This is an interesting research question.

If we start from the basics and try to estimate how much non renewable feed (fossil fuel or nuclear) can generate a 1mw renewable facility (e.g a solar, wind, hydro, bio gas digester and biomass) and we estimate what's the global energy demand is.

There is a chance of getting a rough guestimate.

To me the answer is

1. More non-renewable energy resources than the renewable energy resource the renewable energy technology can create.

2. More fossil fuel emissions than the emissions renewable energy technology can save.

Agree with Chibuzor Azodo

It should be zero - that is, you ought to be able to build all the renewable energy converters you need using only renewable energy. Nature does this - there is arguably no external input required for plants to grow, solar energy supplies everything. The only proviso is the existence of the planet's hydrological cycle that supplies fresh water to the land for plants to grow - but this equally supplies fresh water for any artificial renewable energy conversion processes.

Interesting discussion

More than 50 years, as not o ly development of res is neefed, but also the invested co2 must be covered by res

I studied this issue and proposed a road map based on the rate of prodcution of the renewable energy at this time and the prediction of the future development of the renewable energy specially the photo voltaic electricity generation. I would like that you comment on my proposed road map it is like the Moore law for the evolution of the integrated circuit:Method From conventional to renewable energy transformation challenge

Best wishes

Waiting your response!

Dear Massimo De Angelis Abdelhalim Zekry Tony Maine Ioana Ionel

As per my observation, Its genuine talk of this disruptive era, whole world is in the race of solving important issues by creating alternative issues to justify the law of the land. Alternative Innovation became more popular than innovation for betterment and sustainability(Env).

To answer this question: Whole world is trying hard to reduce carbon footprints. Rather than saying how much non-renewable energy required to produce renewable energy. It would be more practical to say How much green source and mechanism required for renewable technology sufficient to generate most of today's global energy usage. Rest may be managed through non-renewable energy based renewable energy technology.

Based on study, I guess by 2030: 55%(non-renewable energy based) - 45% (green source based).

I agree with @Chibuzor Azodo and @Mohamed Azab

A lot. First we need to interconnect all the energy systems of the world, only then we could try to generate 100% renewable, since renewable energy sources are not spread equally around the globe, and only one form of clean energy will newer generate 100% of energy needed.

I agree completely with Prof.Abdelhalim Zekry