Cold fusion, sometimes called low energy nuclear reactions (LENR) or condensed matter nuclear science, is a set of effects reported in controversial laboratory experiments at ordinary temperatures and pressures; some researchers claim these effects are caused by nuclear reactions.
In 1989, Martin Fleischmann and Stanley Pons reported producing a tabletop nuclear fusion reaction at the University of Utah. In their press conferences and papers, they reported the observation of anomalous heating ("excess heat") of an electrolytic cell during electrolysis of heavy water using palladium (Pd) electrodes. Lacking an explanation for the source of such heat, they proposed the hypothesis that the heat came from nuclear fusion of deuterium (D). The report of their results raised hopes of a cheap and abundant source of energy.
Cold fusion gained a reputation as pathological science after other scientists failed to replicate the results. A review panel organized by the US Department of Energy (DOE) in 1989 did not find the evidence persuasive. Since then, other reports of anomalous heat production and anomalous Helium-4 production have been reported in peer-reviewed journals and have been discussed at scientific conferences. Most scientists have met these reports with skepticism. In 2004 the US DOE organized another review panel which—like the one in 1989—did not recommend a focused federally-funded program for low energy nuclear reactions. The 2004 panel identified basic research areas that could be helpful in resolving some of the controversies in the field. It stated that the field would benefit from the peer-review processes associated with proposal submission to agencies and paper submission to archival academic journals.
In 2007, a book and two peer-reviewed literature reviews presented the state of the research favorably.
In 1927, Swedish scientist J. Tandberg stated that he had fused hydrogen into helium in an electrolytic cell with palladium electrodes. On the basis of his work, he applied for a Swedish patent for "a method to produce helium and useful reaction energy". After deuterium was discovered in 1932, Tandberg continued his experiments with heavy water. Due to Paneth and Peters' retraction, Tandberg's patent application was eventually denied.
In their original set-up, Fleischmann and Pons used a Dewar flask (a double-walled vacuum flask) for the electrolysis, so that heat conduction would be minimal on the side and the bottom of the cell (only 5 % of the heat loss in this experiment). The cell flask was then submerged in a bath maintained at constant temperature to eliminate the effect of external heat sources. They used an open cell, thus allowing the gaseous deuterium and oxygen resulting from the electrolysis reaction to leave the cell, along with some heat. It was necessary to replenish the cell with heavy water at regular intervals. The authors said that, since the cell was tall and narrow, the bubbling action of the gas kept the electrolyte well mixed and of a uniform temperature. Special attention was paid to the purity of the palladium cathode and electrolyte to prevent the build-up of material on its surface, especially after long periods of operation.
The cell was also instrumented with a thermistor to measure the temperature of the electrolyte, and an electrical heater to generate pulses of heat and calibrate the heat loss due to the gas outlet. After calibration, it was possible to compute the heat generated by the reaction.
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 rose suddenly to about 50 °C without changes in the input power, for durations of 2 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.
In 1988, Fleischmann and Pons applied to the United States Department of Energy for funding towards a larger series of experiments. Up to this point they had been funding their experiments using a small device built with $100,000 out-of-pocket. The grant proposal was turned over for peer review, and one of the reviewers was Steven E. Jones of Brigham Young University. Jones had worked on muon-catalyzed fusion for some time, and had written an article on the topic entitled "Cold nuclear fusion" that had been published in Scientific American in July 1987. Fleischmann and Pons and co-workers met with Jones and co-workers on occasion in Utah to share research and techniques. During this time, Fleischmann and Pons described their experiments as generating considerable "excess energy", in the sense that it could not be explained by chemical reactions alone. They felt that such a discovery could bear significant commercial value and would be entitled to patent protection. Jones, however, was measuring neutron flux, which was not of commercial interest. In order to avoid problems in the future, the teams appeared to agree to simultaneously publish their results, although their accounts of their March 6 meeting differ.
In mid-March, both research teams were ready to publish their findings, and Fleischmann and Jones had agreed to meet at an airport on March 24 to send their papers to Nature via FedEx. Fleischmann and Pons, however, broke their apparent agreement, submitting their paper to the Journal of Electroanalytical Chemistry on March 11, and disclosing their work via a press conference on March 23. Jones, upset, faxed in his paper to Nature after the press conference.
On April 10, 1989, Fleischmann and Pons, who later suggested pressure from patent attorneys, published a rushed "preliminary note" in the Journal of Electroanalytical Chemistry. This paper notably contained a gamma peak without its corresponding Compton edge, a discrepancy that triggered accusations of fraud. Their "preliminary note" was followed up a year later in July 1990, when a much longer paper, going into details of calorimetry but without any nuclear measurements, was published in the same journal.
