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Air power will only blow hot and cold as state seeks grid boost

While a stick-figure army of windmills is set to invade the landscape thanks to the State Government’s new renewable energy policy, there is growing evidence that wind power will have little impact on the greenhouse crisis.

The problem, according to critics, stems partly from the erratic nature of wind, and partly from the political and economic realities of an energy market ever-hungry for economical power.

The result, according to the body responsible for allocating Australia’s east-coast electricity, is that wind energy, rather than reducing the state’s reliance on coal by adding to the total “green” power in the grid, instead displaces other forms of low-impact energy.

A spokesman for the National Electricity Market Management Company has confirmed that greenhouse-friendly power sources such as gas and hydro are likely to be the first to be shut down when wind energy enters the grid. The last to be displaced is brown coal, the worst for the environment but also the cheapest.

This and other revelations mean authorities both in Australia and overseas are questioning whether wind power is an effective source of reliable energy or largely environmental spin.

Even if Victoria succeeds in its goal of 10 per cent renewable energy (mainly wind) by 2016, the impact on greenhouse emissions is likely to be less than expectations.

Germany, for example, has one of the highest proportions of wind energy in the world and a report last year by grid operator E.ON Netz made the following warning: “Wind energy is only able to replace traditional power stations to a limited extent … traditional power stations with capacities equal to 90 per cent of the installed wind power must be permanently on line to guarantee power supply at all times.”

To start with, wind can only be guaranteed to supply 10 per cent of its stated capacity when needed. When a new wind farm is announced, claiming it can provide electricity to 50,000 homes, it only supplies that power in ideal conditions when the wind is neither too weak nor too strong. Overall, it can be relied on to produce power for 5000 homes, while back-up power must be available for the remaining 45,000.

Critics argue that wind’s attraction for politicians is its visible presence to a public worried about the environment, but largely ignorant of electricity demand, how it is generated and distributed, and its impact on the economy.

The problem is compounded by Australian industry’s reliance on cheap power. No one disputes that wind power is currently expensive – about $75 a megawatt hour – while traditional staple brown coal is at $35. But it can be reasonably argued that if the true long-term environmental and social costs of coal generation were included in bills, we would be paying two to three times as much as now.

But despite the State Government’s intentions, several factors diminish wind’s ability to deliver its promised greenhouse gas reductions.

First, wind farms reliably produce between 20 and 30 per cent of what is called installed capacity, meaning a wind farm capable of producing 100 megawatts will end up pumping out 20 to 30 megawatts over a given time. But it might not be pumping this out when there is much demand. That is why the 90 per cent back-up is needed.

Also, because wind is erratic – and because the energy cannot be stored – the Government wants to harness as much as possible when it is available. This means wind power has priority over other electricity generation. During normal to low demand, other generators will be closed down or their power sold cheaper. The first to go will be gas and hydro, They are the next-most-expensive to wind, but they are also relatively greenhouse friendly, so wind displaces generator forms that are already causing lower greenhouse harm.

The last to be displaced is likely to be the cheapest but the worst polluter, brown coal. It provides baseload of up to 90 per cent of the state’s power. Even the Government’s own paper from Sustainability Victoria, released to coincide with its wind farm announcement, admits: “At low levels of wind generation, more aggressive (electricity price) bidding by brown coal generators results in less of this generation being displaced.”

The National Electricity Market Management Company runs the national grid in the eastern states. When its head of corporate affairs, Paul Price, was asked, he confirmed that wind had priority and, when it was generating, would displace the more expensive, lower-polluting forms of power.

Because wind is erratic, as the Germans know, back-up is needed to maintain electricity grid stability.

This, according to Deputy Premier John Thwaites, is one reason why the Government is trying to place generators across as much of the state as possible – to try to have wind generation coming from at least somewhere at any one time.

There are other problems with wind displacing brown coal. Brown coal stations take many hours to increase or decrease output. But there is a potentially more crucial catch.

Richard Elkington, general manager for power at the state’s biggest generator, Loy Yang Power, admits that as brown coal stations reduce output, they start emitting more greenhouse gas in proportion to electricity generated.

“Brown coal stations are at highest efficiency when they are running flat-out, that is also when they produce their least greenhouse gas.

“Our station’s output is 2000 megawatts maximum and we can cut it to 1200 megawatts, but we produce more greenhouse gas per megawatt, the lower we go. Anything lower than that and the cost of generation starts to rocket dramatically.”

By Liz Minchin

The Age

5 August 2006