[ben_w]

> coal accounts for more than 75% of the annual power supply and benefits from favourable government tariffs.

That's a choice, not a need.

The need is right by that:

> solar panels only need to operate for 4-8 months to offset their manufacturing emissions.

> We're talking billions of tonnes of raw materials here to meet decadal global demands, and it simply isn't just sand (and remember that really good sand is a resource in demand also):

1) Doing nothing leads to burning around 8 billion tons of coal per year just by itself.

PV, even when made from coal power, reduces that by a factor of 40-90.

And, as you do make and connect it, the fraction of power coming from coal constantly decreases anyway.

2) I said "main component by mass", not "just". My point stands.

3) You don't need "good quality" sand for PV. Crush some rocks if you like, silicates are everywhere.

[defrost]

> 1) Doing nothing leads to burning around 8 billion tons of coal per year just by itself.

Who's advocating doing nothing, is that something I said?

2) I said "main component by mass", not "just". My point stands.

You clearly stated "Zero". That's incorrect. The energy demands of mining are not insignificant by any means.

There are large amounts of material being mined, both sand, and silver, and others to support PV

3) You don't need "good quality" sand for PV. Crush some rocks if you like, silicates are everywhere.

You've not ever mined anything or worked in geology, have you?

[ben_w]

> Who's advocating doing nothing, is that something I said?

I mixed you up with the other poster, but your comment and theirs together very much pattern-matches to such a position, yes.

> You clearly stated "Zero". That's incorrect. The energy demands of mining are not insignificant by any means.

I said zero in the context of "how much coal and how many mountain tops are needed".

This remains correct.

Zero mountains need to be levelled, zero coal needs to be used.

And what do you mean by "insignificant"? Your own citation is saying 4-8 months to repay their own energy cost, for devices which last 25-30 years. I think 1.1-2.6% of their lifetime output counts as "insignificant" in proportional terms, even though that's a big number when you multiply 2 TW by 30 years to find out what it takes to scale to the current global electricity demand.

> You've not ever mined anything or worked in geology, have you?

Have you?

Silicon is the second most abundant element in earth's crust after oxygen.

The doping agents are less common, but also you need far less of them.

Again, no mountains need apply — even for the single most important element, the scale needed is a big hill, not even a small mountain.

[pfdietz]

It's my understanding that reduction of silica to metallurgical silicon, which is done in an arc furnace using carbon as the reductant:

SiO2 + 2C --> Si + 2 CO

is best done with charcoal, not coal, due to the porous microstructure of charcoal more effectively interacting with silicon monoxide vapor. So not only is coal not needed, it's not even the best feedstock for this process.