antimatter

That is what antimatter can do. Annihilating a kilogram of
antimatter will give out about ten billion times the amount of
energy released when a kilogram of TNT explodes.

Under suitable circumstances a
proton can change into a neutron and emit energy some of which
materializes as a positron, similar to what happens in the positron
emitters of earthly medicine.
The positron finds itself in the heart of the sun, where there are
lots of electrons, and is instantly destroyed, turned into gamma
rays. These try to rush away at the speed of light but are interrupted
by the crowd of electrically charged particles, electrons,
and protons that form the seething star. Buffeted this way and
that, repeatedly absorbed by electrons and then emitted with less
energy than before, it will take a hundred thousand years before
gamma rays manage to reach the surface, hundreds of thousands
of kilometres above. In doing so the rays lose lots of energy, their
character changing from X-rays to ultra-violet and at last into the
rainbow of colours that are visible to our eyes. So daylight is the
result of antimatter being produced in the heart of the sun and, in
part, of its annihilation.

This is not just a story of antimatter in history; the fusion
processes that power the sun are producing positrons as you read
this, and they are being annihilated faster than you can reach the
end of this sentence. The gamma rays that were made just now
are already wending their way upwards, eventually to emerge and
illuminate the earth a thousand centuries from now.

Paul Dirac, Carl Anderson, and Robert Millikan, the principal players in the first act of the antimatter saga,

The laws of electricity and magnetism that underlie the existence
of bulk matter don’t care which bits of matter carry negative
charge, and which bits are positive. If we swapped all positives
to negative, and all negatives to positive in some situation, the
resulting forces would be the same and the structures they built
would also be unchanged.

The Principles of Quantum Mechanics by the Cambridge mathematician, Paul Dirac

The Dirac Code

The electrons in all atoms are identical. The difference between
one variety of atomic element and another is the number of electrons
orbiting the central nucleus (and of course the number of
protons in that nucleus).

If we found large quantities of antimatter where nature had
already expended energy in making the stuff so that we could
now make use of it, our fuel problems might indeed be solved.
But so long as we have to make it ourselves, we can do no better
than making storage batteries, which produce less than it takes
to make them in the first place. Regrettably antimatter is not a
panacea for ‘saving the planet’. Thankfully, neither is it ‘the most
deadly weapon’.