BTU''S in a Pound of 100% Pure Carbon

 
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Post by lsayre » Mon. Oct. 10, 2016 7:32 am

Best I can tell, for those who are wondering, is that for all practical purposes there are 14,100 BTU's in a pound of 100% pure carbon.


 
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Post by tsb » Mon. Oct. 10, 2016 7:51 am

Larry,

How many pounds of oxygen does it take to burn a pound of pure carbon ?

 
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Post by lsayre » Mon. Oct. 10, 2016 7:59 am

C ~= 12
O ~= 16
O2 ~= 32
C + O2 ~= CO2
CO2 ~= 44

32/12 = 2.667

2.667 lbs. of oxygen are required to burn 1 lb. of carbon for the case of 100% pureness for each, as well as 100% combustion efficiency.

This process would generate 3.667 lbs. of CO2

By my guesstimation, 1 ton of typical (as delivered) anthracite should likely produce in the ballpark of roughly 6,200 lbs. of carbon dioxide for the case of extremely high combustion efficiency.

I saw some government figures which indicate that a ton of nominally 78% carbon coal produces 5.720 lbs. of carbon dioxide. I believe that typical anthracite (as delivered) is about 84% carbon by weight.
Last edited by lsayre on Mon. Oct. 10, 2016 9:57 am, edited 1 time in total.

 
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Post by lsayre » Mon. Oct. 10, 2016 8:29 am

Typical (as delivered) anthracite has about 12,300 BTU's per pound.

84% carbon x 14,100 BTU's for pure carbon = 11.844 BTU's

I assume the roughly 456 BTU difference (bonus) comes from burning the volatiles. By this ciphering roughly 3.7% of anthracites potential energy comes from volatile substances (combustible gases and solids) trapped within the coal.

 
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Post by McGiever » Mon. Oct. 10, 2016 9:35 am

lsayre wrote:C ~= 12
O ~= 16
O2 ~= 32
C + O2 ~= CO2
CO2 ~= 44

32/12 = 2.667

2.667 lbs. of oxygen are required to burn 1 lb. of carbon for the case of 100% pureness for each, as well as 100% combustion efficiency.

This process would generate 3.667 lbs. of CO2

By my guesstimation, 1 ton of typical (as delivered) anthracite should likely produce in the ballpark of roughly 6,200 lbs. of carbon dioxide for the case of extremely high combustion efficiency.

I saw some government figures which indicate that nominally 78% carbon coal produces 5.720 lbs. of carbon dioxide. I believe that typical anthracite (as delivered) is about 84% carbon by weight.
Holy Crap...At first I saw 6,200 lbs...that would be 3.1 tons of CO2 from just 1 ton coal. :o

 
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Post by lsayre » Mon. Oct. 10, 2016 9:56 am

McGiever wrote:Holy Crap...At first I saw 6,200 lbs...that would be 3.1 tons of CO2 from just 1 ton coal. :o
1 mole of O2 (oxygen in its normal state) is heavy stuff by comparison to 1 mole of carbon.

1 mole of O2 = 32 grams
1 mole of C = 12 grams
1 mole of C02 = 44 grams

BTW: There are 6.022×10^23 individual atoms or individual molecules (depending upon the nature of the substance) in one mole of any substance.
(Where 10^23 means 10 raised to the 23rd power. Or 10 multiplied times itself 23 times.)

 
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Post by McGiever » Mon. Oct. 10, 2016 10:49 am

lsayre wrote:C ~= 12
O ~= 16
O2 ~= 32
C + O2 ~= CO2
CO2 ~= 44

32/12 = 2.667

2.667 lbs. of oxygen are required to burn 1 lb. of carbon for the case of 100% pureness for each, as well as 100% combustion efficiency.

This process would generate 3.667 lbs. of CO2

By my guesstimation, 1 ton of typical (as delivered) anthracite should likely produce in the ballpark of roughly 6,200 lbs. of carbon dioxide for the case of extremely high combustion efficiency.

I saw some government figures which indicate that nominally (is this 1 pound ?)78% carbon coal produces 5.720 lbs. of carbon dioxide. I believe that typical anthracite (as delivered) is about 84% carbon by weight.


 
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Post by lsayre » Mon. Oct. 10, 2016 11:32 am

I went back and edited my post above to specify "ton".

One ton of anthracite generates about 3.1 tons of carbon dioxide.

 
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Post by McGiever » Mon. Oct. 10, 2016 12:18 pm

I'm going to need to install a bunch more solar panels to offset all the CO2 from the coal I burn. ;)

 
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Post by lsayre » Mon. Oct. 10, 2016 1:36 pm

For those who heat their homes with electricity, and if you assume that electricity is generated by roughly 33% coal and 33% natural gas, plus whatever other generating methods there are, then if you switch to burning coal directly to heat your own home, due to the overall power company inefficiencies in generating and then transmitting and distributing their electricity to you, your overall carbon footprint will almost assuredly go down.

