Electrical usage and the atmosphere

[Tomk]

Things bug me about global warming. I can't really put a finger on it exactly so I've been researching and trying to find out why I can't swallow a lot of it. Here is the result of some of my quick math.

I would file this under interesting trivia since, in the grand scheme of things, it means little.

A scientific fact is that electrical usage, no matter how it is used, always generates heat. 3.414 btu/watt to be exact. No not pi and yes I know the difference.

I wanted to find out how much heat is generated by our electrical usage in the US. This is at point of use so it doesn't matter how it was made. Coal, gas, wind, or solar will all have the same effect on the environment in this example since I'm not looking at the generation.

I found this site: http://www.eia.doe.gov/cneaf/electri...tablees1a.html

It says that in the month of OCT 2008 we generated 318,613 megawatts of power. So if we use my handy dandy formula we get:

1,087,744,782,000 BTUs of heat

So what the fuck does that mean?

Given a specific heat of .24 per pound of dry air @ 20 deg F this is enough heat to raise the temperature of 261,058,747,680 lbs of dry air one degree.

@20 deg F this equates to 21,754,895,640 cubic feet of air. Since one cu mile equals 27,878,400 cu ft. This comes out to roughly 780 cubic miles of air.

tl;dr
In Oct 2008 the US heated the equivalent of 780 cubic miles of our atmosphere 1 deg F simply by using electricity no matter how cleanly it was generated.

I am by no means a math type person so if I messed something up please let me know. There are definitely variables such as the fact that the atmosphere wasn't 20 deg and dry, but this at least gives me a ballpark idea.

[Akucaen]

It's the emissions from everything that are what people are on about. The heat generated by creation, transmission, and usage of electricity is akin to how you're killing the earth with CO2 by simply breathing. The emissions generated by the "creation" (altered matter states) of electricity is the problem.

[Khamsin]

Another thing to think about is, it doesn't matter how hot we make things at any given point in time. Hell, turning the heat on in your home or making a bonfire will heat the air more than simple electricity usage.

Why doesn't it matter? Because the heat can dissipate easily, and things go back to being cold. There's nothing to sustain the heat, and it's not a cumulative effect. The air doesn't keep getting 1 degree hotter and hotter per any unit of time. The air gets hot when the electricity is on, and cold when the electricity is off.

In the case of the greenhouse effect, heat is trapped inside the atmosphere due to certain gasses. Heat can build up and get hotter and hotter over time. That heat won't go away the moment you stop burning coal. It sticks around.

That's the argument behind why the greenhouse effect is dangerous. Whether or not we have a significant enough effect on it to detrimentally affect this planet's future is the topic of debate.

[Tristam]

First, we need to convert your btu calculation to Joules, for rounding purposes we'll say that the conversion yields 1000 trillion joules of energy, or 1x10^16 joules per month. For comparison, the energy from the sun provides ~2x10^17 joules per second, or ~5x10^24 Joules per month. This is why we're much more concerned with the balance between energy input from the sun and energy reflected or otherwise sent back out into space rather than energy derived from human activity. Also the atmosphere is something like 1x10^12 cubic miles.

[Kaylia]

Gonna add two comments that cover pretty much everything that need to be said... I think >_>

Renewable energy vs non renewable
Assuming you want to do the maths for a paper or something, you need to consider another factor.

Electricity that come from water, wind or solar energy don't change the amount of heat produced. Basically, you're just delaying heat creation by transforming those energies into electricity before retransforming them into another type of energy. Using energy that was stored for centuries deep inside the earth however "could" have an impact (it doesn't..well, not directly at least)


Energy produced by the sun reaching the Earth
This is the real answer to your question. The amount of energy received from the sun is on a completly different scale than the one produced by any other sources, including the Earth's core itself.

Using simple geometry (comparing the earth's surface to the distance from the sun), you can find the amount of energy that reach us P*(Pi*r²)/(4*Pi*d²)
P= intensity
r = Earth radius
d = Distance between sun and Earth


If you do the maths, it should give something around 1.7 x10^17 Watts (joules/seconds). Human electricity comsumption is around 5.67 x10^19 joules/years (according to wiki). So 1.8 x10^12 joules/seconds in average.


And all the stuff Khamsin said about heat being dissipated/trapped by greenhouse effect (I didnt want to repeat).


[edit1]
Something seem off with the number I used, I don't have time to check the maths, but they are easy to do anyway.

[Kaylia]

Hell, turning the heat on in your home or making a bonfire will heat the air more than simple electricity usage.

