Monday, 29 April 2013

Passing wind quietly

Having given thought to a claim by IBM that they are developing a game-changing solar PV technology (see Tipping point coming in photovoltaics?)  I felt kind of compelled to see whether the same might be happening in wind power generation.  As these things are prone to happen, there was a ready-made post in archdaily describing a project by a team from Australia’s University of Wollongong and marine engineering firm Birdon, to develop PowerWINDows – a new type of wind-to-energy conversion technology that they claim might be particularly suitable for use on urban skyscrapers.  Author leads off with:
"It seems like the natural thing to do, exploiting the height and shape of energy-consuming high-rises by installing wind-turbines to off-set power needs. However, past experience has shown that it’s not all that easy. Aside from generating power, turbines also generate noise, vibration and turbulence, which means they are ideally located in the countryside, or off-shore, miles away from civilization."
The point is well illustrated by London’s Strata Tower.  For the couple of years during design and construction, its developers claimed that the three structurally integrated axial wind turbines would provide up to 8% of the building's energy.  Since completion in 2010, a different story dominates the blogosphere; the turbines spend most of their time lying idle.

The University of Woolongong initiative tries a different tack.  The system is described as "an array of small panels arranged in a grid. Each panel is a miniature turbine in itself, which rotates with the direction of the wind, unlike traditional turbines which run perpendicular to it. By changing the direction of rotation, the wind the panels generate less noise and whip up less turbulence, they also place less stress on the supporting structure."

To date there has been a considerable body of literature which suggests that the wind regime of urban environments is too turbulent, and otherwise variable, to be actually efficient for building integrated wind power. In spite of the wonderfully evocative rendering of a gossamer-like array mounted between the Petronas Towers in Kuala Lumpur (look carefully at the image above), I am not holding my breath that this is the enabling breakthrough.

But I have also learned over the last few years that it is as dangerous to say something can't be done, as to prematurely claim success.

Finally, a gratuitous comment.  
is remarkably prolific on Inhabitat, and I feel churlish to criticize. But the Razor (as the Strata SE1 tower is known by Londoners) was by no means the first building to have conventional wind turbines integrated into its form.  That honour might belong to the Bahrain World Trade Center, with three wind turbines, which are located on three stacked bridges between the building's two towers.  At 29m diameter, they are not just much bigger than the three 9m diameter wind turbines on the Strata SE1, but were completed in the year that Strata started construction.

1 comment:

Philip Junaeus said...

The ide of harnessing winds within an urban area has a number significant problems associated with it. As winds sweep through the complex geometry of the modern day city, they are broken up and wind speeds are overall reduced.

Depending on the direction of the prevailing wind, they way it breaks up and flows through the city can only be thoroughly determined by the use computational fluid dynamics. This sort of analysis is incredibly expensive, and would require a high number of simulations to cover the majority of winds needed to be able to asses which winds, and which parts of the city a is suitable for harvesting.

One can also look at this system much like competitive sailing, where the aim is to overtake the other vessel by stealing it’s wind and putting it in a wind shadow. As the wind passes through these miniature turbines, wind speeds post harvesting is likely to be significantly reduced. This raises legislative problems, where a new system is put up that blocks the wind of an earlier system. This can be likened to overshadowing issues, but unlike the sun which travel along a continues path, winds change and are therefore hard to legislate.

Overall, this is a very complex way of harnessing winds that have a high uncertainty of success, high cost, problematic in terms of legislative issues, and also potentially disturbing to residents. Another issue to consider is the wildlife, and especially birds. In the article, the system is pictured spanning in between the Petronas Towers creating a huge barrier, blocking the flight path of birds. Do we really want to dead birds falling out of the sky as we walk through the streets?

Considering all these issues, doesn’t it make more sense placing wind harnessing systems like this in remote areas or out to sea?