What temperature range is considered “cold fusion”?
From the original article, this took place at approximately 70°C. I believe the difficulty here is proving the excess heat didn’t come completely from a chemical reactions.
From a practical standpoint the question is... can a configuration be found where the process will produce enough heat to make it worthwhile as an energy source?
“The process consisted of Arata and his co-researcher Yue-Chang Zhang, forcing deuterium gas under pressure into an evacuated cell. The cell contains palladium dispersed in zirconium oxide. Arata claims the deuterium is absorbed by the Palladium sample to produce dense or “pynco” deuterium. The deuterium nuclei are then close enough to fuse releasing heat and helium. After the injection of deuterium gas, the temperature rose to about 70 °C, which according to Arata was due to both chemical and nuclear reactions. With the gas turned off the temperature in the centre of the cell remained significantly warmer than the cell wall for 50 hours.”