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NG to LPG - why are feedstock transmission emissions zero?

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3 months 1 week ago #63 by zsoltvigh
Hi,

Could someone please explain to me why the feedstock transmission emissions for the NG to LPG case in the Upstream Results HHV tab are zero? In the latest GHGenius model, in cell N12 the emission factor is manually typed in as zero. How can there be no emission associated with piping the gas from the field to the plant gate where the gas will then be separated out into C3+ or C2+.

From practical experience, there should be emissions associated with running the compression equipment along the pipeline route along with any associated fugitive methane emissions that are released.

I am trying to calculate the upstream GHG emissions associated with producing natural gas in AB, fractionating the propane out in Fort Saskatchewan, and transporting it via rail ~ 3,000 km.

Thanks for the help!

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3 months 1 week ago #64 by doconnor
We do not have a data source that segregates that energy from the energy required to get the gas to the well head so we have to assume that the feedstock recovery energy includes the energy to move the gas from the well head to the gas processing plant.

Gas transmission energy in the model is about 1.5 g/km if that helps with the calculation.

Regards

Don O'Connor

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2 months 3 weeks ago #70 by zsoltvigh
Hi Don,

Thanks for your response. I am still unclear as to how the model treats the upstream emissions from the plant gate for natural gas. Am I right to conclude that there are no emission factors in the model for taking gas from the wellhead to the fractionator?

If so, the number you included in your response (1.5 g/km), is this per GJ of natural gas? and is this a CO2 eq number? if so which GWP potential is used to generate this number? Thank you for your help!

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2 months 3 weeks ago #71 by doconnor
Sorry that value doesn't make sense. I checked it again and the value in Alberta for gas transmission is 1.03 g CO2eq/GJ-km. That is using the 2007 GWPs where methane is 25.

Regards
Don O'Connor

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2 months 6 days ago #78 by zsoltvigh
Hi Don,

Would you be able to tell me the following:
1) Where I can find this 1.03 g CO2 eq/GJ-km in the model?
2) If it is too complicated, could you please provide the GHG emission profile broken down by component? (CO2, CH4, CO, N20) I am looking for the emission profile broken out by component as my model has various GWP optionalities built into it.

Thank you for your help!
Zsolt

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2 months 4 days ago #79 by doconnor
That value comes from the Upstream Emissions Sheet in cell DA12. The value is 618 g/GJ. The Alberta transmission distance is 600 km ( natural Gas Supply sheet, cell AI 337).

The individual gases on the Upstream sheet for CO2 from transmission are in cell DA 45 (589 g/GJ)
For CH4 they are in DA79, (1.2 g/GJ)
For N2O they are in cell DA96 (0.00338 gGJ)

All of these values would be divided by 600 to get g/GJ-km.

Regards
Don O'Connor

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