Low Energy Nuclear Reaction research continues on the fringes
On 23 March 1989, Stanley Pons and Martin Fleischmann made an astonishing announcement: they claimed to have achieved nuclear fusion — the power of the Sun — in a test tube of water at room temperature.
What followed was a media blitz. In the wake of the Exxon Valdez disaster and Chernobyl, the promise of limitless, safe energy had enormous appeal. But it was not to be. As other scientists failed to replicate their results and more and more questions arose about how they arrived at their findings, the subsequent scandal destroyed any chance for cold fusion research being taken seriously by the scientific community. Likened to perpetual motion machines, cold fusion was too hot to touch.
The theory behind fusion is relatively simple. Fusion is a process by which atomic nuclei, formed of protons and neutrons, overcome their natural electromagnetic repulsion to fuse into higher elements and release energy in the process. The fusion requires that the nuclei be forced close enough together that the strong force overcomes the electromagnetic force.
For fusion to take place as it does inside the Sun, extreme heat and pressure is needed to cause hydrogen fuel to become so energetic that the fuel collides and fuses, releasing energy. Hydrogen bombs work this way also, using a nuclear fission reaction to catalyze the fusion reaction.
Cold fusion has little to do with being cold. Instead, it has to do with not being hot. The idea is that instead of using extreme heat to smash fuel together, you can use other electromagnetic forces to overcome the nucleus’s natural repulsion and force them together. The approach Pons and Fleishmann took was to take some fuel, such as deuterium (D) atoms, pull them into a lattice of metallic palladium (Pd) atoms using the application of an electric current. The lattice is a tight squeeze for the atoms so some of them are encouraged to fuse together. At least that was the theory.
The two scientists thought they had detected some of the products of nuclear fusion and rushed to publish the findings. These later had to be retracted when it was clear that their findings could not be reliably reproduced. Moreover, the products of nuclear fusion were not present.
The fuel they used, deuterium, is just an isotope of hydrogen. It has one proton and one electron but also one neutron, a neutral subatomic particle. Deuterium fuses more easily than hydrogen and so it is typically used as a fuel. It is present in vast quantities in the ocean as “heavy water” or D2O (as opposed to H2O), so if it could be harnessed as fuel, the possibilities for energy production are almost limitless.
A deuterium + deuterium reaction produces three possible outcomes:
Hydrogen and tritium atoms, meaning one neutron has moved from one of the the deuterium atoms to the other
A neutron and a Helium-3 atom, meaning the proton and electron has moved from one atom to the other.
Helium-4 and a gamma ray, meaning that the two deuterium atoms have combined and released some radiation.
Experimenters were unable to detect any of the byproducts of these fusion reactions, including the gamma rays which P&F reported to have found. The excess energy they claimed was produced was later dubbed the Fleishmann-Pons Effect (FPE), but was widely considered to be experimental error.
Despite the failure to demonstrate fusion, many scientists reproduced the FPE effect. These results however were far from reliable and so there was skepticism that it was real.
In recent years, the claim that energy production is being observed in these reactions has never wavered in the community of scientists researching it, but many have distanced themselves from the phrase “cold fusion”.
These reactions, now dubbed Low Energy Nuclear Reactions (LENR), are considered to be nuclear in nature because the energy production observed, e.g., 150 watts out for 100 watts in, is higher than a chemical reaction could explain.
Indeed, hundreds of experiments, based on a 2010 analysis by Storms, have now demonstrated the production of excess heat. Dozens have shown transmutation of elements and tritium production, but few have demonstrated other products of nuclear fusion such as Helium-4. Since Helium-4 can be present from atmospheric contamination, it is reasonable to dismiss these as not fusion products.
A major force in the United States behind the continued interest in LENR is the U. S. Defense Department, particularly the Navy which depends on large, expensive, and dangerous nuclear reactors to power submarines and aircraft carriers. Even a possibility of having a reliable, portable source of power is enough for it to put some research dollars behind it.
Indeed, work at the Space and Naval Warfare Center (SPAWAR) in San Diego, California has demonstrated the ejection of nuclear products in experiments with the same type of palladium lattice that P&F used. This included the use of a special kind of plastic called CR-39 which can be used to capture ejected subatomic particles.
The researchers passed an electric current through a solution of deuterium containing a palladium lattice with a gold-nickel cathode and produced an immediate reaction. Examining the CR-39 with a microscope, they saw tell-tale “triple tracks” indicating neutrons had smashed into the plastic.
As one of the study participants, Pam Mosier-Boss said, “People have always asked ‘Where’s the neutrons? … We now have evidence that there are neutrons present in these LENR reactions.”
In a paper from 2007, this same team described the theory behind the neutron production, called electron capture, which is a top contender for what P&F thought was cold fusion of deuterium. Electron capture is not a strong force reaction like fusion however. It is a weak force reaction.
A little digression about forces. The universe consists of four forces (that we know of):
Gravitational: acts on mass and energy, works at long distances, and is only attractive. Holds planets, stars, and galaxies together.
