Cold fusion

Cold fusion is a nuclear fusion reaction that has been reported to occur near room temperature and pressure using relatively simple devices. In nuclear fusion, two nuclei are forced to join together to form a heavier nucleus, and during that process, energy is released.

Cold fusion is the popular term used to refer to what is properly called "low energy nuclear reactions" (LENR), part of the field of "condensed matter nuclear science" (CMNS).^[1] Cold fusion was brought into popular consciousness by the controversy surrounding the Fleischmann-Pons experiment in March 1989. Numerous research efforts at the time attempted and were unable to replicate these results.^[2] A panel organized by the U.S. Department of Energy concluded there was no convincing evidence that useful sources of energy would result from the phenomena attributed to cold fusion. By the mid-1990s, most governments and scientists had dismissed the concept as illusion.

In 2003, about 200 scientists were contributing to the field or participating in the international conferences on cold fusion.^[3] Independent replication of excess heat and other effects have been reported in specialized peer reviewed journals. The sophistication of calorimeters had made significant progress, a DOE panel observed in 2004, and evidence of power that cannot be attributed to ordinary sources was more compelling than in 1989. Still, its report said, many experiments were poorly documented, the magnitude of the effect had not increased, it was not easily repeatable, and a nuclear cause was generally rejected. The panel decided against a major federally-funded research program, and identified several areas of scientific inquiry that might resolve some of the controversies.

When water is electrolyzed in a closed cell surrounded by a calorimeter, we can account for all energy transfer using the theories of electricity, thermodynamics and chemistry: the electrical input energy, the heat accumulated in the cell, the chemical storage of energy and the heat leaving the cell balance out. When the cathode is made of palladium, and heavy water is used instead of light water, we expect to observe the same conservation of energy.

What Fleischmann and Pons said they observed, to their own astonishment, was that, in some cases, the heat measured by the calorimeter exceeded the expectations. They calculated a power density exceeding 1.000 watts/cm³ based on the volume of the cathode, a value too high to be explained by chemical reactions.^[4] As a consequence, they concluded that the effect must be nuclear, although they lacked evidence for it.

Others have tried to replicate the excess heat observations. Many failed, but some succeeded and reported high power densities in peer reviewed journals such as the Japanese Journal of Applied Physics and the Journal of Electroanalytical Chemistry.^[5]. Some researchers believe that the experimental evidences are sufficient to establish the scientific validity of the effect, but others reject those evidences, and the 2004 DOE review left the panel evenly split on the issue (a significant change compared to the 1989 panel which rejected all evidences).

The search of the products of nuclear fusion has resulted in conflicting evidences, leading two thirds of the DOE reviewers to exclude the possibility of nuclear reactions in these experiments in 2004. One additional reason for many to exclude a nuclear origin for the effect is that current physics theory cannot explain how fusion could occur in these experiments, and how the energy generated could be converted into heat (as opposed to radiation or other nuclear products). Still, in 2006, Mosier-Boss and Szpak, researchers in the U.S. Navy's Space and Naval Warfare Systems Center San Diego, reported unambiguous evidences of nuclear reactions, and a project has been set-up to facilitate its independent replication.^[6][7]

The US Patent Office accepted a patent in cold fusion in 2001.^[8] Still, current knowledge of the effect, if it exists, is insufficient to expect commercial applications soon. The 2004 DOE panel identified several areas that could be further studied using appropriate scientific methods.

