Cold Fusion was the popular name given to the phenomena of Low Energy Nuclear Reactions (LENR) . The LENR Phenoma was first discovered by Chemists Stanley Pons and Eugene Fleischman in 1988 .
Entrenched interests in the scientific community used badly biased testing protocols to attempt to discredit Pons and Fleishchman incredible discovery. If the discovery of the LENR phenomena has been validated billions of dollars in research funding for conventional technologies including those funds dedicated hot fusion research would have been immediately put at risk.
In spite of the attempt to discredit Pons and Felishchman's discovery, other researchers continued working on replication Pon and Fleischman's results by building new energy machines . It is worth noting that this ongoing research into the LENR phenomena was performed by scientists on "their own dime" largely without institutional sponsorship.
As a small core of researchers continued work in the field, and interest has increased significantly when in 2011 Andrea Rossi and Sergio Focardi first announced their results working with the Energy Catalyzer (E-Cat) machine. Rossi’s E-Cat has received a lot of attention because he was the first to publicly demonstrate his device and it has now been been tested by third parties, demonstrating at least ten times the energy of any known chemical reaction and showing that the E-Cat is capable of producing useful heat.
Rossi's E-Cat machine effectively proved the validity of the LENR phenomena. Physicist Dr. Tadahiko Mizuno later provided a theoretical basis for the LENR phenomena based entirely upon electro-magnetic forces:
https://www.amazon.com/Nuclear-Transmutation-Reality-Cold-Fusion/dp/1892925001/ref=sr_1_1
A number of start ups have now created working and viable Cold Fusion Energy machines:
https://e-catworld.com/what-is-lenr/
The incredible thing, hwover, is that the possibility of the LENR phenomena was actually first predicted by Nikola Tesla and his theory of electro-magnetism and the Zero Point field.
"All physical phenomena are electrical in nature....."
Nikola Tesla