Hi Hasbeen, the same argument applies to all the other inputs as applies to the PV materials. There is a ramp-up period of energy investment which has to be supplied from fossil fuels (carbon or nuclear), but the system can then become self-sustaining to a very large extent. It's a bit like lighting a fire, really. Whether there can be 100% reduction in CO2 emissions is not really a relevant question as long as the net reduction can be large.

I'm not going to get into an argument about climate change, there are many other good reasons to conserve fossil carbon. Every kilogram of CO2 released through burning highly reduced fossil carbon is just under 250g of fossil carbon lost to the atmosphere and hence made extremely costly to recover. It is possible to manufacture methane and other reduced carbon species from CO2, but it takes a lot of energy to reduce the oxidised form.

Joe, those are all important considerations, but a full accounting has to include the "savings" made as well. For example, how much copper and aluminium might be recovered from a distribution network that is downsized and converted to DC? What would be the energy savings as a result of not having to refine those metals from scratch (about 95% in the case of aluminium, including resmelt)?How much central generation and the losses associated with its distribution might be eliminated? How much will demand decline during the projected life of a new generator? And so on. These may all be modelled, but I am certainly not going to try to do it now.

The ERoEI that Peter Lang relies on is based on dodgy assumptions that really don't hold up. He is undoubtedly sincere, but just as undoubtedly, he is wrong.

Rhosty,

“Joe, I don't pretend to know as much as Craig on this topic, but I do know something about power supply and how its made; with i.e., average transmission and distributions losses from current coal fired power, being in excess of 50% or in total, around an averaged 67%?”

You know much less than you think you do. You overestimate transmission and distribution losses by an order of magnitude.

Hi Craig,

Yes, the total CO2 outputs from all of the factors of production in the manufacture of renewable forms of energy, and including the savings as you say.

Is that production of CO2 less than what would have been produced using coal, compared to the total CO2 produced over the life of those forms of energy generation ? Has anybody done that sort of study ?

Joe

Joe, I can't point you to such a study, although I'm sure there must be some in existence.

I would suggest, however, that given the much smaller quantity of non-renewable inputs, it is unnecessary to perform a comprehensive study to come to the conclusion that the amount of CO2 released is also proportionally smaller. If you have figures that contradict that I'd be interested in seeing them.

As PV is increasingly integrated into building envelopes, the relative amount of CO2 release is going to come down still further.

Wind and other renewables like hydro (which is really more of a storage than generation technology) present different problems to model, but once again, if the power required to produce the products that go on to make more power is not derived from non-renewable sources, then it is obvious that there will be less CO2 released than for equivalent amounts of power produced from such sources.

Basically, it's an interesting question and one which should be readily answered, but the absence of a definitive answer is not a bar to proceeding on the basis that the exact quantum of reduction is unknown. It's much more important for carbon trading.

Hi Craig,

I don't have any figures for anything, that's why I'm asking :) My question is: in the total manufacture and maintenance of solar panels, wind towers, go to whoa, and in their dismantling, replacement, disassembly, etc., how much non-renewable energy is required and so, how much CO2 is produced, in order to produce non-CO2-producing forms of energy ?

I suppose a related question would be: how much energy would be required from renewable sources, in order to produce, go to whoa, those means of renewable energy ? Would they require more energy to produce than the panels, towers, etc. eventually produce themselves ? Is there a net loss, or gain, of energy involved ?

Pretty stupid questions from an engineer's point of view, I'm sure.

Joe

Joe, not CO2 but energy at http://festkoerper-kernphysik.de/Weissbach_EROI_preprint.pdf
Draw some conclusions from this.

Also, see reference to this paper at http://bravenewclimate.com/2014/08/22/catch-22-of-energy-storage/

An argument that subsidizing PV's is bringing the price down to the point of standalone viability, by one of Australia's most vociferous wishful thinkers: http://www.businessspectator.com.au/article/2015/5/25/policy-politics/grattan-says-solar-10-billion-waste-id-agree-if-it-was-still-2009. Still no reflection on the need for storage. What's it with these guys ignoring it? IMO it certainly can't be if we're to go far down the RE path. It's a blind-spot that completely undermines the clean future we're supposedly aiming for. Storage lowers the EROIE of PV's to virtual uselessness, with little prospect that technology breakthrough will improve the equation greatly (Prieto & Hall).

Re subsidie, if the price is coming down why are we still subsidizing as if it isn't?

Some Minnsy whimsy: "There is a ramp-up period of energy investment which has to be supplied from fossil fuels (carbon or nuclear), but the system can then become self-sustaining to a very large extent. It's a bit like lighting a fire, really. "

Really? No, the match continues to burn once struck because the reaction is massively exothermic compared to the activation energy, i.e. there is enough return on the energy input.

Think EROEI. Striking the match with nuclear and/or fossil fuel will get it started, but then it burns out because there is too much competing for the RE output for enough to be placed into building more RE infrastructure. Something has to give, either man trims back his civilization considerably to afford it, or the fire goes out.

Of course, continuing supply of FF and nuclear will mask this until it's too late to do anything about AGW in the time we have left to deal with it