---
kind: "unit"
title: "10"
title_heading: "Energy"
key: "chII/subchE/part504"
level: "part"
label: "Part 504"
heading: "Existing Powerplants"
release: "ecfr-current"
date: "2026-08-27"
url: "https://uscodex.org/cfr/10/chII-subchE-part504"
sections_count: 7
---

# Part 504 — Existing Powerplants

Title 10 C.F.R. — Energy › Chapter II — Department of Energy › Subchapter E — Alternate Fuels

## Sections

- [§504.2. Purpose and scope.](/cfr/10/504.2.md)
- [§504.3-504.4. Reserved](/cfr/10/504.3-504.4.md)
- [§504.5. Prohibitions by order (certifying powerplants under section 301 of FUA, as amended).](/cfr/10/504.5.md)
- [§504.6. Prohibitions by order (case-by-case).](/cfr/10/504.6.md)
- [§504.7. Prohibition against excessive use of petroleum or natural gas in mixtures—electing powerplants.](/cfr/10/504.7.md)
- [§504.8. Prohibitions against excessive use of petroleum or natural gas in mixtures—certifying powerplants.](/cfr/10/504.8.md)
- [§504.9. Environmental requirements for certifying powerplants.](/cfr/10/504.9.md)