Sounds like it’s reaching back to obscurity. 99.9% of the population never heard of cold fusion until 1989, so I’ll stick with that date as the best threshold.
Some references:
Source: Wikipedia
The ability of palladium to absorb hydrogen was recognized as early as the nineteenth century by Thomas Graham.[16] In the late 1920s, two Austrian born scientists, Friedrich Paneth and Kurt Peters, originally reported the transformation of hydrogen into helium by spontaneous nuclear catalysis when hydrogen was absorbed by finely divided palladium at room temperature. However, the authors later retracted that report, acknowledging that the helium they measured was due to background from the air.[16][17]
In 1927, Swedish scientist J. Tandberg stated that he had fused hydrogen into helium in an electrolytic cell with palladium electrodes.[16] On the basis of his work, he applied for a Swedish patent for “a method to produce helium and useful reaction energy”.[16] After deuterium was discovered in 1932, Tandberg continued his experiments with heavy water.[16] Due to Paneth and Peters’s retraction, Tandberg’s patent application was eventually denied.[16] His application for a patent in 1927 was denied as he could not explain the physical process.[18]
The final experiments made by Tandberg with heavy water were similar to the original experiment by Fleischmann and Pons.[19] Fleischmann and Pons were not aware of Tandberg’s work.[20][text 1][text 2]
The term “cold fusion” was used as early as 1956 in a New York Times article about Luis W. Alvarez’s work on muon-catalyzed fusion.[21] E. Paul Palmer of Brigham Young University also used the term “cold fusion” in 1986 in an investigation of “geo-fusion”, the possible existence of fusion in a planetary core.[22] However, Palmer and Jones used the term “piezonuclear fusion”, coined by Jones