In 1989 two chemistry professors, Stanley Pons and Martin Fleishman, reported that they had produced cold fusion in an experiment. They electrolysed a solution of sodium deuteroxide in heavy water, using  a palladium anode. During the electrolysis an excess heat and radiation was produced, suggesting a fusion process going on in the palladium anode.

Their report was little exact about the experimental settings, and therefore only few other scientists managed to replicate their findings in the first place. Also the experimental system used was such that they did not have absolute controle of the heat transferes during the process, so there was some doubt about what they actually measured. The findings were therefore dismissed as due to misunderstandings and bad scientific practice, and the matter of cold fusion has since generally been regarded as an area of no value.

However, some scientists did succede in replicating the findings, and quietly a lot of positive research findings from experiments of a lot better quality have been published. The phenomenon is again becoming accepted as a legitimate field of research by steadily more scientists.

The world has an energy crisis, consisting of three main problem complexes. The world has since long been affected by toxic pollutants from use of fossile fuel, and the potential threat of very serious polution from use of conventional nuclear power. These problems are steadily growing.

A problem that may get very great is the heating of the atmosphere and the total environment by the greenhouse gasses produced by fossile fuel burning. This problem gets the most attention nowadays. It is for sure that the greenhouse gasses will change the global environment. It is not for sure yet how dangerous this change will be. It can become a catastophy, it can become partly bad and partly good, and it can be more good than bad. Noone knows for sure how much the earth will be hurt or how much it will gain from the changes that will come. In either case, this is an effect that has to be controlled.

The third problem that will soon become evident, is that the fossile fuels will be used up, so that the earth will go into a lack of energy sources. This may actually happen before the greenhouse effect has done too much damage.

If cold fusion proves to be effective and without dangerous side effects, it can be a good contribution to overcome these problems and controle the greenhouse effect.

By fusion two or more atomic nuclei, protons or neutrons are combined to form a new atomic nucleus. The new nucleus is held together by the strong forces between the heavy particles protons and neutrons. These forces are so strong that they win over the repulsing electromagnetic forces between protons.

However, the strong forces only work at a short distance. Therefore the nucleons (neutrons and protons) must be brought very close together. This is difficult because of the repulsing electromagnetic forces between the protons. In traditional fusion this is achieved by very high pressure and temperature in the fusing material.

The mass a helium nucleus (consisting of two protons and two neutrons) and other light nuclei, are less than the mass of the same number of free protons, neutrons or deuterium nuclei. A deuterium nucleus consists of on proton and one neutron. Heavy water contains deuterium instead of ordinary hydrogen and is therefore designed D2O. When fusion occurs, this mass difference cannot be lost. It is converted to kinetic energy and gamma radiation. Therefore fusion of protons, neutrons or kernels of the very lightest elements into heavier elements is a very potent energy source.

One has not yet been able to make a controlled  high temperature fusion process that yields more energy than the energy put in. The only practical device by which one has managed to exploit the energy from warm fusion, is the hydrogen bomb.

There is no fully developed model for cold fusion yet. The hypothesis behind the phenomenon is however very simple: All particles behave according to quantum mechanical laws. These laws say that the coordinates and energy state of a particle at one point in time determine the probability of finding a particle a place with some given coordinates at another point of time, but the exact place cannot be predicted. Actually, a particle can be found anywhere at that other time point, put all places do not have the same probability. Some places are very probable, and others are very improbable. Because of this, even a particle that is not in any net motion nevertheless will shift place randomly to some extend, usually very little, but sometimes more.

By bringing particles and nuclei very near each other by using some force, this will happen: The quantum mechanical behaviour will as always make the particles shift their position more or less all the time, and sometimes they get near enough to let the strong nuclear forces to take action and make them fuse.

The standard theory tells that this cannot happen in such an amount to be detected. Still it does. Either the standard theory is not complete, or one has not learned to use the theory in a right fashion. The mathematical apparatus of the theory is so complicated, that it is impossible to predict what can happen and what cannot happen with a short glance at the equations.

Cold fusion must also contain other reactions than warm fusion. It is difficult to produce fusion of other things than one deuterium and one tritium kernel by warm fusion. By cold fusion, two deuterium kernels easily fuse, and even fusion involving hydrogen kernels (free protons) have been reported. Neutron and gamma radiation has neither be reported to that extend predicted by the standard understanding.

This is also true about important known warm fusion processes. The heat from the sun is produced by fusion. But the sun does not either radiate according to the standard understanding. So the standard understanding must be inomplete one way or another.

The original experimental system exerted by Pons and Fleischmann consisted of these elements: A palladium cathode, a nickel anode and a solution of sodium deuteride NaOD (20%) in heavy water D2O. Sodium deuteride is sodium hydroxide with heavy hydrogen (deuterium) in the -OH ion, and therefore designed as OD-.

