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So we now have the results of the Malta Resources Authority’s (MRA) reality show on deepwater offshore wind turbines in the shape of an expression of interest by 9 firms, less than half the 22 potential bidders originally mentioned by the MRA CEO (MaltaToday, 20 August). Information which surfaced after the call for expression of interest was published, said that an EU 6th framework project, with a consortium of German, Belgian and UK firms was setting up two large rotors in 45m of water near an oil platform in the Moray Firth, Scotland. That Italian “large scale mock up” (Maltatoday 20 August) was not involved – no surprise, as ‘mock-ups’ are not usually built to test any technology but mainly to decide on appearances.
One very real fact in this matter is that the dismissal of any onshore or shallow water offshore wind farms by MRA and their UK consultants has been shoddy, unscientific, and underhand. The report sent to Brussels but never published here provides ample evidence of that. For instance, Sikka il-Bajda off Armier point, is dismissed as having “marginal wind speeds” compared to unspecified “international off-shore sites” – a comparison unsupported by any indication of (useful) wind speeds or even which “international(sic) sites” are meant. At least one other extensive area was not even considered; but that could be because the MRA writ does not run in the whole area of the Republic of Malta!
The remark that a wind farm on Marfa ridge “is unlikely to produce more than 1-1.5% of the electrical energy consumed in Malta” (MaltaToday 20 August) betrays the local addiction to single, grandiose solutions. For a start, that would mean a real saving on our current fuel bill, part of which will be offset by the unit price we have to pay to the wind farmer. For onshore wind, that price is competitive now with fossil fuel unit cost, and the rotors can be brought on stream in a comparatively short time.
The deepwater situation is different. The “estimated cost” of 4c/kWh (unit) is not instantly credible as no details of the calculation were provided. The technology is still being developed, and on sites with a significantly better wind regime than our allegedly “marginal” ones. So the fraction of the time the farm can be expected to be producing its rated power may be quite low, and certainly lower than that in the Moray Firth.
However, there is another consideration that was apparently mentioned in the original MRA press conference but has been since buried. At the original MRA press conference, it was said that wind farm operation would require the cable link with Sicily to be in place. No explanation for this requirement was given, but it is not too difficult to make an educated guess. Coupled to our isolated grid of 570MW nominal power, a 100MW wind farm, with its inevitably variable output, can lead to serious instabilities.
A possible scenario has the wind farm producing close to 100MW and the conventional generators coping with the rest of the demand. Now over the space of some half an hour the wind dies down; those 100MW have to be provided by the conventional generators, some of which (steam turbines) are incapable of such a fast response from a cold start. Yet unless the demand is met, power cuts will occur. One solution is to keep an ample “spinning reserve” – generators running at low load which can respond rapidly to diminishing wind output. But with a 100MW wind farm that ‘spinning reserve’ may be of such a size as to wipe out all fuel savings from the wind farm!
The Sicily cable could act as a ‘spinning reserve’, assuming it has the required response time. But the new gas turbine and the Sicily cable are not going to provide a grid larger than the present one because of the projected closure of Marsa. Now a 1-1.5% wind farm will provide cheaper electricity and pose few if any problems with ‘spinning reserve’. Sited in shallow water, unit costs will go up slightly. But until the powers-that-be withdraw their anathema on such farms, we shall have to whistle in the wind.
Profs. Edward A. Mallia
Attard
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