The cold fusion researchers presenting their review document to the 2004 DoE panel on cold fusion said that the possibility of calorimetric errors has been carefully considered, studied, tested and ultimately rejected by cold fusion researchers. They explain that, in 1989, Fleischmann and Pons used an open cell from which energy was lost in a variety of ways: the differential equation used to determine excess energy was awkward and subject to misunderstanding, and the method had an error of 1% or less. Recognizing these issues, SRI International and other research teams used a flow calorimeter around closed cells: the governing equations become trivial, and the method has an error of 0.5% or better. Over 50 experiments conducted by SRI International showed excess power well above the accuracy of measurement. Arata and Zhang have observed excess heat power averaging 80 watts over 12 days. The researchers also said that the amount of energy reported in some of the experiments appears to be too great compared to the small mass of material in the cell, for it to be stored by any chemical process. Their control experiments using light water never showed excess heat.^[10] While Storms says that light water is an impurity that can kill the effect,^[11] Miley and others have reported low energy nuclear reactions with light water.^[12]

When asked whether the evidence for power that cannot be attribued to ordinary chemical or solid state source is compelling or inexistent, the 2004 DoE panel was evenly split. Many reviewers in the panel 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 of time of an experiment, that all possible chemical and solid state causes of excess heat have not been investigated and eliminated as an explanation, that the magnitude of the effect has not increased in over a decade of work, or that production over a period of time is a few percent of the external power applied and hence calibration and systematic effects could account for the purported effect.

Other evidences of heat generation not reviewed by the DOE include the detection of hot spots by infrared (see picture), the detection of mini-explosions by a piezoelectric substrate, and the observation of discrete sites exhibiting molten-like features that require substantial energy expenditure.^[13][14]

For a nuclear reaction to be proposed as the source of energy, it is necessary to show that the amount of energy is related to the amount of nuclear products. When asked about evidences of low energy nuclear reactions, two thirds of the 2004 DOE panel did not feel that there was any conclusive evidence, five found the evidence "somewhat convincing" and one was entirely convinced.

If the excess heat were generated by the hot fusion of two deuterium atoms, the most probable outcome, according to current theory, would be the generation of either a tritium and a proton, or a ³He and a neutron. The level of protons, tritium, neutrons and ³He actually observed in Fleischmann-Pons experiment have been higher than current theory asserts, but well below the level expected in view of the heat generated, implying that these reactions cannot explain it.

If the excess heat were generated by the hot fusion of two deuterium atoms into ⁴He, a reaction which is normally extremely rare, ⁴Helium and gamma rays would be generated. Miles et al. reported that ⁴helium was indeed generated in quantity consistent with the excess heat, but no studies have shown levels of gamma rays consistent with the excess heat.^[16] Current nuclear theory cannot explain these results. Researchers are puzzled that some experiments produce heat without ⁴Helium.^[17] Critics note that great care must be used to prevent contamination by helium naturally present in atmospheric air.^[18]

Although there appears to be evidence of anomalous transmutations and isotope shifts near the cathode surface in some experiments, cold fusion researchers generally consider that these anomalies are not the ash associated with the primary excess heat effect.^[19]

In 2006, nuclear activity was demonstrated by the use of standard nuclear track detectors made of CR-39. Photographs show scarring of the plastic disks, consistent with high energy nuclear radiation. The intensity and pattern of the scarring appears to rule out anomalous sources such as background radiation as the cause. The research was first presented at a science conference in Washington, D.C. on August 2, 2006.^[20] A detailed article appeared in New Energy Times, an online news magazine on November 10, 2006.^[21]

The cold fusion researchers presenting 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 when the proper conditions are reproduced, and that many of the reasons for failure to reproduce it have been discovered. Yet, most reviewers stated that the effects are not repeatable.

In 1989, the DOE panel said: "Even a single short but valid cold fusion period would be revolutionary. As a result, it is difficult convincingly to resolve all cold fusion claims since, for example, any good experiment that fails to find cold fusion can be discounted as merely not working for unknown reasons.".^[22] While repeatability is critical for commercial applications, independent reproduction is the criteria used by the scientific method.

