Google files multiple patent to optimize electricity generation in project Makani through a control schemes for rotors of flying wind turbines.
Google, for years, has been interested in solving one of the most pressing issues of the world to create clean energy. For that pursuit, in 2013, Google acquired Makani Power and since it has been working on flying wind turbines.
Side note: With the acquisition Makani became the firm that Google acquired specifically for its Google X skunkworks.
In March this year, Astro Teller, head of Google X announced flying 84-foot wind turbine in April. This was the full scale model of airborne wind turbine. Before that Google was flying wind turbines of 28 feet in length.
Recently we came across patents filed by Google on project Makani. The patents are describing a method to optimize electricity generation in airborne wind turbines.
I’ll run over the patented method later in today’s post. Before that, first have a bird eye view of the working of energy kite system of project Makani.
How the Project Makani Works
The energy kite system of Makani consist of four parts viz. the flying wind tunnel, a tether, ground station, and a computer.
The flying wind turbine stays on the ground station until the wind is not conducive to power generation. Once the wind becomes conducive, the ground station launches the flying wind turbine in air upto an altitude of 250 meters.
After getting airborne, the rotors of flying wind turbine generate electricity by working in different wind conditions. The generated electricity then, transmitted to the ground station via the tether.
While the wind turbine is airborne, the computer continuously guides it to optimize electricity generation.
You are going to come across terms like rated power output, rated wind speed and threshold point below. Lets get familiarize with these terms first. This will help you to grasp the topic without efforts.
Every kite has a maximum power output that is known as rated power output. The wind speed at which rated power output is reached is known as rated wind speed. And threshold level is a point where electricity generation uses to be at peak.
Makani’s energy kites work in conditions where the wind speed keeps on changing continuously. Though, electricity generation is favored by increase in wind speed as that leads to increase in power output. However, that leads to heat production also.
This limits the operational parameters of an airborne wind turbine as a part of electricity starts getting lost to heat. Thus, to increase efficiency of electricity generation, it’s vital to mitigate the heat production.
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Solution: Power Generation Management
And this is what the patents (1, 2) filed by Google are doing. The patents mention two power control schemes for rotors of airborne wind tunnels. Among the two, the first control scheme prioritizes power generation while the second control scheme prioritizes heat control.
The two control schemes are employed depending upon the power generation states.
Let say, the flying wind turbine (FWT) is in crosswind flight mode and generating electricity less than rated power and the threshold level.
The threshold level is also a point going above which may lead to decrease in efficiency of electricity generation due to heat.
Now if the FWT operates in a state where power generation is below than rated power as well as threshold level, the first control scheme for rotors will be followed. The rotors will be controlled to generate more power in this situation.
And if the FWT operates in a state where the rotors generates more current than the threshold level, the second control scheme – for heat control, will be followed.