People fall off rooftops fitting solar panels, burn to death repairing wind turbines that they can't climb down fast enough to escape, and dams burst and wash away towns. Renewable energy is much less killy than fossil fuels, but per megawatt hour, it's comparable to nuclear, despite a few large incidents killing quite a lot of people each. At the moment, over their history, hydro is four times deadlier than nuclear, wind's a little worse than nuclear, and solar's a little better. Fission power is actually really safe.
The article's talking about fusion power, though. Fission reactions are dangerous because if you've got enough fuel to get a reaction at all, you've got enough fuel to get a bigger reaction than you want, so you have to control it carefully to avoid making it too hot, which would cause the steam in the reactor to burst out and carry chunks of partially-used fuel with it, which are very deadly. That problem doesn't exist with fusion. It's so hard to make the reaction happen in the first place that any problem just makes the reaction stop immediately. If you somehow blew a hole in the side of the reactor, you'd just get some very hot hydrogen and very hot helium, which would be harmless in a few minutes once they'd cooled down. It's impossible for fusion power, once it's working, not to be the safest way to generate energy in history because it inherently avoids the big problems with what is already one of the safest ways.
Ethereum's been proof-of-stake rather than proof-of-work for couple of years now, so it's no longer energy intensive.
There inherently can't be a way to make proof of work lies wasteful as long as there are people who want to do the work. If you make hardware more, then it makes it cheaper to do the same amount of work, so people buy more hardware and do more work and more power gets used. If you make hardware less efficient, people just use the old hardware. You have to abandon proof of work altogether and switch it to something else that isn't inherently tied to energy usage.