Nobel Laureate Julian Schwinger said that it is not uncommon to have difficulty in reproducing a new phenomenon that involves an ill-understood macroscopic control of a microscopic mechanism. As examples, he gave the onset of microchip studies, and the discovery of high-temperature superconductivity.^[23]

Cold fusion's most significant problem in the eyes of many scientists is that current theories describing hot nuclear fusion cannot explain how a cold fusion reaction could occur at relatively low temperatures, and that there is currently no accepted theory to explain cold fusion.^[24][25] The DOE panel says: "Nuclear fusion at room temperature, of the type discussed in this report, would be contrary to all understanding gained of nuclear reactions in the last half century; it would require the invention of an entirely new nuclear process". Current understanding of hot nuclear fusion shows that the following explanations are not adequate:

• Nuclear reaction in general: The average density of deuterium in the palladium rod seems vastly insufficient to force pairs of nuclei close enough for fusion to occur according to mechanisms known to mainstream theories. The average distance is approximately 0.17 nanometers, a distance at which the attractive strong nuclear force cannot overcome the Coulomb repulsion. Actually, deuterium atoms are closer together in D2 gas molecules, which do not exhibit fusion.

• Absence of standard nuclear fusion products: if the excess heat were generated by the fusion of 2 deuterium atoms, the most probable outcome would be the generation of either a tritium atom and a proton, or a ³He and a neutron. The level of neutrons, tritium and ³He actually observed in Fleischmann-Pons experiment have been well below the level expected in view of the heat generated, implying that these fusion reactions cannot explain it.

• Fusion of deuterium into helium 4: if the excess heat were generated by the hot fusion of 2 deuterium atoms into ⁴He, gamma rays and helium would be generated. Again, insufficient levels of helium and gamma rays have been observed to explain the excess heat, and there is no known mechanism to explain how gamma rays could be converted into heat. Furthermore, the generation of ⁴He is always 10⁷ lower than that of tritium and proton for even the lowest energy of the incident deuteron measured so far.

In order for fusion to occur, the electrostatic force (Coulomb repulsion) that repels the positively charged nuclei must be overcome. Once the distance between the nuclei becomes comparable to one femtometre, the attractive strong interaction takes over and the fusion may occur. However, bringing the nuclei so close together requires an energy on the order of 10 MeV per nucleus, whereas the energies of chemical reactions are on the order of several electronvolts; it is hard to explain where the required energy would come from in room-temperature matter. Nuclei are so far apart in a metal lattice that it is hard to believe that the distant atoms could somehow facilitate the fusion reaction. Moreover, when fusion occurs, a large amount of energy is normally released as gamma rays or energetic protons or neutrons: there is no known mechanism that would release this energy as heat within the relatively small metal lattice.^[26] Robert F. Heeter said that the direct conversion of fusion energy into heat is not possible because of energy and momentum conservation and the laws of special relativity.^[27] Other critics say that until the observations are satisfactorily explained, there is no reason to believe that the effects have a nuclear rather than a non-nuclear origin.^[28]

The following mechanisms have been proposed to explain the discrepancies:

• Bose-Einstein condensate-like: Theoretical work suggests that deuterons in shallow potential wells such as may be found in a palladium metal lattice may exhibit a cooperative behaviour similar to a Bose–Einstein condensate ^{[citation needed]}. This would allow nuclei to react despite the coulomb barrier, due to quantum tunneling and superposition. However, traditional Bose condensates only occur at much lower temperatures (close to absolute zero).

• Mossbauer effect-like: Theoretical work suggests that the energy of fusion can be transmitted to the entire metal lattice rather than a single atom, preventing the emission of gamma rays ^{[citation needed]}. It is interesting to compare this to the Mossbauer effect, in which the recoil energy of a nuclear transition is absorbed by a crystal lattice as a whole, rather than by a single atom. However, the energy involved must be less than that of a phonon, on the order of ?? keV, compared with 23 MeV in nuclear fusion.

• Multi-body interactions: The following reaction, if proven to exists, would not generate gamma rays: d+d+d+d -> ⁸Be -> 2 ⁴He.^[29]

• Enhanced cross section; neutron formation; particle-wave transformation; resonance, tunneling and screening; exotic particles; formation of proton or deuteron clusters; formation of electron clusters.^[30]

• Deuterons embedded in palladium could settle at points and in channels within the metal's electron orbitals which substantially increase the likelihood of deuteron collisions.^[31] V.A. Filimonov and his colleagues in Russia have described this as a combination of deuteron cluster formation, shock wave fronts involving phase boundaries, and the directional propagation of solitons. (See also Zhang, W.-S. et al., 1999, 2000, and 2004.)

