EPA GHGRP Subpart W Skill

Queries the EPA Envirofacts API for Greenhouse Gas Reporting Program (GHGRP) Subpart W data covering methane and CO2 emissions from petroleum and natural gas systems. Covers facilities since 2011 reporting year. No API key required.

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No Credential Required

The EPA Envirofacts API is fully public. No API key is needed for this skill.

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API Structure

Base URL: https://enviro.epa.gov/enviro/efservice/

The Envirofacts REST API follows a consistent pattern:

GET /enviro/efservice/{TABLE_NAME}/{COLUMN}/{OPERATOR}/{VALUE}/{FORMAT}
GET /enviro/efservice/{TABLE_NAME}/{COLUMN}/{OPERATOR}/{VALUE}/rows/{START}:{END}/{FORMAT}

• FORMAT: JSON, XML, or CSV
• Row ranges: rows/0:99 returns rows 0 through 99 (100 rows). Max ~10,000 per request.
• When OPERATOR is omitted, = is assumed: COLUMN/VALUE matches exact equality.

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Primary Tables for GHGRP Subpart W

PUB_FACTS_SUBPRT_GHG_W — Subpart W Facility Emissions

The main table for petroleum and natural gas system GHG emissions by facility and reporting year.

# All Subpart W facilities in West Virginia
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_SUBPRT_GHG_W/STATE_CODE/WV/JSON"

# WV facilities for a specific reporting year
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_SUBPRT_GHG_W/STATE_CODE/WV/REPORTING_YEAR/2022/JSON"

# Paginate: first 200 rows
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_SUBPRT_GHG_W/STATE_CODE/WV/rows/0:199/JSON"

# All Subpart W reporters for a single year (national)
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_SUBPRT_GHG_W/REPORTING_YEAR/2022/rows/0:999/JSON"

Key fields in PUB_FACTS_SUBPRT_GHG_W:

Field	Description	Example
FACILITY_ID	EPA GHGRP facility ID	1000244
FACILITY_NAME	Facility name	ANTERO RESOURCES WV
STATE_CODE	2-letter state	WV
COUNTY_FIPS	5-digit FIPS	54061
REPORTING_YEAR	Calendar year	2022
SUBPART_NAME	Subpart identifier	Subpart W
GHG_QUANTITY	Total GHG in mtCO2e	125432.5
GAS_NAME	Greenhouse gas name	Methane, CO2, Nitrous Oxide
EMISSION_SOURCE	Source category	Gathering and Boosting
LATITUDE_MEAS	Facility latitude	38.9271
LONGITUDE_MEAS	Facility longitude	-80.1234

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PUB_FACTS_FACILITY_GHG_EMITTER — All GHGRP Facilities

Broader table covering all GHGRP subparts, useful for finding a facility's ID before querying Subpart W detail.

# Find facility IDs for WV oil/gas operators
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_FACILITY_GHG_EMITTER/STATE_CODE/WV/rows/0:199/JSON" \
  | jq '.[] | {facility_id: .FACILITY_ID, name: .FACILITY_NAME, subpart: .SUBPART_NAME}'

# Find a specific facility by ID
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_FACILITY_GHG_EMITTER/FACILITY_ID/1000244/JSON"

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PUB_FACTS_FACILITY — Facility Metadata

Facility-level information including address, coordinates, and NAICS code.

# Get facility metadata by GHGRP ID
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_FACILITY/FACILITY_ID/1000244/JSON"

Key fields:

Field	Description
FACILITY_ID	GHGRP facility ID
FACILITY_NAME	Facility name
ADDRESS1, CITY, STATE	Mailing address
ZIP	ZIP code
LATITUDE_MEAS, LONGITUDE_MEAS	Coordinates
NAICS_CODE	Industry code (211120 = crude oil production, 211130 = natural gas extraction)
PARENT_COMPANY	Parent company name

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FLIGHT Tool (Manual Download)

For bulk analysis, the EPA FLIGHT (Facility Level Information on GreenHouse Gases Tool) provides downloadable CSVs:

• URL: https://ghgdata.epa.gov/ghgp/main.do
• Select: State, Subpart W, year range, Download CSV
• Fields: Facility, state, county, emissions by gas, by emission source category

This is the preferred route for multi-year trend analysis or national comparisons. The Envirofacts API is better for programmatic single-facility lookups.

