| Cover | Jan. 28, 2025 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 28, 2025 |
| Entity File Number | 001-41306 |
| Entity Registrant Name | ALTERNUS CLEAN ENERGY, INC. |
| Entity Central Index Key | 0001883984 |
| Entity Tax Identification Number | 87-1431377 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 17 State Street |
| Entity Address, Address Line Two | Suite 4000 |
| Entity Address, City or Town | New York City |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10004 |
| City Area Code | (212) |
| Local Phone Number | 739-0727 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, par value $0.0001 per share |
| Trading Symbol | ALCE |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Elected Not To Use the Extended Transition Period | false |
