The world's largest solar farm

The world's largest solar plant has just been opened in India.  It's in Tamil Nadu in the south, where insolation is high, but not as high as in inland Australia. It has a capacity of 648 MW (megawatts), and will produce annually 1/6th of the power of the new Westinghouse AP1000 nuclear reactor, the kind being installed at Plant Vogtle in Georgia, USA.  Except that the solar farm took just 8 months to build, while a typical reactor will take 4 to 6 years (or longer--the new units at Plant Vogtle will take 7-8 years even without the planning and permitting stage), while leaving behind toxic by-products with a half-life of thousands of years. The project is comprised of 2.5 million individual solar modules, and cost $679m, or about $520K per MWh of annual output.  By contrast, the Plant Vogtle's new units will cost $880 per MWh (annual output per unit 7900 MWh, cost $7 billion.)  That's just the capital cost; running costs for solar would be very low because there is no fuel cost and  maintenance costs for fixed array solar panels are negligible. [Read more here]

The Topaz Solar Farm in California produces 1,100 GWh of power per year and is a about 1/5th smaller than the Tamil Nadu plant. So a single solar farm the size of the Tamil Nadu one (remember Australia has solar resources better than  India's or California's, so output should in fact be higher) would provide enough power for about 226,000 average Australian homes, as average per household electricity usage in Australia is 5817 kWh per year.  Australia has 5,453,000 households, so 24 such farms, costing a total of about US $16 billion, would provide power for all of them.  In practice, much of the PV capacity would be on rooftops of houses, schools, factories and shopping centres, not in solar farms.   Residential consumption is 25% of total Australian electricity consumption.  So for $60 billion, we could have 100% green electricity.

We will need storage for the evening and the morning peaks.  The latest version of the Powerwall battery from Tesla stores 14 kWh per battery, and costs US$5500.  So to provide the storage equivalent of one Powerwall per household, which would store a bit less than  a household's daily demand, US$30 billion would be needed.  However, although the Powerpack industrial-scale battery pricing hasn't been revealed, it will likely be about half the cost of the retail product.  Which means for $30 billion half of our total daily demand from all sectors could be backed up by batteries.

Let's do it over the next 20 years.  That amounts to US$4.5 billion a year, but progressively less in future years as solar and battery costs continue to fall.  That's less that half a percent of GDP.  And we would have to spend some of that money anyway, because our generating fleet of coal power stations is getting old and will need replacement.

I've ignored existing renewables, I haven't included the likely construction of several CSP (concentrated solar power with storage) plants, or the cost of new interconnectors between the eastern seaboard and South Australia with its rich wind resources.  But the picture is clear enough.  In twenty years we could reach 100% renewables for a tiny percentage of GDP.

The current Liberal-National government's policy is the utterly feeble Direct Action, which involves paying polluters not to pollute.  The government spends its time denigrating any move towards renewables and telling lies about how much renewables would cost and how they would damage "energy security".  They ask why we should do anything when India and China are not.  But next year India will become the third biggest solar operator in the world, and despite having 7% a year growth in electricity demand, expects to produce 40% of its power from renewables by 2030.  China is already by far the largest installer of wind and solar in the world, and for the last couple of years the growth in electricity demand has been more than supplied by renewables plus nuclear.