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The system developed in the EU-funded REACH project sends an inflatable membrane wing up to 500 metres into the sky, tethered to a drum-generator module on the ground by a long high-performance plastic cable.
The new type of airborne wind energy system could accelerate Europe’s move to low-carbon energy. ‘We are convinced that we can reduce the cost of wind power substantially,’ says REACH project coordinator Roland Schmehl of Delft University of Technology in the Netherlands.
‘A flying kite uses 10 % of the material you need for a wind turbine,’ Schmehl says. ‘And as the whole system fits into a small container for transport and the generator is on the ground, it is easier to install and maintain,’ he adds.
Energy production is also potentially higher. ‘Compared to wind turbines, our kites can produce more regularly, leading to a higher yield, because they can go up to 150-500 metres and get to stronger winds,’ says Schmehl.
The kite operates in 'pumping cycles', where it alternates between reeling out then reeling back in. During the reel-out phase, the kite is flown in fast crosswind manoeuvres and pulls the cable from the drum, which generates electricity. Once the cable is at its maximum length, the kite is depowered and reeled back in using some of its self-generated energy, ready for the next reel-out phase.
Commercial launch is on the horizon. In summer 2017, a 100-kW pilot system was finalised – enough to power up to 200 small homes.
Schmehl and fellow engineer Johannes Peschel, CEO of enevate B.V. – a Delft University spin-off and another of the five-member REACH research-industry consortium – have filed a Dutch patent on the system and started the process for a European patent. ‘We aim to be ready for market by the end of 2020,’ they say.
Product pipeline
In 2017, the pilot was successfully tested by the Dutch Defence Ministry, keen to explore the system’s flexibility for off-grid use and to reduce reliance on diesel generators. ‘The return on the investment will be less than a year for them,’ says Schmehl.
In the same year, the pilot system was tested on the sea defences to the north of Amsterdam in the Netherlands as part of an art installation. The system proved to be comparatively silent, visually unobtrusive and posed little risk to birds and bats, Schmehl adds. REACH researchers are collecting further data in trials to map the system’s environmental impact. Remote communities and off-grid areas are its primary target.
‘The REACH technology can already compete with solar panels in remote locations where there are good wind conditions,’ says Peschel. ‘It can be combined with solar and batteries to create microgrids that provide a reliable supply.’
Large power companies are now ready to move into this area, according to Peschel.
‘Airborne generation is booming.’ He says that around 60 groups worldwide are working in the field, on 25 different concepts: ‘It will probably streamline to create great potential for cost reduction.’
The REACH consortium has networked with other researchers and businesses around the world. Members attended the Airborne Wind Energy Conference in Glasgow in 2019 to help to shape policy and research on kite-system technology.
‘Funding is healthy, but we need engineers,’ Peschel says. There are 24 staff working on the next stage of development at enevate B.V. alone – not just engineers, but also IT specialists and kite makers, maintenance staff and kite operators.
To this end, REACH has worked together with a Marie Skłodowska-Curie Initial Training Network, AWESCO, providing field test data and training to the network of postgraduate researchers.‘These are our future workforce,’ Peschel concludes.