I believe we're getting to the point where, if we regress below the level of viable industry capable of running any of our high-tech energy sources (whether it'

I believe we're getting to the point where, if we regress below the level of viable industry capable of running any of our high-tech energy sources (whether it's oil, coal, nuclear or any of the renewables), then we aren't getting it back ever - nor will any future civilisation, because without huge geological shifts all the sources will be beyond reach of primitive tech...