Wind farms and renewable energy

I would like to support the contribution of George Debono, The Wind Farm Solution, as well as that by Edward A. Mallia, The Energy Budget", both published in The Times on November 8. I think both deserve very serious attention.

The November special issue of the Proceedings of the Institution of Civil Engineers is devoted to Sustainable Power - The Role for Engineers, with a substantial part on wind power, while November's issue four comprises another important paper on the same subject, also featured on the cover page.

Worldwide, wind power has grown at an average yearly rate of almost 30 per cent over the last decade to reach 48 GW at the end of 2004. Wind turbines have steadily grown in number and in size and 5 MW (1 GW = 1,000 MW) prototypes have been erected.

Germany's wind power installation is at present the world's largest at 17 GW, but west Denmark's 2.4 GW is equivalent to 0.88 kW per capita, making it the most wind intensive in the world. Germany, by comparison, has only 0.21 kW per head. Spain has 8.2 GW and the US has 6.7 GW installed.

On a recent visit to the North Sea and the Baltic I was greatly struck by the large number of wind turbines, stretching for miles and miles both on the German and the Danish sides. I must say I did not find their impact on the view of a rather monotonous coastline at all unpleasant. The old wind water-pumps were a feature of the Marfa landscape and the myriad of windmills of Holland are extremely picturesque.

The UK, as at July 2005, had 107 onshore and three offshore wind farms, with a total installed capacity of 1.1 GW and another 0.8 GW under construction. The 60 MW 30-turbine North Hoyle (Liverpool Bay) wind farm, completed in 2003, was the UK's first major offshore wind farm. The official aim is to have 10 per cent of the total energy requirements for 2010 met from renewable sources (15 per cent by 2015 and 20 per cent by 2020) with 75 per cent of the renewable energy being wind power.

Technical issues include wind speed and predictability, wind shear, (the change of wind speed with height), turbulence intensity, accessibility and grid connection. Turbine sizes have tended to increase in size since 1980, becoming more cost-effective.

The current upper limit of 90 metres rotor diameter tends to increase to 140 metres, with proportional increase in height and diameter of towers. The current spacing of 500 metres may also have to be increased. Logistic and technical considerations may compel us, in Malta to go largely offshore.

Other and much larger countries have the potential for hydro-electric power, or for harnessing the tides for a similar purpose. Apart from solar energy, which we do not take seriously enough, we can only exploit the wind and possibly, but it is a long shot, wave power.

I recollect that half a century ago the late J S Savona MIStructE, a colleague of my PWD days, had contrived a small apparatus which could light a bulb through the vertical motion of floats placed in the sea. Studies for the exploitation of wave energy have been carried out in other countries but its viability is still to be proved.

Faced with the disasters which pollution is causing to the world climate, the escalation in price and the impending exhaustion of the traditional carbon-based fuels, we have to go for the clean renewable alternatives at all costs. Frankly, the capital costs are high but it should be possible to obtain assistance from the EU or other sources as a matter of global survival.