Bob Brown, Christine Milne and their Australian Greens cohorts are big advocates for solar power - both photovoltaic (PV) and thermal concentrated solar power (CSP) farms. However, there has been a woeful lack of media scrutiny of the viability of these two technologies with regard to their practicality and cost effectiveness.
Looking at PV farms, the Federal Government has made a big song and dance about a new solar PV installation planned for Moree in NSW. The Government is claiming the new $923 million Moree plant, which will occupy about 11 square kilometres and have a nameplate installed capacity of 150MW, will be the largest PV installation in the world.
The Government claims that the Moree plant will generate 400GWH a year, an unusually high capacity factor of 30% as there are few PV plants anywhere in the world that have a capacity factor of more than 20%.
However, taking the Government at its word, how many $923 million PV plants like Moree would be needed to replace the first coal fired plant that the Greens have in their sights, Hazelwood?
The answer is quite simple to calculate. Hazelwood, which generates about 25% of the state of Victoria's electricity produces a bit less than 12000GWH a year. Therefore, leaving aside baseload considerations (PV plants only produce power when the sun is shining), it would take 30 PV plants like Moree costing about $30 billion just to replace Hazelwood.
Now let's consider what it would cost to replace Australia's electricity production with PV farms. Australian plants produce about 250,000GWH a year. Therefore, if we were to try replacing that with PV farms like Moree we would need 625 such installations costing more than $600 billion!
Of course, it's not as simple as that because PV farms do not supply baseload power - they only generate electricity when the sun is shining. Therefore, PV farms and rooftop installations alone can never be the solution to the energy needs of a modern industrialised society.
What about CSP farms that produce electricity by concentrating the rays of the sun onto a small area of a central tower which then heats up material to drive a steam turbine? Some of these plants actually provide significant energy storage so could they be the solution to the baseload problem with renewable energy sources?
Greens senator Christine Milne is a big advocate for "big solar thermal plants" so we should take a look at the state of the art of this technology today.
The poster child of CSP thermal technology is the $300 million Gemasolar plant in sunny Seville, Spain.
Gemasolar is really state of the art stuff when it comes to CSP plants. Not only does it use the sun's thermal energy to produce electricity but it is actually able to store energy in molten salts heated to 500 degrees Celsius for up to 15 hours. This storage capability gives the Gemasolar plant a capacity factor in excess of 60% - enough for it to be considered a baseload power plant.
So what does the ultra high tech Gemasolar plant provide for the $300 million investment to build it? Gemasolar is expected to produce 110GWH of electricity a year.
Therefore, it would take more than 100 plants similar to Gemasolar, costing more than $30 billion to replace the Greens' pet hate dirty coal fired plant, Hazelwood.
To replace all of Australia's electricity capacity with CSP plants like Gemasolar would cost something in the order of $680 billion!
That's about 17 times what the Government is proposing to spend on the national broadband network.
Of course, part of Australia's electricity needs are already serviced by the proven and viable renewable hydroelectric technology. Australia produces about 16,000GWH of affordable electricity, or about 6.5% of its power, from renewable hydroelectric sources, so only about 93.5% of the nation's power needs - 234,000GWH a year - needs to be replaced by other types of renewable energy.
In fact, the economics of wind power are considerably better than the solar alternatives.
Wind has definite advantages over solar in that the wind blows during the day and night giving a resulting higher capacity factor for wind installations of about 35%.
One of the big wind power projects is the proposed Liverpool Range wind farm in the Hunter Valley of NSW.
The $2 billion Liverpool Range project will consist of 550 huge wind turbines spread over an area of 2000 square kilometres, expected to produce about 4000GWH of electricity a year.
Therefore, to shut down Hazelwood would require three wind farm projects the size of Liverpool Range costing about $6 billion. To replace Australia's coal fired capacity with wind would require the equivalent of 60 plants like Liverpool Range for the cost of $120 billion. On the surface this might appear to be very expensive but at least feasible - certainly more feasible than solar.
However, there are considerations with wind.
Leaving aside the huge amount of land required for wind farms, the primary thing to consider is that wind, like PV, does not provide baseload power - there still needs to be power sources available for when the wind is not blowing.
Given the above facts, it would seem that if Australia is to seriously consider a large scale conversion to renewable energy then the only feasible solution is wind supplemented by some form of low emission non-renewable baseload power source.
Since the Greens hate zero-emissions nuclear power, the only real alternative is non-zero-emissions gas fired power, which would need to provide at least a good percentage of the capacity of the unreliable wind power to make sure the lights don't go off at any given time of the day or night. This would probably at least double the cost of replacing all Australia's coal fired plants with wind to more than $250 billion and still not solve the problem of the Greens' bugbear of CO2 emissions.
Of course, there are other alternatives to the Greens' massively expensive vision of trying to replace Australia's cheap coal fired power plants with wind, solar or some combination. At some time in the future, cheap alternative technologies will emerge - perhaps nuclear fusion, hydrogen or something yet to be discovered.
However, right now, with the rest of the world happy to buy Australian coal to fuel its power needs, it seems not too far shy of lunacy to even consider bankrupting our economy by replacing our cheap and abundant energy sources with outrageously expensive, unproven, unreliable, and limited power technologies.