I should have been more specific — I was referring to the more efficient thermoelectric devices discussed in the article. Rather than powering a radio from an oil lamp, I wanted to power electric lights, a radio, etc. from the wood stove. The older tech just wasn’t cost-effective.
Not efficient enough, even the new ones aren’t efficient enough to do what you want.
Google powerchips plc. It’s probably vapor ware but uses an entirely different technology with the potential to be nearly an order of magnitude more efficient.
Every now and then they announce an advancement towards production but I’ve watching them for years and it’s still more theory than product.