In 2005, Alan Widom and Lewis Larsen proposed a theory that could explain the experimental results without D-D fusion nor tunneling through a high Coulomb barrier. Based on mainstream physics, it proposes that electrons and protons annihilate to form low momentum neutrons, that these neutrons are absorbed by surrounding atoms, and that these atoms are transmuted by beta decay. ^[32]

Cold fusion researchers say that it could have a substantial economic impact, and help resolve global issues such as global warming or the risk of energy crisis. It could have advantages over plasma fusion (which has also not yet been developed for practical application) because it produces little ionizing radiation and can be scaled to small devices.^[33]

Cold fusion's commercial viability is unknown. The evidences of the excess heat effect are not accepted by a majority of scientists. If it exists, the effect would have to be thoroughly controlled before it could be safely scaled up to larger size for commercialization. Cells are orders-of-magnitude too small to be commercially viable (with typically less than a gram of material).^[34] Researchers have not yet discovered methods to prevent cathodes from deteriorating, cracking, and melting during the experiments. Additionally, all cold fusion experiments have produced power in bursts lasting for days or weeks, not for months as is needed for many commercial applications.

Skeptics say that commercial applications have been promised many times but never delivered.^[35] In 1995, Clean Energy Technology, Inc (CETI) demonstrated a 1-kilowatt cold fusion reactor at the Power-Gen '95 Americas power industry trade show in Anaheim, CA. They obtained several patents from the USPTO.^[36][37] As of 2006, no cold fusion reactor has been commercialized by CETI or the patent holders.

Companies publicly claiming to be developing cold fusion devices, include: Energetics Technologies Ltd. (Israel), D2Fusion, JET Thermal Products, Clean Energy Technologies, Inc. of Sarasota Florida (CETI), and ENECO of Salt Lake City.^[38] Ongoing developments concerning cold fusion commercialization efforts are tracked at peswiki. There are also some private cold fusion commercialization efforts that are rumored to be ongoing.^[39]

The idea that palladium or titanium might catalyze fusion stems from the special ability of these metals to absorb large quantities of hydrogen (including its deuterium isotope). The hydrogen or deuterium disassociate with the respective positive ions but remain in an anomalously mobile state inside the metal lattice, exhibiting rapid diffusion and high electrical conductivity. The special ability of palladium to absorb hydrogen was recognized in the nineteenth century.

In 1926, two German scientists, F. Paneth and K. Peters, reported the transformation of hydrogen into helium by spontaneous nuclear catalysis when hydrogen is absorbed by finely divided palladium at room temperature.^[40] These authors later retracted their report, acknowledging that the helium they measured was due to background from the air.

A year later, Swedish scientist J. Tandberg said 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 the 1960s, Fleischmann and his team started investigating the possibility that chemical means could influence nuclear processes. Quantum mechanics says that this is not possible, and he started research projects to illustrate inconsistencies of quantum mechanics, and the needs to use quantum electrodynamics instead. By 1983, he had experimental evidences leading him to think that condensed phase systems developed coherent structures up to 1000 Ångström in size, which are best explained by quantum electrodynamics. Impressed by the observation of "cold explosion" by Percy Williams Bridgman in the 30's, his team went on to study the possibility that nuclear processes would develop in such coherent structures.^[41]

In 1988 Fleischmann and Pons applied to the US Department of Energy for funding for a larger series of experiments: up to this point they had been running their experiments "out-of-pocket."

