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Wind Power Looks Like So Much Hot Air

Wind power looks like so much hot air

Date: 06/11/2004
Words: 1056
Source: AFR




Publication: Australian Financial Review
Section: Business
Page: 14

Any system that can generate only an average 11 per cent of capacity is hardly worth having.

Wind power is of little practical use, judging by a recent report from Germany.

The report should carry some weight among environmentalists in Australia because Germany is the world leader in windfarms. One-third of the world's wind-generating capacity is installed in Germany, much of it around Schleswig-Holstein near the Danish border.

The report says conventional grid power is needed to back 80 per cent of the installed capacity of windfarms, which casts doubt upon their necessity.

The report also found the winds blew most strongly in autumn and spring but were relatively calm in mid-summer and mid-winter when energy was most needed.

If climatic conditions in Australia parallel those in Germany, the report will cast doubt on the subsidisation of windfarms here through the MRET (mandatory renewable energy target) scheme.

It might also make raiders think twice about a bid for Australia's leading renewable energy company, Pacific Hydro, which has recently been the subject of takeover speculation.

The report is by E.ON Netz GmbH, the owner of the grid system that includes 44 per cent of Germany's installed windfarm capacity. (That equates, incidentally, to more windpower than is installed on the entire American continent).

The main point of the report is that, because the wind does not always blow, the windfarms need to be backed by conventional sources. It says: "In order to cover electricity demands, traditional power station capacities must be maintained as so-called 'shadow power stations' at a total level of more than 80 per cent of the installed wind energy capacity, so that the electricity consumption is covered during economically difficult periods."

The report says only limited forecasting is possible for infeed, the amount of electricity that wind power can feed into the grid, which fluctuates greatly.

The accompanying smaller graph shows the availability of energy feed from E.ON's windfarms during 2003. The vertical axis shows the amount of power contributed by windfarms. The horizontal axis shows the time for which it was generated, in quarter-hours.

The maximum feed was 4980 megawatts, which represented 80 per cent of installed capacity. But that was exceptional. The average feed was 969 Mw, representing a mere 11 per cent of capacity. Any system that can generate only an average 11 per cent of capacity is hardly worth having.

Worse, the strongest winds were the most inconsistent. The bigger graph shows an example of the wind power infeed pattern during a week of high winds (April-May 2003). The graph shows wind strengths can change quickly and vary widely. The maximum gap between peaks and troughs was 4340 Mw almost three-quarters of installed capacity or equivalent to six to eight large coal-fired power stations.

Fluctuations of this magnitude must have been a nightmare for the transmission system operators who were trying to maintain smooth supply.

The E.ON report says the experience of 2003 showed that whenever electricity consumption was comparatively high because of cold winter or hot summer periods, wind power plants could make only a minor contribution towards meeting demand.

These various factors caused problems for the entire grid. The report says the increased use of wind power in Germany meant that more conventional power also had to be installed as back-up, resulting in rising grid costs.

This implies that windfarms could not have reduced greenhouse gas emissions much, if at all, in Germany because old-fashioned hydrocarbon-fired power stations must have had to keep chuffing away in reserve for anywhere between 50 and 80 per cent of windfarm capacity. It also implies that if windfarms were allowed to become too large a component of a grid system, they would unbalance it.

How applicable is this report to Australia?

Wind directions and strengths vary enormously throughout the year in different parts of the country, but overall they would seem to suffer the same vagaries as in Germany, in that the winds don't blow all the time and strong winds tend to come in periods of gusts. At a public forum held by the Victorian Energy Network Corporation (VENCorp) in August, data was presented on the three days of highest demand in Victoria in 2003-04, which were December 9, 16 and 17.

On December 9 and 16, demand reached its peak at 4pm. At that time, the energy generated by the windfarms was at or near its lowest for the day. On the third day, thanks to a hot northerly, the supply from the windfarms peaked at peak demand time, but was well down for much of the rest of the time while demand was high.

This is backed up by the Bureau of Meteorology, which says the strongest winds around the Victorian coast tend to be in August-September, which is not when wind power is most needed.

There is also high variability in Victoria, where a storm might blow at a peak of 100 kmh, but the peak might last anywhere between one and six hours.

This should be a matter of concern, because Victoria is the state where the most wind farms are being installed, many of them by Pacific Hydro.

Three weeks ago, Pacific Hydro (which is big in hydro and wind power) was grizzling because the federal government had decided to maintain a 2 per cent MRET.

Pacific Hydro managing director Jeff Harding threatened that this decision would move about $1 billion dollars of renewable energy investment offshore and urged that the MRET should have been lifted to 5 per cent (a figure promised by Opposition Leader Mark Latham).

On the evidence to date, wind power should be treated as guilty until proven innocent and dumped from the MRET scheme until somebody can demonstrate that it's economic.

The fact is that neither wind nor solar energy is likely to prove economic until we have an efficient electricity storage system that works on power-station scale.

The feds would therefore be better off taking a hard look at some of the possibilities on the storage side, including vanadium redox and zinc bromide batteries.

Otherwise, they're just chucking away money through the MRET scheme in a token gesture to the green vote, which the last election proved they don't need