Also: EPA GHGRP annual summary Excel files at: https://www.epa.gov/ghgreporting/ghg-reporting-program-data-sets

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Workflow

Step 1 — Resolve Intent

Map the user's question:

• "Methane emissions in [state]" → PUB_FACTS_SUBPRT_GHG_W/STATE_CODE/{STATE}/REPORTING_YEAR/{YEAR}/JSON
• "Top methane emitters in [basin]" → query state, parse GHG_QUANTITY, sort descending
• "Emissions from [operator]" → search by FACILITY_ID in PUB_FACTS_FACILITY_GHG_EMITTER
• "Emissions by equipment type" → filter on EMISSION_SOURCE field
• "Trend over time" → loop years 2011–2023, aggregate GHG_QUANTITY by year

Step 2 — Fetch Facility List

STATE="WV"
YEAR="2022"
curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_SUBPRT_GHG_W/STATE_CODE/${STATE}/REPORTING_YEAR/${YEAR}/rows/0:499/JSON" \
  | jq 'sort_by(.GHG_QUANTITY | tonumber) | reverse | .[0:20] | .[] | {
      name: .FACILITY_NAME,
      id: .FACILITY_ID,
      ghg_mtco2e: .GHG_QUANTITY,
      gas: .GAS_NAME,
      source: .EMISSION_SOURCE,
      county: .COUNTY_FIPS
    }'

Step 3 — Aggregate CH4 by Facility

A single facility-year appears in multiple rows (one per gas per emission source). Aggregate CH4 specifically:

curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_SUBPRT_GHG_W/STATE_CODE/WV/REPORTING_YEAR/2022/GAS_NAME/Methane/rows/0:499/JSON" \
  | jq '
    group_by(.FACILITY_ID) |
    map({
      facility: .[0].FACILITY_NAME,
      total_ch4_mtco2e: (map(.GHG_QUANTITY | tonumber) | add)
    }) |
    sort_by(.total_ch4_mtco2e) | reverse | .[0:15]
  '

Step 4 — Equipment Type Breakdown

The EMISSION_SOURCE field contains segment-level categories. Filter for one facility to see breakdown:

curl -s "https://enviro.epa.gov/enviro/efservice/PUB_FACTS_SUBPRT_GHG_W/FACILITY_ID/1000244/REPORTING_YEAR/2022/JSON" \
  | jq 'group_by(.EMISSION_SOURCE) | map({
      source: .[0].EMISSION_SOURCE,
      gas: .[0].GAS_NAME,
      total_mtco2e: (map(.GHG_QUANTITY | tonumber) | add)
    }) | sort_by(.total_mtco2e) | reverse'

Step 5 — Produce Output

Format a ranked facility table and equipment breakdown. Add CH4 mass conversion and basin-level context.

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Output Format

Facility Emissions Table

## EPA GHGRP Subpart W — Methane Emissions, WV (2022)

Top Reporting Facilities (CH4, tCO2e at AR4 GWP=25):

| Rank | Facility | County | CH4 (tCO2e) | CH4 (tonnes) | Primary Source | ID |
|------|----------|--------|-------------|--------------|----------------|----|
| 1 | ANTERO WV OPERATIONS | Doddridge | 485,230 | 19,409 | Gathering/Boosting | 1000244 |
| 2 | EQT PRODUCTION | Wetzel | 312,450 | 12,498 | Production | 1001876 |
| ... | ... | ... | ... | ... | ... | ... |

**Total WV Subpart W CH4 (2022):** X,XXX,XXX tCO2e (~X,XXX t CH4)

**Equipment Source Breakdown (WV, 2022, all gases):**

| Emission Source | CH4 (tCO2e) | % of State Total |
|----------------|-------------|-----------------|
| Gathering and Boosting | XXX,XXX | XX% |
| Production | XXX,XXX | XX% |
| Processing | XXX,XXX | XX% |
| Transmission Pipelines | XXX,XXX | XX% |

**Summary:** [narrative on basin-level emissions trends, top contributors,
year-over-year changes, comparison to national Subpart W totals, and any
notable equipment-type drivers]

**Data Caveats:** GHGRP captures facilities above 25,000 tCO2e/yr only.
Subpart W uses engineering calculations per 40 CFR Part 98 Subpart W, not
direct measurement. Actual emissions may differ. Latest available year is
typically the prior calendar year (data released ~9–18 months after year end).

