He started by noting that what we call Renewable Energies today are in fact non-renewable systems capturing renewable energy.

This is a very interesting point and one which the proponents of wind rigerously deny. A few years back I asked the BWEA for some energy payback calculations for wind energy, and they sent me a paper written, I think by David Milborrow. I was at the time optimistic towards wind power, and to some extent I still believe it may be our "best chance renewable", certainly in the UK.

On face value an energy payback of 30:1 is clearly possible, which makes wind totally sustainable. After a few years attempting to digest our energy dilema, I have thought longer and harder about whether we really understand the total energy subsidy given by fossil fuels.

The calculations for wind energy pay back were based on the specific energy consumtion per unit weight of products of the various industries involved in both materials and components.

Did it include all the fuel used for the workers driving to factories to make the components? I never found out.
Did it assume Epoxy resin was made from oil or the electricity from the turbine via chemical synthesis? I never found out but the difference in energy input must be significant.
Does it include the energy required to make the infrastructure to support these devices?

My only conclusion is no one really knows and will will find out the hard way.

Fossil fuels, regardless of EROEI, have currently been available and able to supply nett energy at a rate we have required it. This is equivalent to an "Infinite Busbar". Once the energy system cannot meet demand, the word infinite has to be removed and replaced by "finite" ! Wind turbines are a finite busbar until you have installed more capacity than you require for your nett energy requirements.