cold fusion claims resurface

Looks like cold fusion is one of those great lies that will never be truly put to rest. Two individual researchers, Andrea Rossi and Sergio Focardi, have announced that they have the ability to fuse hydrogen and nickel into copper, and are able to use 400 W of input heat in a room-temperature reactor to generate 12,400 W of output heat as steam, for a 31x return on energy (possibly 8x in commercial applications). Furthermore, they generate no radioactive waste products. Is this really possible? In a word, no.

1. It is basically impossible to get room-temperature nuclei to fuse at an appreciable rate. That is because of the electrostatic repulsion between two positively charged nuclei: a phenomenon known as the Coulomb barrier. The repulsive energy is proportional to the product of the charge of the two nuclei. That means that fusion between hydrogen and nickel is much less likely than between two hydrogen atoms. Empirically, it has been observed that hot fusion reactors such as the sun tend to favor the fusion of light elements, such as hydrogen, carbon, nitrogen, and oxygen. Usually heavier elements are produced primarily by very large and hot stars, at hundreds of millions of degrees kelvin.

2. The nuclear reaction they propose is wholly inconsistent with their claimed observations. The primary naturally occurring isotopes of nickel are nickel-58 (68.3%) and nickel-60 (26.1%), while the primary naturally occurring isotopes of copper are copper-63 (69.2%) and copper-65 (30.8%). However, if you fuse a single proton with nickel, you should produce primarily copper-59 and copper-61, as well as gamma rays. Both resultant nuclei are highly radioactive, with half-lives of 117 seconds and 3.33 hours, respectively, with correspondingly high specific activities. They decay via electron capture and possibly beta+ decay (depending on the relative energies of the two nuclei), thus emitting neutrinos and possibly positrons (anti-matter). Furthermore, the daughter nucleus, nickel-59, is also radioactive over a much longer time scale, with a half-life of 110,000 years. In short, if their reaction works as claimed, they should be producing highly dangerous gamma rays (some possibly produced around 511 keV via intermediate positron-electron annihilation), as well as leaving a highly toxic nuclear waste pile behind.

3. Although it doesn't prove anything directly, it's suspicious that the researchers seem extraordinarily eager to circumvent the standard peer review process. Since they failed to publish in a normal peer-reviewed journal, they instead created their own online journal to serve as a vehicle for disseminating their results. And the information they provide in their own journal paper is very vague: they never give all the details of how their reactor is set up, and never quantify the nature of the copper products that were allegedly observed.

4. There are a number of potential alternative explanations for their results that don't require rewriting the laws of physics, such as the possibility they are engaging in standard chemistry. As I first saw pointed out on slashdot.org by number6x, if the electrodes have oxidized nickel on the surface, they can be reduced by hydrogen gas in an exothermic chemical reaction that yields elemental nickel and steam. The presence of copper can be explained by noting that it may have been present all along (nickel and copper commonly are found together in mines). This implies that the authors have essentially discovered a somewhat dull battery chemistry.