Electromagnetic: acts on charge (e.g., electrons and protons), works at long distances, and can be attractive or repulsive. Holds atoms and molecules together.
Weak: acts on “flavor” charge (e.g., quarks that make up protons and neutrons can be up, down, strange, charm, top and bottom, not just positive or negative), works only at very short distances, and is neither attractive nor repulsive. Causes radioactive decay.
Strong: acts on “color” charge (e.g., quarks can be red, blue, green, antired, antiblue, and antigreen), works only at very short distances, and attractive and repulsive. Causes atomic nuclei to stay together.
The electron capture theory of the FPE goes back to a pair of researchers, Widom and Larsen, who suggested this as an alternative to the fusion explanation.
Electron capture is when the weak force causes an electron to be pulled into an atomic nucleus, combining an electron with a proton to form a neutron and a neutrino.
Notice that this is clearly a nuclear reaction. In fact, like nuclear fusion, it transmutes Carbon-11, an unstable isotope, into Boron-11, a more stable isotope. Since electron capture involves converting unstable isotopes into stable ones, it naturally involves some kind of release of energy.
In their experiments, the SPAWAR team showed the emission of “soft” X-rays, consistent with electron capture. Electron capture is the reverse of neutron decay, where a neutron decays spontaneously into an electron, proton, and a neutrino.
Their experiments suggest that the deuterium atoms are capturing electrons to convert the proton into a neutron so that two neutrons result in the nucleus. Since two neutrons will not hold together in an atomic nucleus, the nucleus falls apart, creating two free neutrons, some of which are ejected from the lattice.
In addition to neutron production, some experiments would experience a catastrophic runaway thermal reaction, which is consistent with what P&F observed in their lab in Utah. One of the other SPAWAR researchers, Stanislaw Szpak, calculated an energy gain from one such experiment of 10 eV per palladium atom, above the energy of a chemical reaction. This runaway reaction caused substantial damage to the apparatus.
Connecting electron capture to the runaway thermal reaction that P&F and others observed, however, has been far from certain. A larger funded study would be required.
Even if electron capture and transmutation are taking place, it may not explain the excess heat production.
Some studies attempt to look at the problem from an empirical point of view without necessarily explaining the theory. That is, it is more important to be able to reproduce the effect reliably than to understand it. Indeed, in order to gain the support of the larger scientific community, it is essential that practitioners determine the precise requirements to reproduce the FPE.
Storms, for example, suggests that excess power production requires palladium free of large internal cracks and with tight regular metallic lattice of less than 100 microns. Thus, he suggests that the problem with reproducibility is because excess energy cannot be achieved with just any ordinary palladium. Instead, it must be conditioned. He demonstrates this by preparing “activated” palladium by a process that includes heating it to 900 degrees C and slowly cooling it.
Storms further suggests that the reactions only occur in nanocracks one nanometer wide (about the size of a molecule) where the deuterium collects. These cracks, he theorizes, are created by “stress relief” from the heating, while large cracks from high stress actually prevent the reaction. These tiny cracks may be sufficiently small enough to increase the probability of some kind of nuclear reaction.
The palladium to deuterium ratio is most important to achieving a heat reaction but even then it must be repeatedly loaded and unloaded with deuterium to start a reaction. Once the reaction starts, it is fairly reliable for some time. Removing the deuterium stops the reaction but, amazingly, turning off the electric current does not stop it immediately. Instead, it continues to produce excess heat for some time, suggesting that some kind of reaction is continuing.
In conclusion, as with the early attempts to achieve powered flight, we must both understand the mechanics and be able to produce a reliable technology to exploit it for the common good. Even then, there is a lot we don’t know. What is clear is that the work being done is serious scientific work, even if it operates on the fringes of acceptable scientific research.
American Chemical Society. “‘Cold fusion’ rebirth? New evidence for existence of controversial energy source.” Eurekalert. 29 March 2007. Visited: 21 July 2020. https://www.eurekalert.org/pub_releases/2009-03/acs-fr031709.php
Szpak, Stanislaw, Pamela A. Mosier-Boss, and Frank E. Gordon. “Further evidence of nuclear reactions in the Pd/D lattice: emission of charged particles.” Naturwissenschaften 94.6 (2007): 511–514.
Mosier-Boss, Pamela A., et al. “Triple tracks in CR-39 as the result of Pd–D Co-deposition: evidence of energetic neutrons.” Naturwissenschaften 96.1 (2009): 135–142.
Storms, E. K., and T. W. Grimshaw. “Judging the validity of the Fleischmann–Pons effect.” J. Cond. Matter Nucl. Sci 3 (2010): 9–30.
A. Widom and L. Larsen, Eur. Phys. J.C46(2006) 107–117.
Szpak, Stanislaw, and Frank Gordon. “Forcing the Pd/H–H2O System into a Nuclear Active State.” Proc. ICCF. Vol. 17. 2012.
Storms, Edmund. “Anomalous energy produced by PdD, J.” Condensed Matter Nucl. Sci 20 (2016): 81–99.