Editing Cold fusion (section)

===Setup of experiments===
Cold fusion setups utilize an input power source (to ostensibly provide [[activation energy]]), a [[platinum group]] [[electrode]], a deuterium or hydrogen source, a [[calorimeter]], and, at times, detectors to look for byproducts such as helium or neutrons. Critics have variously taken issue with each of these aspects and have asserted that there has not yet been a consistent reproduction of claimed cold fusion results in either energy output or byproducts. Some cold fusion researchers who claim that they can consistently measure an excess heat effect have argued that the apparent lack of reproducibility might be attributable to a lack of quality control in the electrode metal or the amount of hydrogen or deuterium loaded in the system. Critics have further taken issue with what they describe as mistakes or errors of interpretation that cold fusion researchers have made in calorimetry analyses and energy budgets.{{citation needed|date=March 2021}}

====Reproducibility====
In 1989, after Fleischmann and Pons had made their claims, many research groups tried to reproduce the Fleischmann-Pons experiment, without success. A few other research groups, however, reported successful reproductions of cold fusion during this time. In July 1989, an Indian group from the [[Bhabha Atomic Research Centre]] ([[P. K. Iyengar]] and M. Srinivasan) and in October 1989, [[John Bockris]]' group from [[Texas A&M University]] reported on the creation of tritium. In December 1990, professor [[Richard Oriani]] of the [[University of Minnesota]] reported excess heat.{{sfn|ps=|Taubes|1993|pp=364–365}}

Groups that did report successes found that some of their cells were producing the effect, while other cells that were built exactly the same and used the same materials were not.{{sfn|ps=|Platt|1998}} Researchers who continued to work on the topic have claimed over the years that many successful replications had been made, but still had problems getting reliable replications.{{sfn|ps=|Simon|2002|pp=145–148}} [[Reproducibility]] is one of the main principles of the scientific method, and its lack led most physicists to believe that the few positive reports could be attributed to experimental error.{{sfn|ps=|Platt|1998}}<ref group="text" name="reger"/> The DOE 2004 report said among its conclusions and recommendations:

{{blockquote|text=Ordinarily, new scientific discoveries are claimed to be consistent and reproducible; as a result, if the experiments are not complicated, the discovery can usually be confirmed or disproved in a few months. The claims of cold fusion, however, are unusual in that even the strongest proponents of cold fusion assert that the experiments, for unknown reasons, are not consistent and reproducible at the present time. (...) Internal inconsistencies and lack of predictability and reproducibility remain serious concerns. (...) The Panel recommends that the cold fusion research efforts in the area of heat production focus primarily on confirming or disproving reports of excess heat.{{sfn|ps=|US DOE|2004}}}}

====Loading ratio====
[[File:Gas-ColdFusionCell-SRI-Intl-McKubre.jpg|thumb|upright|Michael McKubre working on deuterium gas-based cold fusion cell used by [[SRI International]]]]

Cold fusion researchers ([[Michael McKubre|McKubre]] since 1994,{{sfn|ps=|Simon|2002|pp=145–148}} [[Italian National Agency for New Technologies, Energy and Sustainable Economic Development|ENEA]] in 2011<ref name=ENEA_Magazin/>) have speculated that a cell that is loaded with a deuterium/palladium ratio lower than 100% (or 1:1) will not produce excess heat.{{sfn|ps=|Simon|2002|pp=145–148}} Since most of the negative replications from 1989 to 1990 did not report their ratios, this has been proposed as an explanation for failed reproducibility.{{sfn|ps=|Simon|2002|pp=145–148}} This loading ratio is hard to obtain, and some batches of palladium never reach it because the pressure causes cracks in the palladium, allowing the deuterium to escape.{{sfn|ps=|Simon|2002|pp=145–148}} Fleischmann and Pons never disclosed the deuterium/palladium ratio achieved in their cells;{{sfn|ps=|Huizenga|1993|p=82}} {{As of|2002|lc=y}} there were no longer any batches of the palladium used by Fleischmann and Pons because the supplier changed the manufacturing process,{{sfn|ps=|Simon|2002|pp=145–148}} and researchers still had problems finding batches of palladium that achieved heat production reliably.{{sfn|ps=|Simon|2002|pp=145–148}}

====Misinterpretation of data====
Some research groups initially reported that they had replicated the Fleischmann and Pons results but later retracted their reports and offered an alternative explanation for their original positive results. A group at [[Georgia Institute of Technology|Georgia Tech]] found problems with their neutron detector, and Texas A&M discovered bad wiring in their thermometers.{{sfn|ps=|Bird|1998|pp=261–262}} These retractions, combined with negative results from some famous laboratories,{{sfn|ps=|Browne|1989}} led most scientists to conclude, as early as 1989, that no positive result should be attributed to cold fusion.{{sfn|ps=|Bird|1998|pp=261–262}}{{sfn|ps=|Saeta|1999|loc= (pages 5–6; "Response"; Heeter, Robert F.)}}

====Calorimetry errors====
The calculation of excess heat in electrochemical cells involves certain assumptions.<ref>{{harvnb|Biberian|2007}} "Input power is calculated by multiplying current and voltage, and output power is deduced from the measurement of the temperature of the cell and that of the bath"</ref> Errors in these assumptions have been offered as non-nuclear explanations for excess heat.

One assumption made by Fleischmann and Pons is that the efficiency of electrolysis is nearly 100%, meaning nearly all the electricity applied to the cell resulted in electrolysis of water, with negligible [[Joule heating|resistive heating]] and substantially all the electrolysis product leaving the cell unchanged.{{sfn|ps=|Fleischmann|Pons|Anderson|Li|1990}} This assumption gives the amount of energy expended converting liquid D<sub>2</sub>O into gaseous D<sub>2</sub> and O<sub>2</sub>.{{sfn|ps=|Fleischmann|Pons|Anderson|Li|1990|loc=Appendix}} The efficiency of electrolysis is less than one if hydrogen and oxygen recombine to a significant extent within the calorimeter. Several researchers have described potential mechanisms by which this process could occur and thereby account for excess heat in electrolysis experiments.{{sfn|ps=|Shkedi|McDonald|Breen|Maguire|1995}}{{sfn|ps=|Jones|Hansen|Jones|Shelton|1995|p=1}}{{sfn|ps=|Shanahan|2002}}

Another assumption is that heat loss from the calorimeter maintains the same relationship with measured temperature as found when calibrating the calorimeter.{{sfn|ps=|Fleischmann|Pons|Anderson|Li|1990}} This assumption ceases to be accurate if the temperature distribution within the cell becomes significantly altered from the condition under which calibration measurements were made.<ref>{{harvnb|Biberian|2007}} "Almost all the heat is dissipated by radiation and follows the temperature fourth power law. The cell is calibrated ..."</ref> This can happen, for example, if fluid circulation within the cell becomes significantly altered.{{sfn|ps=|Browne|1989|loc=para. 16}}{{sfn|ps=|Wilson|Bray|Kosky|Vakil|1992}} Recombination of hydrogen and oxygen within the calorimeter would also alter the heat distribution and invalidate the calibration.{{sfn|ps=|Shanahan|2002}}{{sfn|ps=|Shanahan|2005}}{{sfn|ps=|Shanahan|2006}}