... which is to say, unless the energy supply, material supply, and waste disposal/recycling are all sustainable, the economy in question is not sustainable.

Te fact that there is sufficient sustainable energy supply to provide a sufficient energy budget to sustain an industrial economy does not imply that there is a sufficient sustainable energy supply to supply ongoing, unlimited exponential growth in energy consumption per capita.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.