# Costing Assumptions

Hello,

In the WISDEM documentation cost model ‘A Detailed Wind Turbine Blade Cost
Model’ some values are assumed for cost of floor space (800\$/m2) and labour rates (20\$/h). Where are these assumptions from? Are they global averages or just snapshots from the US market from when the report was written (2019)?

Many thanks,
Connor.

Hello Connor,
these values came from domestic (US) blade manufacturers. Note that we will present some developments around advanced manufacturing of blades at AIAA SciTech 2023 and in that work we’ve been using \$35/hr of labor.
Best regards,
Pietro Bortolotti

Thanks Pietro.

Another question I had on the costing is on this equation from the virtual factory from the ‘Detailed Wind Turbine Cost Model’ report.

Could you explain the CT and Gating CT? The Gating CT is described as being assumed to be 24h but it’s not clear what it means.

And CT is not really described in the context of this equation so any information would be appreciated.

Best regards,
Connor.

Hello Connor,
cycle time is explained in page 14 of the report https://www.nrel.gov/docs/fy19osti/73585.pdf. Cycle time is the time it takes to complete an operation. Gating cycle time is the cycle time happening at the main mold, basically the bottleneck cycle time. The non-gating CT is all that CT that is needed but that can happen in parallel.
I hope this helps.
Best regards,
Pietro

Thanks Pietro.

I’m still struggling to recreate the example in the reference document. Perhaps I can walk you through what I’ve done and maybe you can see something I’ve missed.

I’m trying to recreate example 5.3 ‘SNL-100-03’ in the report. As I’m interested in the building costs right now, I’m trying to match the building costs results of \$2,951.68.

Here is my recreation following the steps in the report. I come to a conclusion of \$12,909 for building costs which is \$10k more than the example. Hopefully you can follow my calculations and provide any insights to something I’ve missed. Or perhaps link me to where the example is defined in more detal.

Many thanks,
Connor.

Hello Pietro,

Just following up with this question that I asked a few weeks ago.

Best regards,
Connor.

Hello Connor,
my apologies, I missed these messages completely. I’m afraid there is something wrong in the interpretation of the formula for floor space. In your notes you first sum L1s and L2s, and then you multiply them together. This is not what the report tried to say (my apologies if it’s confusing). The report tried to say to multiply each combination of L1 and L2, and then sum them together.
I would recommend checking the code implemented in WISDEM. The floor space is computed here WISDEM/blade_cost.py at fb7cddf67d21a12f1a8e04e98833f49a447af7bf · WISDEM/WISDEM · GitHub (and lines below). Also, I no longer have an input file for WISDEM for the SNL-100-03 blade, but you could try running one of the BAR models, for example the one provided in example 03 of WISDEM (WISDEM/examples/03_blade at master · WISDEM/WISDEM · GitHub). The BAR blades are exactly 100m long, so not too different from the SNL blade series.
I hope this helps, and again my apologies for the late reply.
Regards,
Pietro