Blowing for show

As their slogan says, ‘Every little helps’ but in the case of Tesco’s plans for wind generation at their Ocotal Way store in Swindon, it’s very little indeed. They like to puff that the output from the turbines is impressive.

This is part of our commitment to reducing the carbon footprint of our existing stores by 50 per cent by 2010…. Each turbine generates 6KW, enough to power four households, and reduce carbon emissions by 24 tonnes a year.

The reality is less impressive. Despite the spin, their spokeswoman seems not to know what impact these turbines will have.

What proportion of the Swindon store’s power could be generated by the turbines would depend on the size of the store.

Well, yes, but the proportion will always be virtually nothing. To get this in perspective, as the supporting statement to Tesco’s planning application says,

Given the intermittent nature of the wind it is generally assumed that wind turbines in the UK will have a capacity factor around 30%, meaning that they will, on average, generate power equivalent to around a third of this ‘Installed Capacity’.

So that’s just 2 kW per turbine… enough to boil a kettle. Three kettles’ worth of power is insignificant in comparison to the energy consumed by a large superstore. The supporting statement goes on.

A 6 kW turbine will, at its maximum, generate sufficient electrical power to supply the equivalent of around four average UK households, and would prevent, on an annual basis, the emission to atmosphere of 13.6 tonnes of carbon dioxide per year.

Only 13.6 tonnes? What happened to the other 10.4 tonnes that Tesco’s spokeswoman was talking of? It seems that Tesco’s press statements have even more puff than their pastry!

The real purpose of these turbines is demonstrated by their positions. As the plans show, the turbines are located around the store for maximum visibility, with one of them, contrary to the supporting statement, even being shielded from the prevailing wind by the store itself. This planning application has everything to do with Tesco trying to promote an image of being environmentally friendly and very little to do with serious renewable energy generation.