Integrate fixed and variable operating cost estimates from NEMS

[zaneselvans]

Overview

Integrate estimates of fixed and variable operating costs from EIA's National Electricity Modeling System input data into PUDL so they can be accessed more easily.

EIA recently open sourced NEMS, including the previously somewhat guarded input data which includes estimates of fixed and variable operating costs for various types of generators based on their vintage and location. See these Excel sheets.

These values are used by many modelers as base-case assumptions for costs in the existing electricity system, and making them more accessible would save a bunch of tedious data management work downstream. @NicholasHRoy from RFF requested this data in #3662, but we know many others rely on it as well, including ourselves in the context of work done for Energy Innovation, LLC years ago.

Logistics

• Data is now publicly available and liberally licensed (Apache 2.0 license for the software it's part of)
• Data is available via EIA's NEMS GitHub repo.
• Data format is currently Excel spreadsheets.
• Data is unlikely to ever be updated again in this form -- since NEMS is undergoing a complete re-write.

What do you know about it so far?

Have not dug into the data in a long time, but when we worked with it in the EI context, the documentation of the process by which these FOM and VOM estimates were generated was definitely a bit sketchy. Would be worth revisiting