however in the world of cryotocurency, this competition for processing power has led to excessive increases in GPU prices as well as high energy requirements limiting already inefficient power supplies. Although most of China's miners use surplus hydroelectricity, people in countries like Iran and the US depend on fossil fuels for mining.

So if you have a coin that has a high market cap (lots of people mining it because it's profitable), guaranteed with a lot of energy, and nothing to use for transactions (low traffic), then we have a situation on which network is too secure, miners are mining empty block and all this power is wasted. The greenest POW projects are those where all blocks are filled to the limit all the time (ETH, BTC) maybe as well (SOL, BNB)