Fleischmann and Pons electrolysisEdit
A constant current was applied to the cell continuously for many weeks, and heavy water was added as necessary. For most of the time, the power input to the cell was equal to the power that went out of the cell within measuring accuracy, and the cell temperature was stable at around 30 °C. But then, at some point (and in some of the experiments), the temperature reportedly rose suddenly to about 50 °C without changes in the input power, for durations of two days or more. The generated power was calculated to be about 20 times the input power during the power bursts. Eventually the power bursts in any one cell would no longer occur, and the cell was turned off.
Pons and Fleischmann also initially reported that a cell was generating 2.45 MeV neutrons at a rate three times the natural background rate. There was, however, no equipment directly measuring neutron energies, and this report was based on a mistaken inference from a gamma-ray spectrum. The most spectacular result they reported was that in one cell the most of the electrode melted and part of it vaporized, destroying the cell and the fume hood enclosing it.
In March, 2004, the U.S. Department of Energy (DOE) decided to review all previous research of cold fusion in order to see whether further research was warranted by any new results. The review document (PDF file) submitted to the DOE by the group of scientists who had requested a new review process states that "The experimental evidence for anomalies in metal deuterides, including excess heat and nuclear emissions, suggests the existence of new physical effects". It recognizes indirect evidence in support of the D + D → 4He + 23.8 MeV (heat) reaction, although the measurement of 4He quantity is imprecise.
The reproducibility of the result will remain the main issue in cold fusion research until an experiment is designed which is fully reproducible by following a clear recipe, and which preferably generates power continuously rather than sporadically and does so in a way that cannot be attributed to experimental defects.