A recent article in neweconomy claims that it is possible to remove the dependence on none renewable base load power based on a study from the UNSW (“Simulations of scenarios with 100% renewable electricity in the Australian National Electricity Market” Solar 12011, 49th AuSES Annual Conference, 30 Nov – 2 Dec., By Ben Elliston, Mark Diesendorf and Iain Macgill, UNSW.)
Now on the face of it this sounds possible, but what is possible on paper, or in a computer model, might not translate into something practical in the real world..
In fact one of the commentators on the paper has already pointed this out, see here, summary repeated below:
Ted Trainer; 21.3.2012
The paper outlines a supply pattern whereby it is claimed that 100% of present Australian electricity demand could be provided by renewable energy.
The following notes indicate why I think that although technically this could be done, we could not afford the capital cost. This is mainly because the analysis seems to significantly underestimate the amount of plant that would be required.
I think this is a valuable contribution to the discussion of the potential and limits of renewable energy. It takes the kind of approach needed, focusing on the combination of renewable sources that might meet daily demand. However it is not difficult to set out a scenario whereby this might be done technically; the problems are what quantity of redundant plant would be needed to deal with fluctuations in renewable energy sources, and what might the capital cost of this amount to?
The task is to supply 31 GW. The plots given show that at one point in time wind is contributing a maximum of 13.5 GW, but at other times its contribution is close to zero, meaning that other sources are backing up for it. The corresponding peak inputs from the other sources are, PV 9 GW, solar thermal 27, hydro 5 GW and gas from biomass 24 GW. Thus the total amount of plant required would be 75.5 GW of peak capacity… to supply an average 31 GW. (in his response to Peter Lang, Mark Diesendorf says their total requirement is 84.9 GW.) That’s the magnitude of the redundancy problem and this is the major limiting factor for renewables; the need for a lot of back up plant, which will sit idle much of the time.
In Trainer 2012 I derive the capital cost of plant capable of supplying 1 Watt from wind, PV and solar thermal, in winter at distance and net of transmission losses. When these are applied to the above GW supply tasks, the total capital cost is about $609 billion. This does not include the cost of the hydro and biomass sectors. If the biomass 24 GW is costed at the $800/kW Mark claims, this would add another $19 billion. My PV cost assumes tracking and Central Australian radiation, not fixed flat plate set up on rooftops, mostly located in much poorer sites.
And here in lies the rub - the unpredictability of renewable sources (like solar and wind) combined with the low utilization achieved makes them uneconomic to deploy at a scale necessary to 'cover up' that unpredictability and low utilization by sheer foot print alone...
Now I'm not against wind and solar, they have their uses, especially when you do not have access to any grid power - but using them to substitute efficient and predictable base load is not economically viable and won't be for a long long time at the current high costs and low utilizations.
There is also second problem here - that money spent on such green projects has its own 'environmental footprint'; someone had to work and consume resources to produce that money - therefore it should beholden to those who spend the money to see that the embedded resources consumed by producing it are as effectively utilized as possible. The money does not 'magically' appear - its a medium of exchange for services or resources consumed - we should NEVER forget that.