Therefore the energy equivalent of Diesel is received by one sq. m. with the sun shining on it at right angles with no cloud, pollution etc. every 40/2.7 = 15hrs.
The best you are likely to average per day is 5hrs. So, at 100% efficiency, you can produce 1 litre of Diesel from one square metre every three days.
Australia uses 54,000ML of petroleum products per year, or 148m litres/day Therefore we would need 450m sq m at 100% efficiency, which is 450 sq. km. Now let us be optimistic and hope to gain 10% efficiency, we would require 4500 sq km, which is a block 50km by 90km.
It's not much land for Oz, but it's a lot of water! Is there an oil producing algae that grows in seawater? What about that red bloom that appeared off Coogee Beach a few weeks ago?
