Category Archives: Renewables

Don’t Mourn Windsave

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Windsave, manufacturer of domestic wind turbine distributed through B&Q. went bust recently. Their Chief Exec blamed delays in implementing Government Policy, but I wonder…..

In their original marketing Windsave suggested their turbines would generate 1000kWh and provide “up to 30% of the electricity your household needs, based on average wind speeds and suitable locations”. For a £1,500 price tag this looked to a lot of people like a good deal, and many, including some reputable businesses were persuaded to part with cash.

Unfortunately the reality fell far short of the promises. A survey last year by the Energy Savings Trust found no instance of a micro wind turbine in an urban or suburban location which generated more than 200kWh per year. In some cases the control electronics consumed more mains electricity in the course of a year than was generated from the wind.

The failing was not Windsave’s alone; any rooftop turbine in an urban situation is in the boundary layer where airflow is turbulent and most of the energy has been dissipated through friction. It is simply not possible to generate any sensible amount of wind energy under these conditions.

Nevertheless Windsave seriously overstated the performance of their product. The public backlash started early, with numerous blogs by eco-enthusiasts describing woeful generation from their machines. Windsave were forced into serial retractions of their claims for performance and finally removed all performance information from their website.

If we mislead the public by overstating issues, when they discover the truth they will never afford us credibility again. It is crucial that we avoid doing this when it comes to debating renewables in the context of national energy policy.

Clarity on Performance

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Following the piece I did for BBC Country File on Feed in Tariffs, I found myself in an interesting debate in the letters section of New Civil Engineer. As usual, this started me thinking, this time about communicating sustainability to the public.

The standing of climate science is currently pretty low as it has become apparent that scientists overstated some of the issues. The same happens when Government makes overblown statements about the effectiveness of renewable energy in desperate attempts to meet its own policy targets.

The announcement launching Feed in Tariffs suggested that householders could earn £900 per year from installing PV. They failed to mention that this was only true for the South East of England, on a perfectly pitched roof, facing due South; hardly representative of the average. Further, such an array would be a little too large to fit on the roof of an average 3 bed terraced house and would cost £13,000-£15,000.

I believe that there must be much more clarity on the actual performance of real systems. We have already seen the market for DIY wind turbines killed off by public reaction to the overstatement of returns by manufacturers. This has reduced the choices for homeowners, even where these could have been installed in worthwhile locations. For engineers and Government to similarly hype up the potential returns from renewable energy does not do the industry any favours.

We need to build public trust and support for renewable energy by making realistic assessments of the returns they can expect from real installations, not theoretical ones.

Strata Tower

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The Strata Tower at Elephant & Castle featured heavily in the news last week. The developers are clearly very proud of their clever solution to addressing the London Plan’s requirement that 10% of a building’s energy be generated from on-site renewables. The building is to feature 3 turbines of 9m diameter for the princely cost of £1,300,000. However due to the small size and fixed direction these turbines are only expected to generate some 50MWh per year or just 8% of the building’s demand.

Let’s look at the alternatives:

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The well established Proven 15kW turbine has a rotor diameter of 9m and a single one of these costs about £50,000 to erect in a field. If sited in a suitably windy field you can expect to generate around 30MWh per year, but installations have been recorded that generate in excess of 50MWh. The same generation capacity as Strata for 4% of the cost!

On the other hand let’s consider Ecotricity’s turbine at the Ecotech centre in Norfolk.

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The first MW+ rated turbine in the UK this one weighs in at 1.5MW, and would cost about the same to install in today’s money as the Strata turbines. According to Ecotricity’s website this machine is generating 3,500MWh per year, 70 times as much as Strata is predicted to do!

This fad amongst local government to demand on-site renewable energy must stop; it’s eco-correctness gone mad! Rules like this force developers to waste money on eco-bling rather than investing in basic energy conservation and large scale renewables which can make a real difference.