The grant proposal was turned over to several people for peer review, including 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. He had since turned his attention to the problem of fusion in high-pressure environments, believing it could explain the fact that the interior temperature of the Earth was hotter than could be explained without nuclear reactions, and by unusually high concentrations of helium-3 around volcanoes that implied some sort of nuclear reaction within. At first he worked with diamond anvils on what he referred to as piezonuclear fusion, but then moved to electrolytic cells similar to those being worked on by Fleischmann and Pons. In order to characterize the reactions, Jones had spent considerable time designing and building a neutron counter, one able to accurately measure the tiny numbers of neutrons being produced in his experiments. His team got 'tantalizingly positive' results early January 1989, and they decided in early February to publish their results.

Both teams were in Utah, and met on several occasions to discuss sharing work and techniques. During this time Fleischmann and Pons described their experiments as generating considerable "excess energy", excess in that it could not be explained by chemical reactions alone. If this were true, their device would have considerable commercial value, and should be protected by patents. Jones was measuring neutron flux instead, and seems to have considered it primarily of scientific interest, not commercial. In order to avoid problems in the future, the teams apparently agreed to simultaneously publish their results, although their accounts of their March 6 meeting differ.

In mid-March both teams were ready to publish, and Fleischmann and Jones had agreed to meet at the airport on the 24th to send their papers at the exact same time to Nature by FedEx. However Fleischmann and Pons broke that apparent agreement - they had submitted a paper to the Journal of Electroanalytical Chemistry on the 11th, and they disclosed their work in the press conference the day before. Jones, apparently furious at being "scooped", faxed in his paper to Nature as soon as he saw the press announcements.^[42]

The press reported on the experiments widely, and it was one of the front-page items on most newspapers around the world. The immense beneficial implications of the Utah experiments, if they were correct, and the ready availability of the required equipment, led scientists around the world to attempt to repeat the experiments within hours of the announcement.

On April 10, 1989, Fleischmann and Pons published their 8-page "preliminary note" in the Journal of Electroanalytical Chemistry. The paper was rushed, very incomplete and contained a clear error with regard to the gamma spectra. ^[43]]

On April 10 a team at Texas A&M University published results of excess heat, and later that day a team at the Georgia Institute of Technology announced neutron production.^{[citation needed]} Both results were widely reported on in the press. However, both teams soon withdrew their results for lack of evidence. For the next six weeks additional competing claims, counterclaims, and suggested explanations kept the topic on the front pages, and led to what some journalists have referred to as "fusion confusion."^[44]

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 Dr. Pons was scheduled to meet with representatives of President Bush early May.^[45]

On May 1 the American Physical Society held a session on cold fusion that ran past midnight; a string of failed experiments were reported. A second session started the next day with other negative reports, and 8 of the 9 leading speakers said that they ruled the Utah claim as dead. Dr. Steven E. Koonin of Caltech called the Utah report a result of "the incompetence and delusion of Pons and Fleischmann". The audience of scientists sat in stunned silence for a moment before bursting into applause. Dr. Douglas R. O. Morrison, a physicist representing CERN, called the entire episode an example of pathological science.^[46][47]

By the end of May much of the media attention had faded. This was due not only to the competing results and counterclaims, but also to the limited attention span of modern media.^{[citation needed]} However, while the research effort also cooled to some degree, projects continued around the world.

In July and November 1989, Nature published papers critical of cold fusion which cast the idea of cold fusion out of mainstream science.^[48][49]

In November, a special panel formed by the Energy Research Advisory Board (under a charge of the US Department of Energy) reported the result of their investigation into cold fusion. The scientists in the panel found the evidence for cold fusion to be unconvincing. Nevertheless, the panel was "sympathetic toward modest support for carefully focused and cooperative experiments within the present funding system".^[50] As 1989 wore on, cold fusion was considered by mainstream scientists to be self-deception, experimental error and even fraud, and was held out as a prime example of pseudoscience. The United States Patent and Trademark Office has rejected most patent applications related to cold fusion since then.

In July 1990, Fleischmann and Pons corrected the errors from their earlier "preliminary note," and published their detailed 58-page paper "Calorimetry of the Palladium-Deuterium-Heavy Water System," in the Journal of Electroanalytical Chemistry.

