2005-04-02

Global warming is not from waste heat

This is yet another myth I forgot, that GW might be due not to GHG's but to waste heat. This is not a totally stupid idea: back in the 1970's people considered it.

From this, global energy use in 1990 was 13.2 TW. It'll be a bit bigger now I suppose. So what is a terawatt? Its a billion kilowatts, err, so that makes it 1e12 watts. All of that ends up as waste heat somehow. I think the area of the earth is 4*1.3e14 m2. So the average global forcing is... 13.2e12/(4*1.3e14) = 0.025 W/m2. Compared to which, the well mixed GHG's are about 2 W/m2 TAR spm fig 3. So waste heat is about 1/80th of the GHG forcing. Which is clearly small globally, and probably so locally too.

11 Comments:

Anonymous Chas said...

I'm not sure that it is quite so small regionally or localy -the US burns about 25% of the worlds energy but isnt 25% of the area (~0.3 Watts/m2)
And within this region it is still not homogeneous (-San fransisco ~90 Watts/m2 ??)
See http://www.warwickhughes.com/hoyt/ffburning.htm

For fun:How many watts are emitted along the M1 per linear metre?

11:21 am  
Anonymous Anonymous said...

Another myth, not very common, is that there is not enough carbon dioxide in the atmosphere to have any effect on climate.

1:14 am  
Anonymous Anonymous said...

How about water, as I understand it water vapor is one of the strongest GHG, we are pumping billions of gallons from aquifers, possibly more than the oil we are pumping, that has not been part of the water cycle for thousands of years....

2:52 am  
Anonymous Anonymous said...

i hate the way rigfht wing nazis in america, say that sciebntists, who say global warming ios occuurring are just doing it for the money, do you really belive that sciebntists who treck all the way to antartica, and took geography as a university degree, atre doing it foer the money, the same people then etell us that nobody in america is a racists, and that nobiody in america is greedy, i am good enough to not belive dicjk cheny invaded iraq to make himself richer, but i am not dumb enough to think that if you own a oil buisness, you were not doing it to become rich, com eon, and surely scientists who know about these things are clever people, who have researched the subject, the more i raed about the right wing claim, that enviornmmental scisntsis are after money, and that th eleader of enron, was in no sense, a bad person, the more i realise the head of the christian right in america, is the devil, and the reopublican party, are his evil minions, and they will burn in hell for eterntity, with the cia puppet the pope. and the kaiser, and tsar nocholas, the vermin, anti-environmentalists, honesrtly want us to belive that people who are the heads of car companies, and billionares computer companies, are not in it for the money, but that geography studenmts, are just greedy people, apparently people who go to texas, and saudi arabia, to build oil wells, are not in it for the money, the only excuse they actually ever givem, is that it earsn allot of moneym, and geography students say they like geography, i know the devil will win as ever, and that they will sway us to beliove that geography students are geedym swine, just like bnurses, and that millionaire coal owners, are just nice people, who want to pour coal dust in all the rivers, as they are just so nice, just like rapists and murderers,

8:47 pm  
Anonymous Anonymous said...

I'm confused. According to EIA, the world energy consumption was 421 quadrillion BTU's in 2003. Based on conservation of energy laws, where did these Btu’s go? Answer: To Useful work (electricity, propulsion, motors, etc.); To Direct products (lubricants, asphalt, etc.); To Space heat, and To Waste heat.

My model assumes a source weighted average of 15% of this Total energy was transferred into the air directly. Any waste heat to water (e.g., power plant cooling) is assumed to NOT go directly into the this atmospheric model.

The troposhere is modeled to be 12000 meters high, have a humidity at 50%, and be well mixed.

A simple energy balance shows that 15% of 421 Quadrillion Btus into the above atmosphere will cause a 0.025 degree C temperature rise.

This is not negligible, especially if you think of the prior 100 years of contribution. Some amount was dissipated while some was energy was still contained in the atmosphere to be warmed more by the next year's waste sensible heat.

4:01 am  
Anonymous Anonymous said...

Interesting point. I'm looking forward to reading what the experts have to say.

9:42 pm  
Anonymous Küresel Isınma said...

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4:00 pm  
Anonymous Anonymous said...

Why only 15%. Nearly all energy ends up as waste heat in the atmosphere. You drive a car only 6% of the energy goes to moving the mass of the vehicle (F=ma bit). 80% is waste heat from the engine 6% is tyre rolling resistance = hot tyres heats the atmosphere, 6% aerodynamic drag heats the atmosphere the rest is other frictions which make the transmission and other things get hot which ends up in the atmosphere. Oh and then you stop so the 6% that you actually used to accelerate the vehicle is lost as heat in the brakes which ends up in the atmosphere. Thus 100% of the fuel energy ends up as heat in the atmosphere!

1:57 pm  
Blogger dave said...

please study the 3 laws of thermodynamics---i forget what they are---just kidding-----

where does energy go?

what is enthalpy?

Anonymous is correct

15 percent is wrong 100 percent of energy used becomes waste heat according to the the 3 laws of thermodynamics---look it up

4:59 am  
Blogger dave said...

the 3 laws of energy conservation are------someone please fill in the blanks

5:06 am  
Blogger dave said...

as a seperate issue ,,,as a mind exercise,,,how do you build a solar powered coal fired power plant

how many square miles is needed

to build the equivalent of a big truck going to across the usa,,burning 600 gallions of disel or more,,how many square miles of area would be needed to do the same work in solar energy?

We find that fossil fuels have a greater energy 'density' than do solar

I think that solar energy will be the answer,,solar plus fossil fuels
with all of us being more reasonable as to our usage

we do not need to make high intensity energy plastic and then throw that away

the total waste is equal to what humankind needs to have an adequate and good life

5:35 am  

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