I guess if the price of BTC goes up, then it makes it more "worth it" to throw more energy at mounting a double-spend attack, and therefore the energy needed to protect the network against such an attack also goes up?
Close, but not correct. As the price of BTC goes up, so does the expected reward for mining any given block, making it profitable to spend more electricity in pursuit of the rewards. This results in a net increase in electricity usage as everyone spends more in an attempt to capture the rising value of mining a block successfully.
In practice each miner is incentivized to spend an equal amount in electricity per block (at local rates) as the expected reward per block will net them. This results in a 51% attack being inordinately expensive, which was the point of the original design.
And thereby offsetting other inelastic demand for electricity, forcing them to count on non-renewables instead.
Bitcoin might be renewable if every single miner pinky swears to turn their rigs off the moment renewables stop over-producing, but come on, nobody believes that'll happen.
> Despite what the born-again eco-warriors have to say about consumption and the environment, Bitcoin can actually be an incentive for safe energy sources.
Interesting you've got to put an ad hominem in there about people who care about the environment. Probably not a good sign for the second half of this sentence, and it makes me wonder if you're representing other's positions in good faith.
Also, oops: https://e360.yale.edu/digest/bitcoin-miners-resurrect-fossil...
Sure, bitcoin miners will use cheap renewables if they're available. They'll also happily use whatever the hell is available too given the opportunity, since they need to use so much of the stuff. They're particularly notorious for driving up electricity rates locally as they turn previously abundant renewable hydro energy into a over-subscribed resource, requiring towns to import electricity from, yes, fossil fuel plants.
If 1 coin costs $50,000, and you already own the rig, it's worth spending $49,999 on electricity to mine the next coin and you will make a profit. If you're rig can't do that, you're better off just turning it off.