
The importance of such a result would be colossal. Being able to generate more energy than you input would be our golden ticket to unleash energy sustainability. The end of energy scarcity as we know it. With abundant energy on tap we’re talking about global clean drinking water, emission free energy resources, electricity for all of humanity and interstellar travel…
So why has so little progress been made since the Fleischmann-Pons experiments in 1989? In truth, many attempts have since been made to repeat the experiments but, unfortunately for us all, no one has succeeded in making cold fusion work. Ever since 1989, there has been a heated debate among scientists, mostly consisting of a swathe of scathing reports against Fleischmann and Pons and their methods. Countless scientific bodies, institutes, research councils, research journals and even government agencies all weighed in on the issue. Suffice it to say, that although the claim of cold fusion was an extremely hard pill to swallow, at the end of the day it didn’t in fact meet the expected verification criteria of any new found technology; especially something as groundbreaking as cold fusion. And so, for years, cold-fusion has been relegated to the dustbin of science history.
Any mention of cold fusion, has since met with heightened skepticism and a fear of academic suicide. Which makes the new publication on cold fusion, in the journal Nature, all the more remarkable. Motivated by “the possibility that such judgement might have been premature”, they “embarked on a multi-institution programme to re-evaluate cold fusion to a high standard of scientific rigour”. Although their final results are essentially null, it highlights a key component to scientific discovery: don’t be too quick to disqualify new ideas, since you don’t know where they might lead. Although the results of the Nature paper didn’t give us cold fusion, they propose a number of exciting areas of research, derived from their work, that could very well have a high impact in other areas of research, like materials science. But in 1989, in the wake of these experiments, the case went cold…
What was the cold fusion that Fleischmann and Pons tried to achieve? Here is a very brief introduction of what ‘hot fusion’ (or just… ‘fusion’) is, to drive the point home about why cold-fusion would be so remarkable:
Fusion is a nuclear reaction whereby two small nuclei fuse, forming a larger nucleus. The initial nuclei are often positively charged, strongly repelling each other. However, when those nuclei are close enough, electrostatic repulsion gets overcome by the attracting 'strong nuclear force', which causes those nuclei to fuse together. This releases a huge amount of energy. But bringing nuclei together (especially two positively charged ones) is by no means a simple task. It does occur in our Sun constantly: hydrogen fuses to form heavier elements, releasing light and heat. However, the processes governing fusion of elements in the Sun are driven by the large amounts of pressure and heat causing those nuclei to fuse. Attempts to replicate hot-fusion, on Earth, are normally done by accelerating a magnetically confined plasma (e.g. Tokamak *) or with electromagnetic heating or particle beams, and more. Unfortunately, it requires so much energy to bring about fusion in these Earth-based instruments that it far exceeds the energy released by the fusion reaction itself! Only once the energy output is greater than the energy input, can we really start talking about the usefulness of fusion energy.
Enter… cold fusion. Cold fusion claims to release a measurable amount of energy without having to heat your nuclei to extremely high temperatures and pressures. The original experiments in 1989 attempted to dissolve a high concentration of deuterium (which is a hydrogen atom (i.e. a proton) packed with an extra neutron) in to a palladium electrode. The concentration being so high, that hydrogen nuclei within the solid lattice actually come energetically closer to one another than in a lattice of solid hydrogen; assisted by counterbalancing of charges from electrons as well. Fleischmann and Pons used this idea in an electrolytic cell, and found that their electrical power output was greater than their electrical power input. This purportedly meant that they had liberated some energy by fusing hydrogen. Eureka! Not so fast...
Unfortunately, after ~3 decades of research, cold fusion claims have not materialised. The research published in 2019 in the journal Nature, however, does offers a promising perspective on ancillary issues surrounding some aspects of cold fusion. For example, loading palladium with an ‘ultra-high’ saturation of hydrogen has exhibited unique materials properties, such as phase changes in these materials. At certain hydrogen concentrations, these highly saturated materials behave in unique ways and respond differently at particular pressures and temperatures. Pushing the limit of these material properties is certainly a worthwhile endeavour, especially since they exhibit distinct, measurable characteristics that can be controlled, manipulated and predicted. Indeed, loading metals with extremely high concentrations of hydrogen may very well be a prerequisite for cold fusion but pushing the limit of hydrogen saturation may also be a promising direction to explore, in and of itself **. Simply put: no one has been able to convincingly show that such metal loading (with hydrogen) is even possible, let alone it being a precondition for the elusive ‘cold fusion’.
Lets not get bogged down with cold fusion though. The truth is that this study in Nature was very brave; it touched a nerve and dared to re-think old scientific ideas and perhaps most importantly, did not overstate their claims about cold fusion at all. They give a very pragmatic outlook and prospect for the future, touching upon many important areas that could really benefit from further scientific exploration; and we may just learn something as a bonus along the way.
One question that was put to the authors was: ‘why pursue cold fusion when it has not been proven to exist?’. The authors respond by saying: “one response is that evaluating cold fusion led our programme to study materials and phenomena that we otherwise might not have considered. We set out looking for cold fusion, and instead benefited contemporary research topics in unexpected ways.”
Or in the words of a modern proverb: “Shoot for the moon, even if you miss it, you’ll land among the stars.” - Norman Vincent Peale, i.e. shoot for cold fusion and who knows what you might discover...
* a few UK based Tokamak's are of note: Oxford's Tokamak Energy and a the JET partnership
** the Nature paper provides a few more exciting secondary outcomes that may also derive from cold fusion research