[FiatLuxDave]

It's been about 25 years since I hung out on Usenet sci.physics.fusion, where there was a lot of debate about cold fusion/LENR back in the day. I remember that the most likely theory I saw was that the extra energy (aside from the widespread calorimetry errors) was coming from the pressure of deuterium within the palladium matrix. It takes hundreds of thousands of psi to load the palladium with deuterium. If you pressurized a scuba tank slowly with thousands of psi, then released the gas in bursts, you'd see a constant energy input with bursts of "excess" energy output, just like cold fusion experiments report. The fact that experimenters using pre-loaded electrodes were more likely to observe "excess" energy seems to corroborate this theory.

Are you aware of any experiment proving or disproving this theory?

Here is a relevant experiment, albeit aimed towards energy storage: http://news.stanford.edu/news/2014/september/battery-palladi...