SA researcher develops vertical axis wind turbine configuration

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Vaal University of Technology head of the Innovation Centre Jan Jooste has developed a new configuration of the vertical axis wind turbine, which he stated could realise a shift in wind energy generation from horizontal axis wind turbines, as well as signStill in the testing phase, Jooste’s configuration of the vertical axis

wind turbine consists of three blades over three levels, as opposed to

the single layer used in a conventional vertical turbine.


wind tunnel testing results, Jooste added that the new configuration

increases energy yield by 400%. This, he said, was because the two

additional layers increase the area of energy capture by 200%, and, as

the energy yield correlates with the area – the energy yield will

similarly increase by a further 200%.

“Initial results, as well

as theory, support a 400% improvement in energy harvesting, relative to

the conventional configuration of vertical axis wind turbines,” said


He said that a further benefit of the new configuration

was that blades were now continuously spinning through fresh wind with

higher energy levels. “In conventional vertical axis wind turbines, the

blades spin through fresh wind in the upwind half of their rotation –

but pass through reduced energy wind in the downwind half of the

rotation. The impact of this improved downwind half, seems to be an

overall increase of about 200% in energy yield.”

He explained

that this could realize a shift from the more popular horizontal axis

wind turbines, towards vertical axis wind turbines. “This shift would

also be supported by the fact that vertical turbine blades are much

easier to manufacture than horizontal axis blades, and blade

manufacture could also be automated,” Jooste noted.

He highlighted that a further change could occur in the entire energy generation industry.


would upset the approximate parity in generation costs per unit of

energy, between wind and coal. About 70% of the generation cost for

wind energy serves to recover capital cost. If capital cost could now

be reduced by 60%, the generation cost per unit of energy would drop by

42%, which would make alternative generation the rational choice, even

in the absence of subsidies,” Jooste reiterated.



have outgrown our wind tunnel. Next scale tests will involves driving a

truck along an airfield runway at various speeds, to spin two turbines

(conventional and high performance) mounted in a frame at the front.

Everything will be instrumented to measure the speed of incoming air as

well as the turbine rotation and power output,” said Jooste.


was expected that the measured 400% increase could decrease to about

300% at larger scale tests. Current tests were not conducted under

conditions that generate high confidence, however, larger scale tests

would be more reliable.

Discussion with various potential

funders was under way, although Vaal University of Technology would

likely fund the next phase of research. “Economic conditions

necessitate that a number of funders be approached,” noted Jooste.


holding company for the technology, Enerqi Technologies, has been

created, and intends to license the technology to manufacturers at an

affordable fee per kilowatt of capacity sold.


Technologies will not become a manufacturer, primarily as we cannot be

both a player and a technology provider in the market. Furthermore, the

market is just too big for a new player to make an impact,” said Jooste.


added that with a market of this size, and showing growth, it was

competitive, and would not be easy to collect royalties from such

players, however, he said that the prospect of a sustainable

competitive advantage would make the business case.

In terms of

energy generation, Jooste said: “We will be doing well to have a 100 kW

turbine running in two years time. Such a turbine will have a diameter

of 9 m, blade length of 8,33 m, chord of 0,75 m. Total blade height

will then be 25 m, and it will generate 100 kW over the 225 m2 swept

area in a 12 m/s wind to attain a coefficient of performance of 42%.”


should prove the technology as soon as possible and climb the learning

curve. High performance turbine power could reach 1 MW in five years

and should later reach the 2 MW to 5 MW capacity of current big

horizontal axis wind turbines,” said Jooste.

Although not often

seen in South Africa, Jooste noted that vertical axis wind turbines are

used in Europe and the US for urban electricity generation, but are no

longer used for utility scale electricity generation in the US and

Canada, where they were used from 1970 to 1990.

Vertical axis

wind turbines have vertical blades spinning around a vertical axis,

where-as the more common horizontal axis wind turbines, as found in

Darling, in the Western Cape, and across Europe, have three blades spin

around a horizontal axis.

Among the advantages of the vertical

arrangement are that generators and gearboxes can be placed close to

the ground, and that they do not need to be pointed into the wind.

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