Electricity from natural gas generates about 56% of the typical CO2 that electricity from coal produces. For both of these fuels the electricity generating efficiency of a modern power plant is about 40%. And that does not consider transmission and distribution losses. Roughly 6% of generated electricity is lost due to transmission and distribution.

Tell this to your friends when they call you a planet killer for heating with coal.
Last edited by lsayre on Mon. Oct. 10, 2016 2:07 pm, edited 1 time in total.

 
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Post by lsayre » Mon. Oct. 10, 2016 2:06 pm

EIA data for the average of our nations electrical power company generation in percentages by fuel source, dated April 1, 2016.

Coal = 33%
Natural gas = 33%
Nuclear = 20%
Hydropower = 6%
Other renewables = 7%
Biomass = 1.6%
Geothermal = 0.4%
Solar = 0.6%
Wind = 4.7%
Petroleum = 1%
Other gases = <1%

 
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Post by McGiever » Mon. Oct. 10, 2016 6:55 pm

Thanks for that Larry :)

Wow...Us residential Coal Burners are way Greener than your average Joe Electric User. 8-)

 
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Post by lsayre » Tue. Oct. 11, 2016 8:02 am

My average heating and DHW need during the 10 years that I heated with electricity was about 22,500 KWH (a figure which I have adjusted upward by 12% vs. actual to account for presently keeping our home 5 degrees warmer on average than when we heated with electricity). Back then I averaged (again with adjustment added to account for warmer house) ~29,500 KWH annually, with ~7,000 KWH going to everything but our heating and DHW.

29,500 - 7000 = 22,500 KWH for heat and DHW

22,500 KWH x 3,412 BTU/KWH = output 76,770,000 BTU's (which is also input BTU's due to electricities 100% efficiency).

76,770,000 output BTU's / 0.70 (my calculated overall coal boiler efficiency) ~= 110,000,000 input BTU's required from coal

110,000,000 input BTU's / 12,300 BTU/lb. ~= 8,950 lbs. anthracite needed annually to replace electricity.

8,950 lbs. / 2,000 lbs./ton ~= 4.5 tons anthracite

To this I must subsequently add 1 additional ton which I lose during the ~7 non-heating months just to keep the fire going in the boiler, and for no other practical use.

Total average coal burned annually ~= 5.5 tons

5.5 tons coal burned x 3.1 tons CO2 produced = 17 tons of carbon dioxide (which is my current annual carbon footprint).

In my next post to this thread I will attempt to estimate our electricity heated home and DHW carbon footprint.

 
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Post by lsayre » Tue. Oct. 11, 2016 8:32 am

Per the EIA, ~5,720 lbs. of CO2 are generated for every ton of coal consumed by the average of our nations electrical power plants. That's ~2.86 tons.

~1.6 tons of CO2 are generated by our nations electrical power plants that have substituted natural gas (for every ton of coal replaced by NG). That's 56% of what they used to generate with coal.

33% of electricity from coal, plus 33% from natural gas = 66% of all electricity is produced by these fuels.

Both coal plants and NG plants are about 40% efficient on average. Plus both lose 6% in transmission and distribution.

Call it 34% overall efficiency

To generate my needed 22,500 KWH they must effectively burn 22,500 x 0.66 / 0.34 = 43,676 KWH equivalent of combined coal and NG

43,676 KWH = 149,000,000 BTUH input for the power plant from combined coal and NG

Half of this is from coal and half is from NG

74,500,000 BTU from coal / ~12,300 BTU/lb. = 6,057 lbs. of coal = 3.0 tons

From natural gas the equivalence to this is 56%, so 56% of 3.0 tons = 1.7 tons

3.0 + 1.7 = 4.7 tons of coal equivalents in combined coal and NG

4.7 tons coal equivalent x 3.1 tons carbon dioxide per ton ~= 14.6 tons of CO2 generated annually by the power plant to supply my home with heat and DHW

The bottom line appears to be that whereas I presently generate 17 tons of CO2 annually, the average modern power plant would generate only 14.6 tons of CO2. That's 14% less CO2 than I generate.

Apparently my "assuredly" confident assumption as seen above stating that if you burn coal at home vs. getting electricity from a power plant you will lower your carbon footprint is incorrect (assuming that I have done all of this correctly, as I just did all of this completely on the fly while typing, and I did no proof checking).

But then again, if I didn't waste a ton of coal keeping my fire going during the non-heating months, the figures for CO2 generation at home and via a power plant would be much closer, as my summer wasted ton of coal = 3.1 tons of CO2.

17 - 3.1 = 13.9 tons of CO2, but the power plant will still have to generate 14.6 tons of CO2, so I would be ahead by 9.5%.

So in the end it appears that heating your home and providing for its DHW via coal vs. electricity during only the heating season will reduce your carbon footprint by roughly 9.5%.

 
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Post by McGiever » Tue. Oct. 11, 2016 8:56 am

You're on a roll there Larry (Numbers) :)

We solar guys get some carbon credits during the daylight hours too. :P


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