Three recent papers by Elliston, Diesdendorf and MacGill (2012, 2013a, 2013b) elaborate on a proposal whereby it is claimed that 100% of present Australian electricity demand could be provided by renewable energy. The following notes add considerations arising from the last two papers to those discussed in my initial assessment of the first paper. My general view is that it would be technically possible to meet total Australian electricity demand from renewables but this would be very costly and probably unaffordable, mainly due to the amount of redundant plant needed to cope with intermittency. This draft analysis attempts to show why the cost conclusions EDM arrive at are probably much too low.
Ted notes the following:
These efforts have taken a huge amount of time and I am still not clear and confident about my take, mainly because neither party will cooperate or correspond. Thus I have not been able to deal with any misunderstandings etc. I have made. Both critiques are strengthened by information I have come across since circulating previous commentaries, but they are essentially elaborations on the general line of argument taken in earlier attempts.
I find this unwillingness to engage on these criticisms by the primary authors disappointing, but typical.
I think these three papers are valuable contributions to the considerable advance that has occurred in the discussion of the potential of renewables in the last few years. My understanding of the situation is much improved on what it was three or four years ago and I now think some of my earlier conclusions were unsatisfactory. EDM take the appropriate general approach, which is to look at how renewable technologies might be combined at each point in time to meet demand, or more accurately, to estimate how much capacity of each technology would be required, especially to get through the times when solar and wind input is minimal. EDM put forward a potentially effective way of coping with the problem of gaps in their availability via biomass derived gas for use in gas turbines. My earlier analyses did not consider this.
It is not difficult for an approach of this kind to show that electricity demand can be met, and many impressive 100% renewable energy proposals have been published. (For critical analyses of about a dozen of these see Trainer, 2014), but a great deal of redundant capacity would be needed, and the key questions are, how much, and what would it cost? My present uncertain impression is that Australia might be able to afford to do it, but if it could it would be with significant difficulty, i.e., with major impacts on lifestyles, national systems and priorities, and on society in general.
A major disappointment with the EDM analyses is that for some crucial elements no data, evidence or derivations are given and as a result the proposal can only be taken as a statement of claims. We need to be able to work through the derivations in proposals such as this to see if they are sound or what questionable assumptions might have been made etc. Consequently I have had to spend a lot of time trying to guestimate my way to an assessment of the cost conclusions and it is not possible to confident about the results.
A merit of the EDM approach is to take as the target the present demand. This avoids the uncertainty introduced when attempting to estimate both future demand and the reduction in demand that conservation effort etc. might make.