Also occurring on April 10, a team lead by John Bockris at Texas A&M University published their results of excess heat, followed up by a team at the Georgia Institute of Technology who observed production of neutrons. Both results were widely reported on in the press. The Georgia Institute of Technology team later retracted their announcement. For the next six weeks, additional competing claims, counterclaims and suggested explanations kept what was referred to as "cold fusion" or "fusion confusion" in the news.
On April 12, Pons received a standing ovation from about 7,000 chemists at the semi-annual meeting of the American Chemical Society. The University of Utah asked Congress to provide $25 million to pursue the research, and Pons was scheduled to meet with representatives of President Bush in early May.
Then on May 1, the American Physical Society held a session on cold fusion, which included several reports of experiments that failed to produce evidence of cold fusion. A second session began the next day with other negative reports, and eight of the nine leading speakers stated that they considered the initial Utah claim dead. Dr. Steven E. Koonin of Caltech described the Utah report as a result of "the incompetence and delusion of Pons and Fleischmann." Dr. Douglas R. O. Morrison, a physicist representing CERN, called the entire episode an example of pathological science.
In June 1989, John Bockris and his team at Texas A&M published their previously informal report of tritium generation. In september, they reported the sporadic observation of excess heat. In August, the state of Utah, which runs the University of Utah, invested $4.5 million to create the National Cold Fusion Institute. Nature published papers critical of cold fusion in July and November.
The panel "recommended against the establishment of special programs or research centers to develop cold fusion", but was "sympathetic toward modest support for carefully focused and cooperative experiments within the present funding system." The Panel recommended that "the cold fusion research efforts in the area of heat production focus primarily on confirming or disproving reports of excess heat" and stated that "investigations designed to check the reported observations of excess tritium in electrolytic cells are desirable.".
In June 1990, Gary Taubes wrote an editorial in Science suggesting that Texas A&M cells might have been spiked with tritiated water. A 3-professor panel of Texas A&M later found that none of the experiments were fraudulently conducted, saying that spiking was unlikely because scientists got different results when they tested the spiking theory by intentionally putting tritium in water. John Bockris later published his side of the controversy and a defense of academic freedom in "Accountability in Research".
In 1991, Dr. Eugene Mallove, a cold fusion proponent stated that the negative report issued by the MIT Plasma Fusion Center in 1989, which was highly influential in the controversy, was fraudulent because data was shifted without explanation, obscuring a possible positive excess heat result at MIT. In protest of MIT's failure to discuss and acknowledge the significance of this data shift, Mallove resigned from his post as chief science author at the MIT news office on June 7, 1991. He maintained that the data shift was biased to support the conventional belief in the non-existence of the cold fusion effect as well as to protect the financial interests of the plasma fusion center's research in hot fusion.
Also in 1991, researcher Andrew Riley was killed when a cold fusion cell exploded, possibly due to accumulation of deuterium gas and the failure of a safety valve.
Dr. Eugene Mallove contends that by 1991, 92 groups of researchers from 10 different countries had reported excess heat, tritium, helium4, neutrons or other nuclear effects. Proponents estimate that 3,000 cold fusion papers have been published, including over 1,000 journal papers and books, where the latter number includes both pro and con articles.
In 1992, workers at General Electric challenged the Fleischmann-Pons 1990 report in the Journal of Electroanalytical Chemistry, stating that the claims of excess heat had been overstated. The challenge concluded that the Fleischmann and Pons cell generated 40% excess heat, more than ten times larger than the initial error estimate. Despite the apparent confirmation, Fleischmann and Pons replied to General Electric and published a rebuttal in the same journal.
Fleischmann and Pons relocated their laboratory to France under a grant from the Toyota Motor Corporation. The laboratory, IMRA, was closed in 1998 after spending £12 million on cold fusion work.
Between 1992 and 1997, Japan's Ministry of International Trade and Industry sponsored a "New Hydrogen Energy Program" of US$20 million to research cold fusion. Announcing the end of the program, Dr. Hideo Ikegami stated in 1997 "We couldn't achieve what was first claimed in terms of cold fusion." He added, "We can't find any reason to propose more money for the coming year or for the future.
