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Renewable Natural Gas

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2 months 3 weeks ago - 2 months 3 weeks ago #34 by Kenny
Renewable Natural Gas was created by Kenny
I am trying to determine the emissions for compressed renewable natgas. Which natgas feedstock best reflects this in the Upstream Results HHV tab for 5.0d? Much thanks!
Last edit: 2 months 3 weeks ago by Kenny. Reason: compressed renewable natgas instead of renewable natgas

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2 months 2 weeks ago #35 by doconnor
Replied by doconnor on topic Renewable Natural Gas
Kenny

There are two RNG pathways in GHGenius 5.0D.

One if for Landfill Gas, this is in column BH on the Upstream Results sheet.

The other one if for an AD system and the results are in column BI. The feed recipe for the AS system can be varied on the input sheet and includes manure and crop residues. The crop residues can be switchgrass, hay, corn stover or wheat straw.

There is also the potential to use column BU, which is for a thermochemical pathway such as the gasification of wood residue.

I hope this helps.

Regards

Don O'Connor

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2 months 1 week ago #36 by Kenny
Replied by Kenny on topic Renewable Natural Gas
Hi Don,

Are you able to direct me how I can account for municipal organic waste as the input feedstock for the AD system within the RNG pathway? Much thanks!

Regards,

Kenny

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2 months 2 days ago #37 by doconnor
Replied by doconnor on topic Renewable Natural Gas
Kenny

There isn't a perfect pathway to do this in GHGenius, so you are going to have to use the AD RNG and make some adjustments to the results.

I would enter the quantity of feedstock as corn stover or wheat straw but ignore the fertilizer emissions that the model will produce.

LCAs are always done as a comparison between two systems. In this case you would want to account for the differences in the emissions between the business as usual case and the RNG case.

The waste is generated is both cases so you would only have to account for differences in transportation emissions between the material going to a landfill (I assume that is the current case) and the same feedstock going to an RNG system. If we assume that they are both the same, then there are no emissions to account for. If there are differences then enter the distance for the feedstock, but you might want to increase the distance to account for the difference in moisture content.

The power requirements are entered on the Input sheet and the other input is the methane leakage rate, which you will have to enter on the equipment emission sheet BR13. The default value is 1%.

The other big issue is what would the emissions have been from the landfill vs what they are from the RNG system. This is very site dependent and it is hard to provide any advice. If the landfill had no methane capture and destruction, then this could be a very large number.

I hope that this helps a little bit and I am sorry that it is not more straightforward.

Regards
Don O'Connor

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