For Florian Bauer, co-CEO and chief technology officer of Kitekraft, a Munich-based company that develops flying wind turbine power systems, tackling climate change is a personal matter.
“It all started during my school days when I read Al Gore’s book and saw his documentary ‘An Inconvenient Truth’. This sparked me and prompted my decision to study renewable energy because I felt I could help solve problems by becoming an engineer,” he says. THAT IS in video interviews.
Currently, Bauer, together with André Frirdich, Christoph Drexler, and Max Isensee, are shifting the direction of renewable wind energy through Kitekraft. The company is building a flying wind power plant that includes a tethered electric plane called a kite. The kite has an onboard wind turbine and flies in the shape of a figure eight to generate electrical energy from the wind.
Although flying wind turbine technology is still in its infancy, several companies around the world have taken the initiative to explore airborne wind energy and flying power generation.
Green signal for wind power
With net zero emissions in sight, the International Energy Association (IEA) stated that nearly two-thirds global power generation needs to be renewed by 2030 to achieve the Paris Agreement goals of 2050. Furthermore, wind energy is expected to grow 11-fold by 2050, and it will undoubtedly play a key role in future electricity production.
According to the International Renewable Energy Agency (IRENA), the global installed capacity of onshore and offshore wind farms has increased nearly 100-fold in the last 20 years, rising from 7.5 GW in 1997 to 743 GW in 2020, with 93 GW of new capacity. installed in 2020 only — 53 percent year-over-year increase.
The expansion, accelerated by increasing demand for cleaner energy sources, has led to a reduction in wind power costs, which have fallen by about 40 percent in the last decade and are likely to continue to fall.
Reducing costs can make renewable energy more accessible. This is where the power of the kite comes into play.
Harnessing sustainable energy
But what exactly is a kite-powered system, and how does it generate energy?
Kite powered system generally consists of kite with rotor, mooring and earth station. As the kite flies through the air, the rotor rotates, harvesting wind energy, while the mooring that attaches the kite to the ground station transmits electricity to the ground. Earth stations, in turn, store the energy in batteries or feed it into the grid.
“From an engineering point of view, it’s very interesting. You can combine aerodynamics, electrical engineering, electronic control, software engineering and so on. It’s also an interesting business case,” Bauer said.
Unlike fixed wind turbine towers which require concrete and steel structures, kite-based systems have lightweight moorings and small ground stations, requiring 90 percent less material. “The benefits come from that,” Bauer said.
This is illustrated in a study by Airborne Wind Europe — who found that a 50 megawatt kite farm would use 913 metric tons of material over a 20 year life span, compared to 2,868 metric tons for a typical wind tower farm.
Kitekraft kites are mainly made of aluminum, which is easy to recycle. In contrast, materials normally used in conventional wind turbines, such as steel and carbon fiber reinforced plastics or glass, are difficult to recycle. Although Kitecraft’s rotors are made of carbon fiber, their small size makes recycling the blades easier.
“As a result, it is easier to manufacture and transport, and has a much less carbon footprint. That is one of the problems facing the wind industry today. Steel is quite energy-intensive to manufacture and emits carbon. The price of concrete and steel is very high. also high,” explains Bauer. “We use 10 times less material than conventional wind turbines to get the same unit of energy.”
Rethinking kites
Kitekraft kites are equipped with eight motors that drive the device during takeoff and landing. They are then used as generators during flight. The power electronics control unit stabilizes the kite and generates power efficiently.
“Basically, a kite is a tethered multicopter,” Bauer said. The figure eight pattern made by the kite depicts the most efficient part of a conventional wind turbine. “The blade tips generate most of the energy from the wind.” Wind energy can be generated at relatively low installed capacities, starting from 100 kilowatts.
The company conducted a successful autonomous flight test last year, which it described as a “major milestone towards our first 100kW product.”
Although the kite is still in the prototype stage, it could eventually become a boon for remote areas by bringing renewable energy to those who live off the grid. In addition, kites can come to the rescue in places where it is not possible to erect large wind turbines.
Considering all the advantages of a kite-powered system, there seems to be no reason to build a conventional wind turbine.
However, “it’s much more difficult to make a kite”, says Bauer. “Comparatively speaking, a wind turbine is much simpler — it’s just a tower. One needs to understand the whole technology for making kites. Many of our competitors have been trying to solve the problem for years. Overall, there are some technological and commercial hurdles.”
But will it take off?
“We are talking to a lot of potential customers who expect us to prove reliability and efficiency. What we love is the fact that people are aware of the benefits and cost-effectiveness. It also helps that visibility is low, making it almost invisible,” he said. This can help the community against wind turbines because they consider it an eyesore.
By next year, Baur hopes to solve the problem of autonomy by setting up actuators and sensors. “We also want to reduce software redundancy so we don’t have a single point of failure,” he said. In addition, the technology is also more suitable for storm-prone areas, as the kite can be lowered to the ground rather than risking damage from strong winds.
But, of course, upgrading it is not easy. While the smaller kites are cheaper and easier to deploy and deploy, they will not operate efficiently at altitudes of 984 feet (300 meters) or more, where winds are often the strongest. Developing a larger kite with greater power has risks that need to be carefully calculated.
“Our market entry product is a 100 kilowatt kite with a 33 foot (10 meter) wingspan, which we expect to be delivered by 2024. If all goes well, we will increase it. The next kite will have a power of 500 kilowatts with a wingspan of 65 feet (20 meters). Doubling the wings doesn’t just double the power — on the contrary, you get five times more,” he says.
“The possibilities we see are kite farms, such as wind farms. It can be offshore and on land,” he said. To use it offshore, all you need is an earth station, like a buoy. The kite can be lowered if the wind is too strong. “We can also use it on micro-networks in areas like deserts,” Bauer added.
It remains unclear how widespread the use of kite-based wind power is. However, once engineers solve the engineering and computational problems that keep kites from being widely used, wind energy in the air could be the answer to electrify the future.