Create natural gas combustion unit process report

[dt-woods]

As a test candidate, the natural gas combustion unit process (published on EDX) will be formatted into an HTML-based reporting template.

[dt-woods]

Review Notes: 2026-02-19 & 2026-02-20

• process name includes scenario (manually remove it)
• double-check about Gate-to-Gate (GG) vs Cradle-to-Gate (CG) boundary (it's GG)
• clarify process boundaries vs system boundary for NGI (replace language with "Unit Process Boundary")
• No inputs in the standalone UP (there should be 1 kg of natural gas product; figure out what the specific flow name should be).
• add a border around boundary image PNG (i.e., give the figure definition from the rest of the template)
• fixed output flows to have formulas (when possible); added
• fixed parameter table to read the markdown file; added
• add/update sources
  • 2019 Natural gas report (Littlefield)
  • 2025 Natural gas report (reference this one)
• note the UP OSTI link is https://doi.org/10.2172/1509357 (report)
• note that EDX has the link to the Excel, https://edx.netl.doe.gov/dataset/lca-up-combustion-of-natural-gas