Also in 1990, Richard Oriani, professor of physical chemistry emeritus of the University of Minnesota published the first replication of the excess heat effect in his paper, "Calorimetric Measurements of Excess Power Output During the Cathodic Charging of Deuterium Into Palladium," in Fusion Technology.^{[citation needed]} This paper has never been challenged in the scientific literature.^{[citation needed]}

In 1991, Dr. Eugene Mallove said that the negative report issued by MIT's Plasma Fusion Center in 1989, which was highly influential in the controversy, was fraudulent because data was shifted^[51] without explanation, and as a consequence, this action obscured a possible positive excess heat result at MIT. In protest of MIT's failure to discuss and acknowledge the significance of this data shift, he resigned from his post of chief science writer at the MIT News office on June 7, 1991. He maintained that the data shift was biased to both 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.^[52]

Also in 1991, Nobel Laureate Julian Schwinger said that he had experienced "the pressure for conformity in editor's rejection of submitted papers, based on venomous criticism of anonymous reviewers. The replacement of impartial reviewing by censorship will be the death of science".^[53] He resigned as Member and Fellow of the American Physical Society, in protest of its peer review practice on cold fusion.

In 1992, the Wilson group from General Electric challenged the Fleischmann-Pons 1990 paper in the Journal of Electroanalytical Chemistry.^[54] The Wilson group asserted that the claims of excess heat had been overstated, but they were unable to "prove that no excess heat" was generated. Wilson concluded that the Fleischmann and Pons cell generated approximately 40% excess heat and amounted to 736 mW, more than ten times larger than the error levels associated with the data.

Despite the apparent confirmation by Wilson, Fleischmann and Pons still responded to the Wilson critique and published a rebuttal, also in the same issue of Journal of Electroanalytical Chemistry. ^[55] To this day, Fleischmann and Pons' seminal paper has never been refuted in the scientific literature. ^[56]

The 1990s saw little cold fusion research in the United States, and much of the research during this time period occurred in Europe and Asia. Fleischmann and Pons moved their research laboratory to France, under a grant from the founder of Toyota Motor Corporation. They sued La Repubblica, an Italian Newspaper, and its journalist for their suggestion that cold fusion was a scientific fraud, but lost the libel case in an Italian court.^[57] In 1996 they announced in Nature that they would appeal,^[58] but they didn't, perhaps because of the reply in Nature.^[59]

By 1991, 92 groups of researchers from 10 different countries had reported excess heat, tritium, neutrons or other nuclear effects.^[60] Over 3,000 cold fusion papers have been published including about 1,000 in peer-reviewed journals.^[61] In March 1995, Dr. Edmund Storms compiled a list of 21 published papers reporting excess heat. [69] Articles have been published in peer reviewed journals such as Naturwissenschaften, European Physical Journal A, European Physical Journal C, Journal of Solid State Phenomena, Physical Review A, Journal of Electroanalytical Chemistry, Japanese Journal of Applied Physics, and Journal of Fusion Energy.^[62]

The generation of excess heat has been reported by (among others):

• Michael McKubre, director of the Energy Research Center at SRI International,
• G. Preparata (ENEA (Italy))
• Richard A. Oriani (University of Minnesota, in December 1990),
• Robert A. Huggins (at Stanford University in March 1990),
• Y. Arata (Osaka University, Japan),
• T. Mizuno (Hokkaido University, Japan),
• T. Ohmori (Japan),

The most common experimental set-ups are the electrolytic (electrolysis) cell and the gas (glow) discharge cell, but many other set-ups have been used. Electrolysis is popular because it was the original experiment and more commonly known way of conducting the cold fusion experiment; gas discharge is often used because it is believed to be the set-up that provides an experimenter a better chance at replication of the excess heat results. The excess heat experimental results reported by T. Ohmori and T. Mizuno (see Mizuno experiment) have come under particular interest by amateur researchers in recent years.

