Calculating coal CO2 emission intensity (kg CO2 emitted/kWh delivered)

Click For Summary

Discussion Overview

The discussion revolves around calculating the CO2 emission intensity from burning brown coal in a steam power plant. Participants explore the relationship between the carbon content of the coal, the efficiency of the power plant, and the resulting CO2 emissions, focusing on the theoretical aspects of combustion and energy conversion.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant presents the problem of calculating CO2 emission intensity based on the energy content and carbon content of brown coal, along with the efficiency of the power plant.
  • Another participant emphasizes the need for the original poster to attempt the problem before seeking help.
  • A participant expresses confusion regarding how carbon content affects the efficiency and energy output, calculating that 4.5 MJ of useful energy is obtained from burning 1 kg of coal.
  • Questions are raised about the amount of CO2 produced from burning 0.65 kg of carbon, leading to a mole calculation for CO2 production.
  • A calculation is presented indicating that burning 0.65 kg of carbon produces 2.38 kg of CO2, and there is a query about whether the energy delivered is simply 4.5 MJ or if it requires further consideration.
  • Another participant confirms the previous calculation of CO2 production and suggests that the energy output needs to be converted from MJ to kWh for the final answer.

Areas of Agreement / Disagreement

Participants generally agree on the calculations regarding CO2 production from carbon and the energy output from burning coal, but there remains uncertainty about the conversion of energy units and the final calculation of emission intensity.

Contextual Notes

There are unresolved aspects regarding the conversion from MJ to kWh and the implications of efficiency on the overall calculation of CO2 emission intensity.

darkPassenger
Messages
3
Reaction score
0
Hi all,

Would really appreciate some help on this problem I can't seem to figure out.

Brown coal has an energy content of 15MJ/kg, carbon content 65% by weight, burning in a 30% efficient steam power plant. Calculate the CO2 emission intensity (kg CO2 emitted/kWh delivered).Assume complete combustion where all the available carbon in the fuel is converted to carbon dioxide gas.

Thanks in advance :)
 
Engineering news on Phys.org
You need to at least make an attempt before anyone will help you. What do you know and what have you tried?
 
I'm getting confused about how the carbon content effects the efficiency i.e. the amount of energy obtained when the coal is burnt. Here's what I've come up with so far:

Brown coal: 15MJ/kg

Efficiency = power output/power input. --> 0.3 = x/15
x = 4.5 MJ. So after burning the coal we get 4.5MJ worth of useful energy/kg. Thus, 10.5MJ/kg is not useful. Would it be right to assume that this useless energy comes from the 650g of carbon in 1kg of coal? Don't know how to proceed after this.

Any help would be great, thanks :)
 
How much CO2 is produced from burning 0.65 kg Carbon?

What's the nuclear mass of carbon and oxygen?
 
Ok so C + O2 --> CO2
After a quick mole calculation, with C:CO2 in a 1:1 ratio I get 2.38 kg of CO2 produced from burning .65kg of Carbon. Would the kWh (energy) delivered by burning this coal just be 4.5MJ or is it something else?
 
darkPassenger said:
Ok so C + O2 --> CO2
After a quick mole calculation, with C:CO2 in a 1:1 ratio I get 2.38 kg of CO2 produced from burning .65kg of Carbon. Would the kWh (energy) delivered by burning this coal just be 4.5MJ or is it something else?

Yes, I think you're on the right track now. I think you're correct that burning 1 kg of coal produces 2.38kg of CO2 and 4.5 MJ of electrical energy. But you still need to convert 4.5MJ to kWh in order to get the final answer.
 

Similar threads

Replies
7
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
Replies
9
Views
2K
Replies
2
Views
9K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K