Energy Networks Australia and the CSIRO have released the final version of their roadmap for transforming Australia’s energy supply, to the usual fanfare that these things receive. If you’re not keeping close track, yes it’s different to the efforts from ClimateWorks and from GetUp, amoung various others. Why do there need to be so many anyway?
Anyway, the headline chart illustrates the phase out of coal, then gas, with build up of solar and wind to simply supply all of the terawatt hours we’ll need in 2050 (a terrawatt hour, TWh, is a billion kilowatt hours). Well it certainly looks simple, and at the very least we can seperate out the wedges of renewable energy and take a closer, more critical look.
Large solar PV
In other words, solar farms like the 102 megawatt (MW) Nyngan plant in NSW, which apparently generates about 230 million kWh per year. Judging by the shape of the dark blue wedge, enough of these need to be built by around 2035 to supply 45.6 billion kWh in that year. So that’s roughly 198 farms of that size. We already have Nyngan and a couple of other large solar farms which add up to at least the same output, so make it 196 solar farms in 18 years, or just about 11 per year. Starting now. Then, towards the end of the 2040s, we’ll need to roll our sleeves up again and start replacing these farms as they reach the ends of their expected service lives.
Again, at around the 2035 mark the light blue share of wind energy is set to begin expanding fast. How fast? To about 183.3 billion kWh through 2050, supplied by the equivalent of 172 windfarms the size of the 420 MW MacArthur wind farm in Victoria (Australia’s largest) at the national annual capacity factor for wind. With 15 years left to build them, we’ll need the equivalent of eleven and a half per year. This is well over 10 times faster than wind has been built in the last decade. Perhaps we can count some of Australia’s existing windfarms at the start of this period, but the fact is most of them will be reaching or passing the end of their rated lifespans in 2035.
By the Australian Photovoltaic Institute‘s upper estimate, there was a total national installed rooftop solar capacity of 5,968.341 MW in March this year. Ignoring the need for replacement by 2050 (let’s face it, nobody’s thinking about that anyway) and at the normal 15% annual capacity factor for Aussie rooftops, this is set to grow to 90,650 megawatts (to account for an annual 119.1 billion kWh supply) within 33 years, representing a monthly addition rate of close to 415.5 MW (it’s presently a bit over 60 MW/month) which would look like this:
The APVI also keeps track of the current proportion of Australian dwellings with rooftop solar by state. Simply scaling up these figures to roughly 100% for each state (i.e. tripling Queensland and South Australia, up to 10x for Tasmania and so on) yields 25,857 MW. That’s allAustralian rooftops with solar. Obviously we either need more houses or much bigger rooftop systems (probably both), however the CSIRO/ENA’s document is specific about assuming no further subsidies to incentivise addition, so all else being equal it’s not obvious why an individual household would install any more than the kW capacity that covers its own needs.
Two issues are left entirely unaddressed by the headline chart:
- A kWh of solar or wind doesn’t serve the same sort of demand as a “conventional” kWh, say from a gas power plant. The hundreds of billions of renewable kWhs appear to more than cover for coal and gas in 2050 at an annual timescale, but week-to-week, day-to-day supply is a different matter. Something more is obviously required when the weather won’t oblige.
- Storage of energy is the obvious solution on paper, and CSIRO/ENA foresee a plausible national capacity of 87 million kWh of batteries in 2050. Consider this figure against the 52,000 kWh installed in 2016, and the limited lifespan of these devices (even hoping for 15 years, this would require 5,800,000 kWh worth of battery capacity installed annually till 2050). This is precisely the approach critiqued in the recent review of 100% renewable energy scenarios by Heard and co-workers:
A common assumption is that advances in storage technologies will resolve issues of reliability both at sub-hourly timescales and in situations of low availability of renewable resources that can occur seasonally.
Battery storage is undeniably wrapped in buoyant optimism these days, even though recent large scale operational experience in California points to serious limitations. Additionally, the issue of lifecycle (generally only 10 years for lithium ion) emissions is almost universely neglected in “net zero carbon” scenarios which rely on battery storage. And ultimately, as recently stated by no less than Lazard:
Even though alternative energy is increasingly cost-competitive and storage technology holds great promise, alternative energy systems alone will not be capable of meeting the baseload generation needs of a developed economy for the foreseeable future. Therefore, the optimal solution for many regions of the world is to use complementary traditional and alternative energy resources in a diversified generation fleet.
To be entirely fair to the authors, the document contains some useful assumptions about future energy usage in Australia. It’s certainly worth a flick through. And they do try to account for the required build rate, however it isn’t quite as clear as starting a major new solar farm or wind farm virtually every month for the next three decades, and beyond, like I’ve elucidated here.
— Oscar Archer (@ActinideAge) April 29, 2017
Is the future of 2050 sufficiently far from foreseeable? How close do we get before we critically and honestly examine our progress, or lack thereof, and potentially reconsider other energy resources we initially chose to exclude? And how ambitious is 2050 anyway – when including all low carbon resources now may well significantly speed things up, if history is any guide?