Data & methodology

Station data

Source: the U.S. Department of Energy's Alternative Fuels Data Center station database, accessed through its public API. We request stations with fuel type biodiesel (BD), status open, access public, country US.

• The map on the homepage and state pages is AFDC's own widget. It reads the live database, which AFDC updates daily.
• State pages and site-wide counts are rebuilt from a fresh pull. Current pull: September 20, 2026 — 1,997 stations. We aim to refresh at least monthly; each state page prints its own pull date.
• Blend labels (B20, B99, “B20 in summer, B5 in winter”) are reproduced as AFDC records them. We group them into “B20 year-round,” “seasonal B20” and “B99/B100” for the summary tables only.

What the data leaves out

• AFDC lists only stations selling B20 or higher. Ordinary diesel containing up to 5% biodiesel (B5) is everywhere and isn't tracked.
• Private and fleet-only sites (municipal yards, cardlocks without public access) are excluded from our counts.
• AFDC confirms stations on a rolling basis, so an individual listing can be months old. State pages show the most recent confirmation date in the list. Call ahead before a long detour.
• There is no price data. For regional averages see the DOE's quarterly Alternative Fuel Price Report.

Editorial sources

Technical claims are tied to primary documents: ASTM D975, D7467 and D6751 (fuel specifications); the FTC Fuel Rating Rule, 16 CFR Part 306 (pump labels); manufacturer owner's manuals and service bulletins (engine approvals); Argonne National Laboratory's GREET model (lifecycle emissions); and the DOE/NLR Biodiesel Handling and Use Guide (storage, cold flow, materials compatibility). State incentive and mandate summaries link to the statute or the AFDC laws-and-incentives record.

Review and corrections

Articles show a “Reviewed” date, and we re-check OEM positions and state laws at least once a year, since both change. If you find an error, tell us; we correct the page and update the date. Station-level errors are best reported to AFDC directly so the fix reaches every site that uses the data.

Independence

The DOE, AFDC and the National Laboratory of the Rockies do not endorse or sponsor this site. Advertising is sold separately from editorial and never affects station listings.