Alphabet-owned Makani tests kite power generation

The idea behind Alphabet's Makani (acquired Google in 2014) will take place in sending high-tech kites (tethered drones) hundreds of meters into the sky to generate electricity using constant winds. Thanks to such technologies, even round-the-clock production of wind energy is possible. However, the technology needed to fully implement this plan is still under development.

Dozens of companies and researchers dedicated to creating energy technologies high in the sky gathered at a conference in Glasgow, Scotland last week. They presented the results of research, experiments, field tests and simulations describing the viability and cost-effectiveness of various technologies collectively described as airborne wind energy (AWE).

In August, Alameda, Calif.-based Makani Technologies flew demonstration flights of its airborne wind turbines, which the company calls power kites, in the North Sea, about 10 kilometers off the coast of Norway. According to Makani chief executive Fort Felker, the North Sea test consisted of a glider launch and landing, followed by a flight test in which the kite remained airborne for an hour in strong crosswinds. These were the company's first oceanic tests of such wind turbines. Makani does, however, fly offshore various versions of its energy kites in California and Hawaii.

“In 2016, we started to launch in crosswinds – in this mode, energy is generated in our system – our 600 kW kites. We used the same model for testing in Norway,” said Mr. Felker. By comparison, the second most powerful wind-powered kite under development today is capable of generating 250 kilowatts. "Our proving ground in Hawaii is focused on building a power kite system for continuous autonomous operation."

Norwegian trials demonstrate the benefits of AWE. Built in part by Royal Dutch Shell Plc, Makani's 26m M600 prototype requires only a fixed buoy to operate. A traditional wind turbine experiences much more severe wind loads on its massive blades and must be placed firmly on structures that are anchored to the seabed. Thus, the waters of the North Sea, where depths reach 220 meters, are simply not suitable for traditional wind turbines, which can usually only operate at depths of less than 50 meters.

As CTO Doug McLeod explained at the AWEC2019 conference, the hundreds of millions of people who live near the ocean do not have shallow water nearby and therefore no offshore wind power. “Currently, there are no technologies available that could economically use wind energy in such places,” said Mr. McLeod. “With Makani technology, we believe it will be possible to exploit this untapped resource.”

The buoy for the M600 airframe was made from existing materials for oil and gas platforms, he said. The M600 is an unmanned monoplane with eight propellers that lift the drone into the sky from a vertical position on a buoy. Once the kite reaches height - the tether currently extends 500 meters - the engines will shut down and the propellers become miniature wind turbines.

AWEC2019 co-organizer and associate professor of aerospace engineering at the Delft University of Technology in the Netherlands, Roland Schmehl, said that eight rotors of 80 kW each allowed the company to create an impressive system that will be difficult for other companies to surpass. “The idea is to demonstrate the practical possibility of flying at sea with such a 600 kilowatt kite,” he said. “And the sheer size of the system is hard for most start-ups to imagine.”

Makani chief Fort Felker noted that the purpose of the August test flights in the North Sea was not to produce power close to the rated generating capacity of the airframe. Rather, the company was gathering data that Makani engineers can now use to run even more simulations and tests as they further develop their system.

“Successful flights have confirmed that our floating platform launch, landing and crosswind flight models are indeed accurate,” he said. “This means that we can confidently use our simulation tools to test system changes—thousands of simulated flight hours will reduce the risks of our technology before commercial operation.”

Source: 3dnews.ru