My computers beg to differ. It create lot of heat. Enough to actually keep the room at a temperature a few degree higher than anywhere else in the house.

[Tomk]

I did say in the beginning to view this as interesting trivia because it doesn't mean a whole hell of a lot in the grand scheme of things.

In fact since I used the values for an entire month and there is no way the energy would accumulate for that long without any dissipation, the effect dilutes greatly when viewed per day/hour/minute/second.

[Zosi]

Your (OP's) math is probably right, but you have to realize that 780 cubic miles is *tiny*. It's the equivalent of a region of air 28 miles by 28 miles by 1 mile, which is minuscule in comparison to the amount of land that it's actually distributed over. With that taken into account, the "electrical" heating effect ends up being a tiny fraction of a degree.

Edit: Typo'd the number.

[SephYuyX]

Global Warming is coming!

[Rammses]

The sun generates alot more heat than human activity does....

[Tomk]

It's extremely tiny, I agree.

Like I said in the op I'm not buying global warming yet. I just don't know why so I'm trying to get a handle of things.

I really think this is about as significant as cow farts and we are getting that shoved down our necks.

[Aerin]

CNN has some good links and info about the subject on its website.

Global Climate Change: News & Videos about Global Climate Change - CNN.com

Also curious as to why you're not "buying" it yet.

[Tomk]

So am I.


For example: lets look at cow farts. Scientists have studied it and said that cows produce more greenhouse gasses than even cars. That I can buy, I'm cool with that. But what does it mean?

The earth can only grow so much flora. We are only taking some of that and feeding it to cows instead of it dieing naturally. If those plants had died naturally, would they not have decayed and released the same amount of methane? It would just have been spread over large fields instead of concentrated in some cows ass.

For the record, I'm not against global warming. Call me on the fence.

[TheShadyMan]

Potentially Biased studies, and people looking for a profit by threatening the end of the world.

[Aerin]

Cows and cars make different greenhouse gases. Cows create Methane in their digestive system and fart it out. Cars just release Carbon Dioxide. I'm pretty sure the amount of CO2 released per year is a lot more than Methane from cows, but Methane is more harmful to the atmosphere.

When it comes to trees and deforestation, trees naturally store up a lot of CO2 which is what they breathe in. When they die they release it.

Then the ocean tries to soak up a lot of the CO2 being released. Since there's so much CO2 being released by us the ocean naturally soaks up more than it used to. This causes the water to become more acidic, which kills fish and coral reefs which aren't used to such a rapid change in acidity. Not to mention the change in temp.

[Rammses]

I really think this is about as significant as cow farts

Based on nothing. You have a preferred outcome for your research and that's why you're seemingly looking specifically for evidence supporting that preferred outcome. Bad idea.

As long as the heat generated by human activity is negligible in comparison to the heat generated by the sun, it will be a neglibile part of global warming. Some gases, greenhouse gases, can absorb some of the heat being radiated back towards space. This is a fact. The debate has been concerning what has caused the increased levels of these gases in the atmosphere, and also how much the greenhouse gases have affected the increase of temperature over the last 200 years, compared to other possible factors (Ice age - Wikipedia, the free encyclopedia).

[archibaldcrane]

If those plants had died naturally, would they not have decayed and released the same amount of methane?

Pretty sure the answer to that is no. Methane isn't a naturally occurring substance in cow feed (plants), it's produced via chemical reactions involved in digestion. I think.

[Tristam]

Potentially Biased studies, and people looking for a profit by threatening the end of the world.

Geeeeeeez,

Ok does everyone know that the NSF and NIH cap salary scales for people funded by taxpayer grants? No? Well now you do, scientist's don't get rich by doing global warming work.

[Boyiee]

I think Japan recently launched a satellite that can measure our ozone or something.

[Tristam]

I did say in the beginning to view this as interesting trivia because it doesn't mean a whole hell of a lot in the grand scheme of things.

In fact since I used the values for an entire month and there is no way the energy would accumulate for that long without any dissipation, the effect dilutes greatly when viewed per day/hour/minute/second.

oh ok, not to belittle your argument, but since you're interested in energy calculations I will say that one of the predictions made by AGW model for climate change is that a change in atmospheric CO2 levels will change the difference between the energy of Visible/UV light hitting the earth vs. the energy of infrared light reflected back into space i.e. less energy/heat headed back out into space. Since we've been measuring emitted infrared radiation edit: the difference (didn't mean to imply that up IR = up CO2) happens to correlate quite well with the rise in CO2.

Just one thing of many things, but it addresses your calculations.