It might be possible to use a stream of coherent electrons generated from a Bose-Einstein fluid and a very powerful laser to transform the mass of the electrons into energy.
It seems that electron-positron pairs have been generated from two very high energy photons. If you had two extremely powerful gamma ray lasers, you should be able to generate a coherent stream of electron-positron pairs. Of course we don't have that kind of laser, and are not likely to get one soon.
But it might be possible to use a laser beam of less energy to change an electron into a positron. Then when the positrons combined with the electrons in a target, high energy photons would be released, and an electric current would be generated, if the target was conductive.
Here's the conjecture.
We assume that particles are really just photons trapped in a standing wave. Like a sound wave resonating in a closed chamber, the gamma level photons that constitute the electron resonate in some kind of resonance chamber. That would be why particles behave like waves. Particles are trapped waves.
That would mean that when two particles collide the results of their collusion would depend on the exact phase relationship of all the photons involved. Identical particles could collide at different times with the exact same velocity vectors, but the results would be different. Also, identical particles with identical phase relationships between the photons involved would produce identical results.
The fact that interference patterns from atoms generated from a Bose-Einstein fluid are stable would seem to mean that all the particles in a Bose-Einstein fluid have their phase relationships synchronized.
So if we could determine what the exact photonic makeup of an electron and a positron, we might then be able to design a laser that would generate the photons that have the right frequency, power, and phase to convert an electron into a positron using a coherent beam of electrons and one or more laser beams. I believe the electron and the positron have the same mass, so any transaction that began with one and ended with the other should have zero energy cost.
If we have a resonance mechanism for the election-positron energy level, we might also have one for the neutron energy level. The standard theory would suggest one for the neutrino level and also the Higgs level.
It is interesting to note that neutrinos have very low mass which means they have low energy, even when traveling at really high speeds. It should be possible to make neutrinos from much lower energy photons. My understanding of current theory is that neutrinos have mass, but it has not yet be successfully measured, so we aren't sure of how much energy it would take to make one.
Another difficulty is that neutrinos are terribly hard to detect. But we might be able to detect the disappearance of the photons used to make the neutrinos.