<sigh>

Gav, Please read again very carefully what I wrote.

This is not an either-or issue, we both acknowledge that.

However, in any fair argumentation, the proof of burden is on the one making the claim. I did not see a single shred of proof from John15. I did provide latest EIA AEO 2008 assessment for coal use growth up to 2050.

And you are right that the only calculation that I can refer to is the only publicly available high level calculation in the world that I know of, that of Hirsch et al.

I never claim it cannot be done (100% certainty).

I'm claiming the scale issue is very, very large and the time available for completion appears to be very short based on oil depletion forecasts.

My main point is the obvious thing that claiming it is theoretically possible does not make it so.

Theoretical possibilities are not realities until built.

However, having studied energy companies locally, I can attest that the average 5 year permit process, 2-3 year financing process, 7-10 year build time and the 10-25 year depreciation time does not make things easier. Especially when the industry is made ever more so confusing by constantly changing political winds and legislation, the volatility in the CO2 emission trading market and primary fuel markets (gas, coal, oil).

Please do not mistake me for a dichotomic doomer, because I'm not one.

Now, I've provided one very big study reference in this post.

Let's see if John15 can post one that backs his claims. One that is based on physical/financial high level calculations - not just lab-tech breakthroughs about algae and back of the envelope musings about how cheap pv is going to be in 2020.

Just saying 'it can be done' is as silly as if I had said 'it can't be done' (which I didn't write, if you read carefully again what I wrote).

*PS as for real-world solution: I am consulting both energy companies and politicians locally on this. That's what I mean when I say mere assertions get very little done.