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Subpart W Emission Source Categories

Subpart W covers six industry segments under 40 CFR Part 98 Subpart W:

Segment	Abbreviation	Key Equipment Sources
Production	W-P	Pneumatic controllers, wellhead equipment, completions, workovers, storage tanks
Gathering and Boosting	W-GB	Compressors, separators, dehydrators, pneumatics, pipeline leaks
Processing	W-PR	Compressors, dehydrators, acid gas removal, flaring
Transmission Pipelines	W-T	Compressors, metering stations, pipeline blowdowns
Distribution	W-D	City gate stations, distribution mains, service connections
Underground Storage	W-S	Compressors, well venting, flaring
LNG Storage	W-LNG	Liquefaction equipment, vaporizers

Largest Subpart W source nationally: Pneumatic devices (~35–40% of Subpart W reported CH4), followed by gathering compressors and storage tanks.

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CH4 Global Warming Potential Reference

Envirofacts reports emissions in metric tonnes CO2-equivalent (mtCO2e). To convert to physical methane mass:

CH4 mass (t) = CH4 (tCO2e) / GWP

GWP basis	CH4 GWP value	Context
AR4 (100-yr)	25	EPA GHGRP regulatory basis
AR5 (100-yr)	28	IPCC Fifth Assessment
AR6 (100-yr)	27.9	IPCC Sixth Assessment
AR4 (20-yr)	72	Short-term climate impact
AR6 (20-yr)	81.2	Short-term climate impact

Example: 100,000 tCO2e CH4 at AR4 = 100,000 / 25 = 4,000 metric tonnes CH4

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Error Handling

Condition	Meaning	Action
Empty JSON array []	No matching records	Try broader filter (remove year or state constraint); verify table name spelling
HTTP 500	Server error or malformed URL	Check table name case (must be UPPERCASE); verify column name exists
Rows appear duplicated	One row per gas per emission source	Aggregate by FACILITY_ID; filter GAS_NAME/Methane for CH4 only
GHG_QUANTITY is a string	Envirofacts returns all values as strings	Cast with tonumber in jq or float() in Python
Large result truncated	Envirofacts row limit	Use rows/0:N with pagination; try up to rows/0:9999
FACILITY_NAME mismatch	Exact match required for name filter	Use FACILITY_ID instead; find ID via FLIGHT tool CSV
Old data only	API lags 1–2 years behind current year	Note latest available year; for 2026 context, expect 2023 data

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National Context and Benchmarks

Metric	Value	Notes
Total U.S. GHGRP Subpart W	~175 MtCO2e/yr	~2022 reported total
Subpart W as % of U.S. GHG	~2.5–3.5%	EPA GHG Inventory
Production segment share	~35–40% of Subpart W	EPA analysis
Gathering & Boosting share	~30–35% of Subpart W	EPA analysis
GHGRP reporting threshold	25,000 tCO2e/yr	1,000 t CH4/yr at GWP 25
Appalachian basin states (WV+PA+OH)	~12–20 MtCO2e/yr combined	Marcellus/Utica plays

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Caveats and Data Limitations

• Reporting threshold: Only facilities emitting ≥25,000 tCO2e/yr must report. Small well pads, gathering lines, and marginal producers are exempt, creating significant under-coverage of distributed methane sources.
• Engineering calculations, not measurement: Subpart W allows facilities to calculate emissions using emission factors and throughput data rather than direct measurement. Independent atmospheric studies suggest actual emissions are 1.5–3x higher for some equipment categories.
• 2024 EPA methane rule (40 CFR Part 98 revisions, effective 2025): Expands monitoring requirements and revises emission factors. Reported values for 2025+ may show step-change increases reflecting improved methodology rather than actual emission increases.
• GWP basis: GHGRP uses AR4 GWP (CH4 = 25) for regulatory compliance. State and corporate inventories may use AR5 or AR6. Be explicit about which GWP is used when comparing values.
• Data lag: GHGRP data for year Y is typically released in fall of Y+1. As of March 2026, the most recent complete data is 2023.
• Offshore facilities: Subpart W covers OCS offshore platforms but they report differently. Use boem-offshore skill for offshore production context.