In 1994, Dr. David Goodstein described cold fusion as "a pariah field, cast out by the scientific establishment. Between [cold fusion] and respectable science there is virtually no communication at all. Cold fusion papers are almost never published in refereed scientific journals, with the result that those works don't receive the normal critical scrutiny that science requires. On the other hand, because the Cold-Fusioners see themselves as a community under siege, there is little internal criticism. Experiments and theories tend to be accepted at face value, for fear of providing even more fuel for external critics, if anyone outside the group was bothering to listen. In these circumstances, crackpots flourish, making matters worse for those who believe that there is serious science going on here."
Most people attempting to publish anything about the subject faced rejection of their papers. The late Nobel Laureate Julian Schwinger (1918 - 1994) was so outraged by the way the APS treated his papers that he resigned in protest. Cold fusion researchers said that cold fusion was being suppressed, and that skeptics suffered from "pathological disbelief". They said that there was virtually no possibility for funding in cold fusion in the United States, and no possibility of getting published. They said that people in universities refused to work on it because they would be ridiculed by their colleagues.
Researchers share their results at the International Conference on Cold Fusion, recently renamed the International Conference on Condensed Matter Nuclear Science. The conference is held every 12 to 18 months in various countries around the world, and is hosted by The International Society for Condensed Matter Nuclear Science, a scientific organization that was founded as a professional society to support research efforts and to communicate experimental results. A few periodicals emerged in the 1990s that covered developments in cold fusion and related new energy sciences (Fusion Facts, Cold Fusion Magazine, Infinite Energy Magazine, and New Energy Times).
In February 2002, the U.S. Navy revealed that its researchers had been studying cold fusion on the quiet more or less continuously since 1989. They built up a range of evidence that something strange happened when a current passed through palladium electrodes placed in heavy water. Researchers at their Space and Naval Warfare Systems Center in San Diego released a two-volume report, entitled "Thermal and nuclear aspects of the Pd/D2O system," with a plea for proper funding.
It concluded: "While significant progress has been made in the sophistication of calorimeters since the review of this subject in 1989, the conclusions reached by the reviewers today are similar to those found in the 1989 review." "The nearly unanimous opinion of the reviewers in the 2004 review was that funding agencies should entertain individual, well-designed proposals for experiments that address specific scientific issues relevant to the question of whether or not there is anomalous energy production in Pd/D systems, or whether or not D-D fusion reactions occur at energies on the order of a few electron volts (eV). These proposals should meet accepted scientific standards and undergo the rigors of peer review. No reviewer recommended a focused federally funded program for low energy nuclear reactions." "The reviewers believed that this field would benefit from the peer-review processes associated with proposal submission to agencies and paper submission to archival journals."
In 2007, a United States Naval Research Laboratory researcher with no previous experience with cold fusion wrote a review of experiments with solid palladium cathodes and electrolytes with deuterium, or with D2 gas loaded in palladium powders. The author said that more than 10 groups worldwide have reported the measurement of excess heat in 1/3 of their experiments and that most of the research groups have reported occasionally seeing 50-200% excess heat for hours to days. The difficulty of reproducing the research results were explained by the author as due to different research teams being able to achieve very different deuterium loading ratios within palladium.
In 2008, the government of India reviewed the field. Dr. M. R. Srinivasan, former chairman of the Atomic Energy Commission of India said: "There is some science here that needs to be understood. We should set some people to investigate these experiments. There is much to be commended for the progress in the work. The neglect should come to an end". On May 22, 2008, Arata and Zhang publicly demonstrated what they say is a cold fusion reactor at Osaka University.
Cold fusion has remained controversial, but several experimenters have reported excess heat, X-rays, gamma rays, neutrons, protons, helium-4, helium-3 , and/or anomalous isotopic distributions. A book and two peer-reviewed articles presented the state of the research in 2007.
In addition to Fleischmann and Pons, the generation of excess heat has been reported by others, including:
In 1993, Fleischmann reported "heat-after-death" experiments: he observed the continuing generation of excess heat after the electric current supplied to the electrolytic cell was turned off. Such observations have been reported by others.
The cold fusion researchers who presented their review document to the 2004 DOE panel said that "the hypothesis that the excess heat effect arises only as a consequence of errors in calorimetry was considered, studied, tested, and ultimately rejected". They said that numerous experiments conducted by SRI International showed excess power well above the accuracy of measurement. The researchers also said that the amount of energy reported in some of the experiments appeared to be too great compared to the small mass of the material in the cell for it to be stored by any chemical process. They said that their control experiments using light water did not show excess heat.