When electricity was applied to this electrolytic system, deuterium atoms were produced at the cathode, and oxygen at the anode. The deuterum atoms went into the palladium crystal lattice in great extend before combining to D2.

Excess heat was then produced in the electrolytic cell, apart from the electrolytic heat. Helium, tritium and neutrons were also produced, but the latter two products not in the amounts that would have been produced in a hot fusion. Therefore the fusion reactions in the system are different form those in hot fusion, and probably more complicated.

It is difficult to fuse two helium atoms in standard fusion, and when it occurs, the product is usually one tritium atom and one proton.

Not many scientists managed to reproduce the results in the first place, because of unclear documentation from the originators about the conditions set up and used during the experiment. Still some of them succeeded, and gradually the conditions for a successful fusion process have been established. The best fusion occurs when the palladium is somewhat over-saturated, that is when there are nearly as many atoms of deuterium as those of palladium in the crystal. The saturation is controlled by the voltage applied and the speed of the electrolysis.

However, the process seems to be susceptible for tiny variations of parameters, also parameters not yet known. For some reason some palladium electrodes simply will not work, and one is not aware of ecsactly which are the disturbing variations.

The electrolysis in itself is only a means to put deuterium into the palladium crystal matrix, and has nothing to do with the fusion itself. The electrolysis produces separate deuterium atoms in the first place, and those go easily into the crystal matrix before they combine to deuterium atoms.

As seen, cold fusion can be started and maintained when one packs a huge quantity of deuterium kernels into inter-atomic spaces in a crystal lattice. In order to start a fusion process, the density must apparently be the same as in liquid pure deuterium. Since there is no fusion process in liquid deuterium, the crystal lattices probably packs the deuterium kernels together in tight sub-microscopic groups much more dense than the average density in the lattice, and thus facilitating quantum mechanical tunnelling between the kernels in these dense groups.

A great variety of systems showing cold fusion has been discovered in the last years. Most of these use some kind of crystal lattice.

- Fusion seems to occur by electrolysis of a solution of KCL/LiCL/Lid using a palladium anode, but many attempts of result reproduction have failed.

- Cold fusion has been reported in experiments where various metals are bombarded with D+ - ions.

- By applying pressurized deuterium gas upon finely divided palladium, signs of fusion have been produced, and replicated by other scientists.

- By electrical discharge between palladium electrodes in a deuterium gas, signs of fusion have been seen. By such a discharge, plasma consisting of D+ ions and electrons will be formed between the electrodes. The D+ ions will be attracted to the surface of the negative electrode, and a high density of D+ will occur at this surface. Since also these D+ -ions will have a high thermic energy; many of them will be thrown very near each other. Quantum-mechanical tunnelling can then do the rest of the approaching process, so that fusion can take place.

- By reaction of Ni with H2, replicated results showing signs of fusion have been produced. Even though H2, and not D2 has been used, the reaction has still has been reported to take place. This suggests a very different reaction mechanism than that of warm fusion. Some scientists speculate that hydrogen atoms can exist in quantum states where the electron and proton are so near each other that the atom reacts lika a neutron.

When gas bubbles in a liquid are exposed to  ultrasonic waves that transfere energy to the bobbles, the bobbles can be brought into a state where they rapidly and periodically  expand and collapse, syncronized by the sound waves.

Such oscillating bobbles can send out light by certain frequencies of expansions and collapses, and provided the gas is composed in a suited way. Just at the end of each collapse, the spot temperature in the bobble can reach as much as 10 mill degrees, even though the average temperature in the total blending is only a few hundred degrees at most.

When deuterium is a component in the oscillating bobbles, fusion has been observed. This fusion is strictly not cold fusion, but a kind of hot fusion, and the process sends out neutrons, gamma-rays and tritium atoms as predicted by standard understanding.

The process has not yet produced an energy output greater that the input by the ultrasound. The phenomenon  is confirmed by independent investigators.

Cold fusion in crystal lattices has been prooved to produce a net energy output. Experimental 1 MW or more experimental reactors has been set up and demonstrated.

Ecperimental reactors has been developed, but no one has yet made a reactor that works stably enough to be of commersial use.

Even though cold fusion do not produce the amout of radioactive and toxic vaste that fision reactors do, they produce some degree of radiation. There may also be a potential for an uncontrolled process leading to  overheating and explotions. Therefore there are potential  security issues that must either be dismissed as non existant or solved technically.

Commercial household heaters seem to be the first type of reactors some companies try to develop. The hope of the companies is that these will make a way for greater reactors and uses in the market.

By now noone knows how successful cold fusion will be in the energy market. Cold fusion can make a revolution that gives the world cheap clean energy in enormous quantities, but it is too early to predict.