> Each of those uses significantly more energy than Bitcoin. These discussions should talk about the ratio between a certain measure of productivity (e.g. GDP

> Each of those uses significantly more energy than Bitcoin. These discussions should talk about the ratio between a certain measure of productivity (e.g. GDP generated for the country) to the energy use; energy on its own does not mean much. I'm sure worldwide food production consumes more energy than Bitcoin. Other than that, a problem with POW (at least as implemented in Bitcoin) is that technological advances won't result in less energy consumption as it's mostly a function of (price of Bitcoin, price of energy).