Numerous studies have found many kinds of radiation: alpha, beta, gamma, proton, triton. Such energetic radiation is not expected in the low energy environment typical of these experiments, and Storms says they cannot be dismissed as error. However, neutrons and other energetic emissions were never found in quantities commensurate with the excess heat, as would be expected by conventional fusion theory. This leads to the conjecture that the new process is somehow converting nuclear energy directly to heat
In 2007, the Space and Naval Warfare Systems Center San Diego reported their observation of pits in CR-39 detectors during D/Pd codeposition experiments in the European Physical Journal. They said that those pits have features consistent with those observed for nuclear-generated tracks, that the Pd cathode is the source of those pits, and that they are not due to contamination or chemical reactions. They attributed some pits to knock-ons due to neutrons, and said that other pits are consistent with those obtained for alpha particles.
Tadahiko Mizuno was among the first to contribute a paper and a book on the subject. Dr. Miley wrote a review of these experiments.
Iwamura and associates published what they say to be further evidence of transmutations in the Japanese Journal of Applied Physics in 2002. Instead of using electrolysis, they forced deuterium gas to permeate through a thin layer of caesium or strontium deposited on calcium oxide and palladium, while periodically analyzing the nature of the surface through X-ray photoelectron spectroscopy. They said that as the deuterium gas permeated over a period of a week, cesium appeared to be progressively transmuted into praseodymium while strontium appeared to be transmuted into molybdenum with anomalous isotopic composition representing an addition of four deuterium nuclei to the original nuclide. When the deuterium gas was replaced by hydrogen in control experiments, no transmutation was reported to be observed. The authors said that they analyzed, and then rejected, the possibility of explaining these various observations by contaminations or migration of impurities from the palladium interior.
In 2001, Di Giulio reported transmutations in a similar gas-loading experiment with Palladium.
The 2004 DOE panel noted that significant progress has been made in the sophistication of calorimeters since 1989. Evaluations by the reviewers ranged from: 1) evidence for excess power is compelling, to 2) there is no convincing evidence that excess power is produced when integrated over the life of an experiment. The reviewers were split approximately evenly on this topic.
Many of the reviewers noted that poor experiment design, documentation, background control and other similar issues hampered the understanding and interpretation of the results presented to the DOE panel. The reviewers who did not find the production of excess power convincing said that excess power in the short term is not the same as net energy production over the entire time of an experiment, that such short-term excess power is only a few percent of the total external power applied and hence calibration and systematic effects could account for the purported effect, that all possible chemical and solid state causes of excess heat had not been investigated and eliminated as an explanation, that the magnitude of the effect had not increased after over a decade of work.
The cold fusion researchers who presented their review document to the 2004 DOE panel on cold fusion said that the observation of excess heat has been reproduced, that it can be reproduced at will under the proper conditions, and that many of the reasons for failure to reproduce it have been discovered. Contrary to these assertions, most reviewers stated that the effects are not repeatable, the magnitude of the effect has not increased in over a decade of work, and that many of the reported experiments were not well documented.
New information was presented in 2004 to the DOE review panel regarding the production of 4He. When members of the panel were asked about the evidence of low energy nuclear reactions, twelve of the eighteen did not feel that there was any conclusive evidence, five found the evidence "somewhat convincing", and one was entirely convinced. The evidence of D+D fusion was taken as convincing or somewhat convincing by some reviewers; for others the lack of consistency was an indication that the overall hypothesis was not justified. Contamination of apparatus or samples by air containing 4He was cited as one possible cause for false positive results in some measurements.
An example of this was published by Clarke et al. in 2003. Their paper reported on the analysis of gases found in four ‘Case-type’ cells obtained from the McKubre group at SRI International, a primary cold fusion research group. The Abstract states: “One sample appears to be identical in composition to air, and the other three have been seriously affected by leak(s) into and from the SRI cells.” The Conclusions states: "The samples of gas from Case-type cells provided to us by the SRI workers do not show any evidence of production of 4He via cold fusion. Our analytical results can be explained by a combination of two factors: (a) severe leak(s) that allowed air into the cells, and also caused removal of gases including hydrogen from the cells to the atmosphere, and (b) the action of the Pd/C catalyst on O2 in the incoming air, which resulted in high CO and CO2 concentrations—telltale fingerprints of chemical combination of atmospheric O2 and C in the catalyst."
Cold fusion observations are contrary to the conventional physics of nuclear fusion in several ways :
Cold fusion researchers acknowledge these issues and have proposed various speculative theories (for a full review, see ) to explain the reported observations, but none has received mainstream acceptance.