Researchers share their results at the International Conference on Cold Fusion, recently renamed 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. Researchers have contributed hundreds of papers to an on-line cold fusion library.

Between 1992 and 1997, Japan's Ministry of International Trade and Industry sponsored a "New Hydrogen Energy Program" of $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."^[63]

In 1994, Dr. David Goodstein described the field as follows:^[64]

"Cold Fusion is 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."

Cold fusion researchers said that cold fusion is suppressed, and that skeptics suffer from pathological disbelief.^[65] They said that there is virtually no possibility for funding in cold fusion in the United States, and no possibility of getting published.^[66] They said that people in universities refuse to work on it because they would be ridiculed by their colleagues.^[67]

In February 2002, a laboratory within the United States Navy released a report that came to the conclusion that the cold fusion phenomenon was in fact real and deserved an official funding source for research. Navy researchers have published more than 40 papers on cold fusion.^[68]

In 2004, the United States Department of Energy (USDOE) decided to take another look at cold fusion to determine if their policies towards cold fusion should be altered due to new experimental evidence. They set up a panel on cold fusion. The nearly unanimous opinion of the reviewers 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 D/Pd systems, or whether or not D-D fusion reactions occur at energies on the order of a few 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.^[69]

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 (with some heat too). It was necessary to replenish the cell with heavy water at regular intervals. The cell was tall and narrow, so that 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.

A variety of other methods are known to effect "cold" nuclear fusion. Some are "cold" in the strict sense as no part of the material is hot (except for the reaction products), some are "cold" in the limited sense that the bulk of the material is at a relatively low temperature and pressure but the reactants are not.

• Fusion with low-energy reactants:
  • Muon-catalyzed fusion occurs at ordinary temperatures. It was studied in detail by Steven Jones in the early 1980s. It has not been reported to produce net energy. Because of the energy required to create muons, their 2.2 µs half-life, and the chance that muons will bind to new helium nuclei and thus stop catalyzing fusion, net energy production from this reaction is not believed to be possible.
• Fusion with high-energy reactants in relatively cold condensed matter: (Energy losses from the small hot spots to the surrounding cold matter will generally preclude any possibility of net energy production.^{[citation needed]})
  • Pyroelectric fusion was reported in April 2005 by a team at UCLA. The scientists used a pyroelectric crystal heated from −34 to 7 °C, combined with a tungsten needle to produce an electric field of about 25 gigavolts per meter to ionize and accelerate deuterium nuclei into an erbium deuteride target. Though the energy of the deuterium ions generated by the crystal has not been directly measured, the authors used 100 keV (a temperature of about 10⁹ K) as an estimate in their modeling.^[70] At these energy levels, two deuterium nuclei can fuse together to produce a helium-3 nucleus, a 2.45 MeV neutron and bremsstrahlung. This experiment has been repeated successfully, and other scientists have confirmed the results. Although it makes a useful neutron generator, the apparatus is not intended for power generation since it requires far more energy than it produces. ^{[71] [72] [73] [74]}
  • Antimatter-initialized fusion uses small amounts of antimatter to trigger a tiny fusion explosion. This has been studied primarily in the context of making nuclear pulse propulsion feasible. This is not near becoming a practical power source, due to the cost of manufacturing antimatter alone.
  • In sonoluminescence, acoustic shock waves create temporary bubbles that collapse shortly after creation, producing very high temperatures and pressures. In 2002, Rusi P. Taleyarkhan reported the possibility that bubble fusion occurs in those collapsing bubbles. As of 2005, experiments to determine whether fusion is occurring give conflicting results. If fusion is occurring, it is because the local temperature and pressure are sufficiently high to produce hot fusion.

• 2004 DoE panel on cold fusion
• Timeline of cold fusion
• Martin Fleischmann
• Stanley Pons
• Mizuno experiment
• Low energy nuclear reaction
• Biological transmutation
• Pathological science
• Pathological disbelief
• Huemul Project