Using Renewable Fuel for Trucking

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2 years 4 months ago #377 by rockb
Using Renewable Fuel for Trucking was created by rockb
For the finished fuel transportation aspect of renewable fuel production, what would be the best way to account for the trucking emissions if using the renewable fuel in the truck for transportation? (Eg. producing hydrogen and shipping on truck powered by a portion of the produced hydrogen).

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2 years 4 months ago - 2 years 4 months ago #382 by rdo
Replied by rdo on topic Using Renewable Fuel for Trucking
I'm going to start off by admitting I hate to answer this because it's a feature we've talked about fleshing out, but it is not functional at the moment. There are two main ways to handle this problem one is easy and will give you a decent approximation of the total CI. The other is hard and accurate.

1. The easy way.

This method works best when the fuel use is lowest. So hydrogen is a perfect use case for this approximation. The basic idea is that we want to not include the transportation distance where the fuel is used, and we want to scale up the CI based on the "losses" of the hydrogen used in this way.

Not counting the transportation is easy. If say 30% of the trucks used in distribution are fuelled by your hydrogen, and the rest diesel, you could change the tonnes-shipped/tonnes-produced (input row 97) from 1.0 to 0.7. So we're still counting all the diesel trucks, the 70%, but none of the hydrogen trucks.

The second step is to gross up. There are a few ways to do this calculation. I'll describe how to do it from the bottom up. The data you need is how much hydrogen is used in the trucks for distribution vs how much is not. Let's say it's 95% sold to consumers and 5% used in the trucks. You want to divide all of your inputs, both energy and chemical, by 0.95. Effectively altering your energy and chemical yields.

2. The hard way.

I'm going to be specifying some more specific cells and assuming you're shipping liquid hydrogen. Generally the compressed hydrogen is one column further right. This is simply more complicated so I need to be more specific.

There exists in the model the skeleton of how to do this, but it's not consistently implemented. It tends to be implemented with canola or soy biodiesel as the assumed alternative fuel, but that can always be altered. I do not recommend doing this method, I am figuring this out on the fly and I can't be positive I'm not missing something that may contribute.

On the Transport sheet, in rows 86 and 87 we have values for how much of the truck shipping is via diesel vs how much is via an alternative fuel truck. Using our same 70% diesel and 30% hydrogen values, we would change BB86 to 0.7 and BB87 to 0.3. This sets 30% of our truck use to being "alternative fuel" based. At this point we should also change BB92, as it appears to be based on an LPG truck. In call BB92, instead of dividing by 'Vehicular Energy'!$C181, divide by 'Vehicular Energy'!$C171. If we were altering the CH2 pathway we would use cell C170 instead.

Now the Upstream Emissions HHV sheet needs to be altered. The hydrogen pathways all use the same fuel distribution formula in row 10. It's a bit more complicated than other cells because it can switch between LH2 or CH2. Within the formula are two specific terms we care about, the first is CH2 and the second is for LH2 distribution.
'Energy Use'!$K$139*'Exhaust Emissions'!$S$176
'Energy Use'!$J$139*'Exhaust Emissions'!$S$176

The first half of each term is our fraction of alt fuel use, and the second term is, in this case, the total lifecycle emissions for LPG trucks.

Onto Exhaust Emissions sheet. To continue being accurate but a pain to implement, we can create our own new formula in cell U176. For this we'll start by copying the formula that exists in cell F176, that is hydrogen from electrolysis.
='Vehicle Assembly'!H51+'Upstream Results HHV'!CP20+Q149/'Vehicular Energy'!E169
From this formula we can alter as we see fit. The Upstream Results CP20 cell should be moved to the column for your specific hydrogen. The other values should be fine as they are pointing to the active hydrogen in the model.

Back to Upstream Results HHV. Where we had Exhaust Emissions'!$S$176 before, change to Exhaust Emissions'!$U$176.

That should be it and provide accurate results on Upstream Results, Lifecycle Results, and LDV/HDV Summ sheets. I believe more alterations would be required to verify that Energy Balance is accurate.
Last edit: 2 years 4 months ago by doconnor.

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