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

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

Kenny

The methane production per tonne of feedstock is not the input required, but the inverse is. One over the methane per tonne is tonnes (kg) per methane. A45 on the co-products sheet is for avoided methane emissions from the manure storage, so it is not what you are looking for.

The model has an input (F50 on the Input sheet) for the amount of landfill gas that is flared. this impacts the emissions in cell CY 17 on the Upstream emissions sheet. You could use this get the emissions for the BAU landfill case. The transportation emissions could be calculated using AM 79 ti 86 on the Input sheet and looking at CX 12 on the upstream sheet.

I hope this helps.

Regards

Don O'Connor

Kenny

On the Input sheet you enter the kg of feedstock (dry) required to produce one GJ of natural gas. AW 247 for manure, AW 246 for straw. For MSW, I would use the cell 246 and then ignore the feedstock recovery and fertilizer values that the model produces.

Regards
Don O'Connor

Kenny
That information is not available in GHGenius. If you want to look into landfill gas emissions I would suggest that you read the National Inventory Reports published by ECCC. They explain the methodology for determining LFG emissions.

Regards
Don O'Connor