| Clue | Source | Date |
|---|---|---|
| Huffy electricity producers? (4,5) | The Guardian Quick | 11 Dec 2025 |
| Certain power plants | Universal | 25 May 2025 |
| Certain green energy producers | New York Times | 17 Mar 2019 |
| Certain green energy producers | ||
| Pollution-free power sources | ||
| Pollution-free power sources |