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Electricity Generation in Australia.
The Federal Government’s imposition of a carbon tax in Australia from 2012 has brought electricity generation sharply into focus. The civilised world depends absolutely on electricity because electric energy provides the simplest mode of operation for domestic and industrial machinery and for lighting. Electricity generation discourses always devolve into how to supply big cities; this article is concerned with supplying big cities, in Australia, and the industries located within them.
At the user end, electricity appears a ‘clean’ source of energy: no obvious emissions and, in most electrically operated machines, reasonable efficiency because of limited heat loss. Thus an electric car has no emissions and an engine which is much more efficient than a petrol engine because the petrol engine loses about 30% of its input energy as heat. The electric engine has a much lower rate of energy wastage. However the electricity used in the electric car must be generated somewhere
Trams are an important part of Melbourne’s transport system. Those who say that Melbourne’s tram system is a clean form of transport might like to go to the LatrobeValley where the electricity which fuels trams is generated. They would quickly discover air pollution is a problem and has been ever since the start of the industry. The electricity generated to run the tram system (and electric cars) is hardly ‘clean’ energy. Certainly the quick, quiet, commodious tram is a neat answer to the city’s transport problems but the pollution caused by its presence in Melbourne has simply been removed to distant Gippsland.
Whatever our view on Climate Change, most would agree that we need to reduce air pollution caused by electricity generation. Certainly power stations do a good job of reducing the air contamination but this is at the expense of further energy use. Pollution reduction gear needs energy to operate. 
Coal fired power stations convert about 30% of the input fuel energy into useable electricity. The other two thirds goes in heat loss and transmission losses. Generating electricity by burning coal is very inefficient. This is especially true of brown-coal fired stations where water has to be removed from the coal before it is burnt and when dry it produces less energy than black coal per kg. Efficiencies are improved in Victoria because the brown coal is close to the surface, can be mined easily and the power stations are next to the coal field. Neither of these factors, though, alters the fundamentally inefficient nature of the overall process.
Coal-fired power generation thus has two significant problems: pollution and inefficiency. However coal-fired power generation has served us very well for at least a century and is the main reason for the high standard of living enjoyed by us and the rest of the developed world. Reducing our dependence on it should not be at the expense of our standard of living. More about standard of living later.
Gas-fired power stations. 
These are the most viable alternative to coal and have all the advantages of coal use. They produce less air pollution and are more efficient; certainly more efficient than brown coal generation. But they still produce carbon dioxide so those concerned about climate change will not see such a great advantage in gas use.
Hydroelectric power
We have reached our capacity for this form of generation because building the dams necessary and altering water flows is no longer acceptable. 
Nuclear power
Nuclear power stations are very expensive to build and come with attendant risks of accident and potentially undesirable use of end products. To go down the nuclear pathway would involve a complete change in the way of thinking about generating electricity here which no political party has been prepared to embrace. We can probably reject nuclear power as a viable option politically in Australia. 
Geothermal generation
Geothermal resources remain largely untapped but the figures are impressive. We must wait and see what transpires. 
Tidal generation
Tidal machinery is expensive to build and maintain. It also has quite limited output compared to potential demand from cities. Tidal generation is not viable for large-scale generation. 
That leaves wind and solar generation. But firstly a word about base-load: base load power is the power we need to operate the city. We need it 24 hours a day and we need it when the sun is not shining and the wind not blowing. Unlike direct-current electricity alternating -current electricity cannot be stored in batteries. We produce alternating current electricity on demand. Thus we need to be able to produce alternating current at variable rates during the 24 hour-day to account for predictable fluctuating requirements. Coal-fired generation is ideally suited for this because we can vary the number of stations which are on line and vary the output of a station by burning less coal. This is one important reason why we have persisted with coal-fired generation. Another reason is probably the political clout of the energy companies and unions. 
So where does that leave wind and solar generation?
Wind Power
Wind is intermittent. So any wind power system has to be backed up with a supply system which can take over if the wind does not blow. Ways are being developed of storing energy in super-heated salt-water solutions but these will be inadequate for cities. We can also use power generated elsewhere in the national grid as back-up but any long-distance transmission involves substantial losses and thus reduces efficiency. 
To replace one large coal-fired station with wind turbines would need about 2700 large turbines (source: Wikipedia) which immediately raises the question of where these turbines would go? We have consistently seen locations turned down, essentially because of public pressure, and 2700 turbines is only replacing one coal fired station. Add in the problem of intermittency, and the need to maintain base-load generation, and it becomes clear that wind power alone will not be able to replace coal generation.
Solar Generation
To replace one coal-fired power station with solar panels, one square metre in area, would need about 343,000 such panels (source Wikipedia). Of course we could vary the area of the panels but it is still obvious that solar panels will not replace coal-fired powered stations. And, of course, solar panels only operate when the sun shines and brightly. They have the same intermittency problems as wind power. 
Because solar panel installation has only occurred in a minor way in Australia we have not seen the visual effects of large-scale installation. Given the fuss caused by wind turbine installation we could probably expect similar outcry against intrusive, large-scale solar panel generators. Of course panels could be installed in remote locations but this involves transmission losses when moving the power about.
Both wind and solar generation have significant drawbacks.
So where does all this leave us? Clearly we cannot replace coal and gas generation with renewables. Certainly we can supplement such generation with renewables, but notice that it is this way around! Supplementing renewables with coal/gas generation will probably not work because of the unpredictability of supply from the renewables. Coal and gas generators can not start up and begin producing immediately. They need notice. Holding them at ‘readiness’ reduces the delay but, of course, uses fossil fuel.
So what is the answer to our power generation dilemma?
Nuclear power would solve all the problems but would bring others. Geothermal is a great hope but much remains to be done. Wind and solar, even taken together, are inadequate for our requirements and problematic anyway. Gas use is a great improvement on using coal. 
Perhaps the answer lies in moving to gas-fired generation as far as possible and supplementing this with wind and solar.
Renewables can help but not completely replace fossil fuel generation for large-scale power generation.
Of course we could use less power by moving to less-energy-use lifestyles, building smaller houses and making large apartment blocks more energy efficient. And we should do this.  But these changes only affect domestic use, we still need to run our trams and electric trains, make motor vehicles and aluminium, run industry generally and light our streets. 
We will still need large-scale power generation even with the most efficient lifestyles.
12th of July 2011

My Engineer friend Frank has made the following comments.
Thanks Jack. A good summary of the situation. A couple of points I would make.
Firstly you do not distinguish between pollution and CO2 – the crux of the debate, I believe, to be the latter.
The distinction between the two however, brings into play the whole climate change debate - the real
need for an alternative strategy. Perhaps too little attention has been paid to the outcome of future
earth heating rather than just what will it really do and how do we live with it? Perhaps this is out of the
scope of your article though.
I believe the usage of gas as distinct from coal is a little short term bearing in mind oil reserves
are running out and alternative sources of portable energy will be needed in the future.
As an engineer I believe it possible to make nuclear generation near foolproof now-a-days. The drawbacks have been exaggerated to my mind.
Another alternative future scenario may be to concentrate on nuclear for fifty years or so to give time for the
Other forms of energy production to be developed to the point of being realistic and reliable.
The voices of reality will only be heard when power black outs become common place due to the lack
of investment in future generation. That time is nearer than we think.