admin answers:

We already get our power from turbines, being steam, water and gas turbines. You mean wind turbines I guess. The southern coastline (Great Australian Bight) is a good wind zone I understand, so lets say it will produce 25% of the capacity of the wind turbines over a year. The UK achieves about 23% it is claimed.

Very large turbines are rated at say 5MW and might produce around 1.25MW on average.The size is 65m (each blade) and spaced 5-15 diameters apart, especially considering the row behind receiving the wake. This depends a lot on the land itself, but would look like 120m x 15 = 1.8km spacing which may be best for cost recovery with these very big generators. If the Nullarbor plain is taken as 1000km that only allows a row of 500 along the coast at most, with an average production like 625MW for the whole row. There can be multiple rows, but I have no idea how many are feasible. This whole row is similar to a single large coal fired steam turbine generator (600MW) A steam power station may have several of these. However there are other significant infrastructure issues, like the concrete used amounting to 1300m^3 each, the roads and the electrical distribution needed to cover long distances, how to replace or recycle all this. There is a strong likelihood that the grid needs an on line standby system of the same capacity, as well as a great increase in its carrying capacity in certain areas. This standby can be hydro (there isn’t anything like enough), though pumped storage could be built on some mountains far away (no mountains on the Nullarbor) or a bank of large gas turbines on line using methane or kerosene etc. Steam (coal fired boilers) generally cannot respond to sudden large changes in load if the wind drops.

The Australian production in 2009 was 261 million megawatt hours (second link). One row of generators as above would be around 5.5 million MWh a year, so it needs about 50 rows, stretching 100km inland. I am not sure the wind holds up that far even without 50 generators in the wake of each other.

This is a very rough estimate, but it seems to me it is not a very practical thing at all. Think of wind power as a fuel saver, something that is only useful in specialised areas like the southern coast line. In the tropics with cyclones and little winds otherwise to deal with, forget it, with any current technology. Normal winds are “very moderate”, while cyclones are up to several times the maximum rated speeds, and above the survival speeds. There are certain carefully chosen spots that do have wind generators in the tropics though I suspect these are more about political will than hard economic reality.

In the US estimates are that 20% of energy needs can be met by wind power. Australia could well be less than that. It may be one of the more expensive forms of providing energy, and not so clearly saving anything at all when all things are considered. The first link doesn’t have a positive view on these developments in Wales (UK), where politicians legislated that wind is the in thing. Politicians have law and art degrees. No surprise they make bad decisions about engineering, as they cannot tell who is stringing them along.

The second link might have other info of interest about load variation (change in demand) and aluminium smelters and refineries, and little known facts about the grid which appears to go to about Ceduna at the moment, so only the eastern part of SA is on the grid. WA has its own isolated grids.

The coal stations produce 78% of electricity and 200Mt (megaton) of CO2 a year of the estimated 30-35,000Mt of additional man-made CO2 a year in the world (according to the climate people). Where is the problem, one would ask. We export about 9% of this electricity as refined metals, with stuff like aluminium., and about 3 times as much coal as we use, also used for overseas electrical production in various countries that would be in a difficult position without it.

At present a mix of various energy types seems the best approach, with different situations in different locations. The best argument in favour of alternate energy is sustainability in the long term, but it seems that it will be very expensive compared to coal, close to Australia’s biggest asset. Should we just throw that away? Incidentally the alternative energy to suit Australia might be solar thermal.

admin answers:

Like the others say, it’s possible.

In June 2006, an agreement was reached to develop a 50MW solar tower generator, in which the sun heats air, which drives a turbine in a chimney, in New South Wales in Australia. The idea is not based on radically new technology. Chimneys with ‘smokejacks’ in which a fan in the hot air turned a roasting spit were certainly in use in the UK in the eighteenth century and probably before. It is well known that a tall chimney produces a better draught, presumably because there is a greater temperature difference between bottom and top, wind speeds are greater higher up, inducing more air to be drawn out of the top of the chimney by Bernoulli effects, and a long distance up the chimney should help hot air build up speed and kinetic energy.
But modelling all these effects and producing an optimally efficient design seems to be almost impossible, at least we have so far been unable to find anyone to take the task on.

If you are using a fluid medium, it could be more possible to make. Implied in your question though, is that we are looking at a vertical model for the turbine since you want to draw on the heat differential between a cold medium and a hot one.