM   #28 
  - 2-4-6-8 -- NUCLEAR POWER -- AIN'T IT GREAT?!?!  xchrom   Jul-15-09 07:45 PM   #2 
  - Nuclear energy is free- we have a giant nuclear reactor in the sky.  Ian David   Jul-15-09 08:57 PM   #7 
  - And it's responsible for wind powersolar power, and hydroelectric power. Not geothermal though-  lindisfarne   Jul-15-09 09:10 PM   #8 
     - For geothermal we can thank the other stars that supplied the material that made the Earth.  GliderGuider   Jul-15-09 10:05 PM   #9 
     - Geothermal energy is produced by nuclear fission  Dogmudgeon   Jul-16-09 10:40 AM   #16 
        - I doubt that nuclear reaction is responsible for geothermal energy..  TheCoxwain   Jul-16-09 11:49 AM   #17 
           - I think you've got your Uranium isotopes backwards...  SidDithers   Jul-16-09 11:59 AM   #19 
           - yup .. my bad .. clearly its been a while ..but I think that does not water my argument down  TheCoxwain   Jul-16-09 12:52 PM   #21 
           - 20% planetary accretion, 80% radioactive decay  bananas   Jul-16-09 04:26 PM   #24 
  - K&R and into the greatest page -- let's see if the unrec does it in  Liberation Angel   Jul-16-09 12:01 AM   #11 
  - UNWRECKER strikes again OFF Greatest page! Damn BUT see this:  Liberation Angel   Jul-16-09 12:16 AM   #12 
  - Only a shill would unrec this thread - they want to hide the true costs.  bananas   Jul-16-09 03:38 PM   #23 
  - They've got it down to three recs - they are really afraid of this information!  bananas   Jul-16-09 07:25 PM   #25 
     - It fits with the way it's been with the nuke crowd from the get go  madokie   Jul-16-09 07:34 PM   #26 
     - 3 recs is their goal  Liberation Angel   Jul-16-09 10:14 PM   #27 
  - No surprise.  girl gone mad   Jul-16-09 01:19 AM   #15 
     - Who knows the price? - nobody yet  DiamondJoe   Aug-05-09 03:47 PM   #36 
 

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