Climate collapse demands a supply of energy that is far cheaper than fossil fuels, resistant to bad weather and natural disaster, and sustainable in fuel inputs and pollution outputs. Can a new poorly understood technology from a stigmatized field fulfil the need? The Low Energy Nuclear Reaction (LENR) could help at large scale very quickly.
In 1989 Pons and Fleischmann provided an initial glimpse of an unexpected and poorly understood reaction dubbed "cold fusion," which makes lots of heat and very little radiation.
LENR is being pursued quietly by many large aerospace companies, leading automakers, startup companies and to a lesser extent, national labs.
Over the years many teams have observed the reaction by various means, and a consistent, though unexpected, pattern has emerged. Experiments have become more repeatable, more diverse, more unambiguous, and higher in energy.
There are no expensive or toxic materials or processing steps, so it could be the step beyond fossil fuels we have been waiting for. No government regulated materials are used, so a quick path to commercialization is possible.
Familiarity with hot fusion led to initial false expectations. Early very hasty replication work at MIT was declared a failure when heat but no high energy neutrons were detected. The reaction requirements were not known at first and many attempts failed to reach fuel loading and ignition energy requirements. Even when the basic requirements were met, nano-scale features varied in materials and made the reaction hard to reproduce. Pons & Fleischmann had trouble repeating their own excess energy results after they used up their initial lucky batch of palladium. Today we understand better how material defects create required high energy levels.
In many experiments with LENR, observed excess heat drastically exceeds known or feasible chemical reactions. Experiments have gone from milliwatts to hundreds of watts. Ash products have been identified and quantitatively compared to energy output. High energy radiation has been observed, and is entirely different than hot fusion.
Dr. McKubre at SRI International teased out the required conditions out of the historical data. To bring forth LENR reactions that produce over-unity energy, a metal lattice heavily loaded with Hydrogen isotopes, driven far out of equilibrium by some excitation system involving proton flux and probably electromigration of lattice atoms as well.
A great quantitative characterization of the outputs was Dr. Miles' meticulous 1995 experiment at China Lake. LENR releases Helium-4 and heat in the same proportion as familiar hot fusion, but neutron emissions and gamma rays at least 6 orders of magnitude less than expected.
Successful excitation systems included heat, pressure, dual lasers, high currents and overlapping shock waves. Materials have been treated to create and manipulate flaws, holes, defects, cracks, and impurities, increase surface area, and provide high flux of protons and electron current. Solid transition metals host the reaction, including Nickel and Palladium.
Ash includes ample evidence of metal isotopes in the reactor that have gained mass as if from neutron accumulation, as well as enhanced deuterium and tritium. Tritium is observed in varying concentrations. Weak X-rays are observed along with tracks from other nuclear particles.
LENR looks like fusion judging as a chemist might, by the inputs Hydrogen and output Helium-4 and transmutation products. It looks not-at-all like fusion when judging it as a plasma physicist might—by tell-tale radioactive signatures.
Converting Hydrogen to Helium will release lots of energy no matter how it is done. LENR is not zero-point energy or perpetual motion. The question is whether that energy can be released with affordable tools.
Plasma physicists understand hot thermonuclear fusion in great detail. Plasma interactions involve few moving parts, and the environment is random so it's effect is zeroed out. In contrast, modeling the LENR mechanism will involve solid-state quantum mechanics in a system of a million parts, being driven far out of equilibrium. In LENR a nano-scale particle accelerator can't be left out of the model. A theory for LENR will rely on intellectual tools that illuminate x-ray lasers or high temperature superconductors or semiconductors.
Many things need to be cleared up. How is the energy level concentrated enough to initiate a nuclear reaction? What is the mechanism? How do output energies in the MeV range come out as obvious high energy particles? Dr. Peter Hagelstein at MIT has been working hard at a "Lossy Spin Boson Model" for many years to cover some of these gaps.
Robert Godes at Brillouin Energy suggests a theory that matches observations and suggests an implementation. The "Controlled Electron Capture Reaction." Protons in a metal matrix are trapped to a fraction of an Angstrom under heat and pressure. A proton can capture an electron and become an ultra-cold neutron that remains stationary, but without the charge. That allows another proton to tunnel in and join it, creating heavier Hydrogen and heat. That creates deuterium which goes to tritium to Hydrogen-4. Hydrogen-4 is new to science and is predicted (and observed?) to beta decay to Helium-4 in about 30 milliseconds. All this yielding about 27 meV in total per atom of Helium-4, as heat.
The proton-electron capture reaction is common in the sun, and predicted by super-computer simulation at PNNL. It is the reverse of free-neutron beta decay. Such a reaction is highly endothermic- absorbing 780 keV from the immediate surroundings.
Fission experts expect hot neutrons to break fissile atoms up. LENR does it backwards—ultra cold neutrons (which cannot be detected by neutron detectors, but can readily be confirmed by isotope changes) are targets for Hydrogen.
Hence Helium is produced with the tools of chemistry and without overcoming the Coulomb positive-particle repulsion force. And without requiring or producing radioactive elements.
It is strange that LENR is neglected by the DOE, industry and the Pentagon. But no stranger than the history of nuclear power—if it weren't for the leadership Admiral Rickover, and his personal friends in Congress, nuclear fission power for submarines and power plants would never have seen the light of day. The best endowed institutions rarely disrupt the status-quo.
Progress is being made quickly by private enterprise in lieu of government support. Sadly that means you cannot stay up to date relying on a subscription to "Science." But stay tuned.