Elephant & Castle turbines are blowing in the wind

02 November 2007

Surprising as it may sound, a dingy room in a top floor flat in south London could hold the key to London’s renewable energy plans.

In apartment 223 of Ashenden House, an 11-storey council block on the Elephant & Castle’s Heygate estate, monitoring equipment — including standard PCs and some curious wall-mounted gizmos — are testing the output of a wind turbine installed on the roof above. A chunky cable disappears up a crudely cut hole in the ceiling — the vital connection that ultimately links the turbine to the national grid.

It’s a strange sight — the feel is distinctly Mad Max — but the truth is that the experiment under way is part of a project that could change the look of our built environment and the shape of our city infrastructure. Furthermore, the team — an engineer, a small-scale energy company, an aeronautics firm, and a university department — suggest an entirely new form of project delivery.

Keen to embrace London’s 10% renewables target, Southwark Council is leading the 12-month trial to test the viability of building-mounted urban turbines, which is nearing the end of its first phase. In June this year, Photon Energy, which supplies and installs wind turbine and photovoltaics, erected a 6kW wind turbine on the condemned block — which will be demolished in two years to make way for the council’s new vision for the run-down borough.

As well as measuring the levels of energy generated, the impact of noise levels on nearby homes and the potential for vibration are also being monitored. In a few weeks this turbine — a traditional horizontal axis design with three sails manufactured by turbine supplier Proven Energy — will be replaced with rival firm Quiet Revolution’s apparently more efficient vertical axis model. Results from both will be tested, with the data collated and analysed by South Bank University, to be made available to interested parties.

Positive results for the turbines could inform the nature of developments being proposed for the area. And now that the Code for Sustainable Homes has stipulated new sustainable developments draw their energy from on-site supplies (News October 12), the project’s relevance has been given new impetus.

Data-gathering

So how are things going? Brian Dunlop is the engineer whose firm, Brian Dunlop Associates, has carried the project through planning and worked with aeronautics outfit Gas Dynamics to identify the best rooftop location for the turbine.

“There’s plenty of data for photovoltaic performance in urban locations,” he says. “But very little regarding urban wind power. From a planning point of view, we want to put to bed fears over noise and vibration, and so far the results have proved positive.”

Dunlop does add, though, that there is an enormous amount of data to be analysed. “The equipment used collects information every second using sophisticated software created by Gas Dynamics,” he says. “At the moment South Bank University is analysing data gathered from the first three months.”

While it is still too early to be conclusive, data so far suggest both good and bad news for the future. Noise and vibration have proved to be minimal — meaning planners have approved the installation of the Quiet Revolution this month, with the Proven Energy model relocated to a position above an occupied flat — but wind speeds have been disappointing. Despite the occasional blast of 12m per second gusts, the average recorded speed has been a measly four metres per second.

“You need at least five metres per second to make turbines of this size cost-effective,” says Michael Holmes, Photon Energy’s director responsible for managing the project’s construction programme.

Location counts

But if over a longer test period, higher winds were to raise the average speed, Holmes reckons the turbine could generate between 6,000 and 12,000kW per year — enough to supply the energy requirements of four Ashenden House apartments.

He adds: “Every day we’re learning more about urban wind flow. There are some basics — wind speed drops as it diverts around structures; the more buildings you have, the lower the wind speed; tall buildings behind turbines create excessive turbulence — but that’s why we’re doing this. We need to find out whether urban wind power is a worthwhile renewable energy source.”

Rupert Blackstone, an associate energy director at Arup, offers a similar perspective to Holmes.

“Modelling urban wind movement is a real challenge,” he says. “It’s almost impossible to be predictive because every environment has local characteristics that affect air flow. The surface roughness — meaning the variation in height of a neighbourhood’s buildings — has a huge influence on the wind resource available. There’s really no point in extrapolating from meteorological data — you have to be location-specific in your analysis.”

Back in the apartment the curious gizmos — two red, wall-mounted boxes labelled Windy Boy and Sunny Boy — demand an explanation.

“They’re inverters,” explains Holmes. “Put simply, Windy Boy synchronises the power from the renewable source for household use — converting the direct current from the turbine into an alternating current. It makes it compatible with the national grid.” Sunny Boy does the same for photovoltaics or solar panels. It’s not a stretch to say that such items could soon be as common in typical family homes as electrical and gas meters are today.

Externally, the impact of roof-mounted turbines on our skyline is clear. The Elephant & Castle turbine is visually striking and generally acceptable to Londoners, feedback shows — although a “forest” of them might elicit a less favourable response.

But this bold and necessary experiment could also turn out to be a red herring as Holmes, a genuine pragmatist, admits. “If it’s shown that the turbines don’t produce enough power we’ll have to consider other options for renewable energy.”

It will be another six months before we know.

The turbine is raised into position above the south London building.

Get the latest stories first with BD newsletters. Click to signup
							WHAT ARE THESE?

| DISCUSS IN BD'S FORUM | SUBSCRIBE TO BD

---

We want to hear from you
You can be as critical or controversial as you like, but please don't get personal or offensive, and do keep it brief and relevant. Remember this is for feedback and constructive discussion!
Comments may be edited if they do not meet these guidelines.

Tell us what you think

You must fill in all fields marked *

Story date 2 November, 2007

This field is for security, please leave blank.

Your Name*

Your Email*

Comment*