Zorgon -- I have nothing against solar as an intermediate alternate power source. But solar is intended to produce electricity to run current-design electrical devices. If electromagnetic flux on this planet leads to all current-design electrical devices going kaput, then this kind of solar is dead-ended. I'm trying to think beyond that dead-end.
MMe M -- The military does have, I'm pretty sure, just about all the alternative tech we could use here. Whether we'll ever get it is the question. In the meantime, I kind of like the glow worm excrement idea, but we don't have those larvae here in North America, at least not where I live. But maybe a lightning bug farm idea could be developed. As kids we caught them in a jar, but they didn't live very long, and they are seasonal to the summer mating season, so that would require some exploration.
Baggywrinkle -- Tesla was working on the "stick in the ground" universal energy field, free energy, back in the 1920s and all that happened was the military stopped him and used whatever they could of his ideas as weapons. All those alternative-energy people who have been killed in the past 60 years also had free or near-free energy inventions. Maybe some of this will emerge after everything collapses.
Also, remember Leedskallen? The guy who built the "coral castle" in Florida without any kind of machinery except a wooden tower of some kind, lifting enormously heavy blocks of coral by himself, without helpers? He said he had rediscovered the secret of how the pyramids were built, and refused to share any of his research with the military when they approached him. So they didn't get it, but unless somebody can rediscover what he rediscovered (and he did it through research at public libraries!), this secret is lost once again!