Published: 17 April 2015
Cheap and renewable electricity anywhere
Most wind energy comes from turbines 150 metres above ground level. Winds at this altitude are however weak and intermittent, with most wind farms operating at only 25 - 30% of their capacity. EU-funded researchers have developed a prototype wind energy system that works at much higher altitudes, where winds are stronger and more constant, increasing electricity production dramatically. A commercialised product is in the pipeline.
© carloscastilla - Fotolia
The EU-funded HAWE system is a floating airship anchored to a ground station by a tether cable. The airborne module – or ABM – constantly rotates and is pulled upwards by an aerodynamic force known as the “Magnus Effect”. HAWE is a hybrid platform using buoyancy and lift. Its tether cable transmits this force to a generator at the ground station, where it is converted into electrical energy.
Low construction costs
The system does not depend on high, exposed sites or coastal areas to operate, so it can easily be deployed out of sight, or in remote locations, both on and offshore – even in deep water. The concept therefore avoids aesthetic criticisms often directed at standard wind turbines – that they are an eyesore, spoiling the countryside. Moreover, the ABM's altitude can be changed depending on wind speed to maximise energy capacity.
“As the system operates well over 200 metres above ground, any visual pollution is minimal,” adds project coordinator Nuno Fernandes from high-tech R&D company Omnidea in Portugal. “Also, construction costs are low as there is no need for giant steel and concrete towers.”
HAWE's inexpensive and aerodynamic materials provide a strong, gas-tight envelope surrounding the ABM, which can withstand the pressures of each operating cycle. Key features include a winch operating at speeds of up to six metres per second, plus a multifunctional cable able to withstand the ABM's forces and capable of transferring high voltage power and data. In addition, a dynamic communications and control system allows for automatic or semi-automatic operation.
Reaching the next level
According to Fernandes, intensive testing carried out at an air force base has validated the prototype and provided a sound basis for scaling-up the technology. And HAWE's already low construction costs are expected to fall further as the project comes closer to commercialisation.
In fact, lead partner Omnidea is actively looking at ways to propel HAWE to the next level, which would see a commercialised product available on the market.
The company has also identified some spin-off opportunities for a stationary platform that could be used in environmental and security monitoring; intelligence, surveillance and reconnaissance; wireless communication and satellite data validation.
Europe’s proximity to tropical latitudes, where winds are typically strong, puts Europe in position to reinforce its global leadership in wind power through innovative technologies such as those developed by HAWE. A commercialised product could also offer Europe high security of supply and a cleaner environment.