Venturi inspires Energy Ball

A wind turbine that spins in a spherical formation increases efficiency and reduces noise, according to its Dutch developer, Home Energy.

The Energy Ball (pictured below) replaces the traditional rotors of a wind turbine with an egg whisk-shaped structure designed to funnel wind within the turbine’s blades.

Erik Aurik, Home Energy marketing manager, said the technology works on the Venturi effect, which is usually associated with the drop in pressure that results when a gas or fluid flows through a constricted space at speed.

The spherical ball uses that principle by constricting the wind, so causing the pressure inside the ball to drop. The low pressure means the air flowing around the ball is sucked in and this helps turn the rotor blades.

The rotor blades use more wind and the turbine has a higher aerodynamic efficiency compared with conventional wind-turbine designs of the same diameter, said Aurik.

Most modern wind turbines are designed with three flat blades and the turbine’s head moves in the direction of the wind, using a computer-controlled system.

The tips of the blades, which can reach up to six times the speed of the wind, make perpendicular slices through the air, causing a swishing sound that some people find annoying.

The Energy Ball rotors are bent around in a ball shape so they primarily move parallel to the wind, making it quieter than conventional wind turbines, said Aurik. ’The noise of the Energy Ball will never exceed the wind sounds.’

It can also operate at very low wind speeds. ’The turbines will start turning at 2m/s and the Energy Ball can start generating electricity at 3m/s,’ he said.

The turbine is being marketed for small-scale energy use for homes, communities, businesses and public facilities.

For these types of applications, Aurik said the turbine can be installed easily on a pole 10-12m tall or a flat roof in four hours.

Optimum results can be achieved if the turbines are installed 40ft above the ground in an area free from trees and buildings.

The Energy Ball, sold in 1m or 2m diameter sizes, costs £2,000 to £4,000.

The company estimates that in places where there are winds faster than 15mph, a 1m turbine could generate up to 500k/Wh a year, while a 2m ball can supply 1,750 k/Wh a year.

According to a 2004 report by the Building Research Establishment, the average UK household uses 3,300kWh of electricity a year, which means the turbine could be a viable source of domestic energy.

Aurik added that the company is considering increasing the scale of the Energy Balls. ’Generally, in wind technology, twice the diameter will give a four times performance,’ he said.

Alternatively, Aurik said the turbines could be clustered to provide even more power. ’Wind parks with many of these balls can be foreseen,’ he claimed.

Siobhan Wagner