FAQ
Q: How is the power actually produced?
A: As the kite flies across the sky it generates lift exactly like the wing of an airplane. This lift is transferred to the ground by a high strength rope which is wound around the drum of a specially designed winching system. The winch transforms the pull of the rope into electricity. When the entire length of the rope is let out, the kite is flown back towards the ground as the winch reels the rope back onto the drum. Due to the controllability of the kite’s angle of attack, which changes the lift, this process creates positive net power.
Q: How is the kite controlled?
A: Three lines extend from the winch up to the kite, one of which takes most of the force while the other two are used for steering and controlling the kite’s angle of attack. After analyzing an array of sensors that determine the kite’s position and performance, the flight computer adjusts the relative lengths of the steering lines in order to keep the kite flying along a pre-determined path with the optimum amount of lift force.
Q: Will the system pose any danger to airplanes?
A: The initial operating altitude for the system will be less than 90 meters, (about 300 feet) which is an airspace classification within Canada where kites can be flown without additional considerations. In order to ensure visibility, the kite will be highly reflective and, at night, will be illuminated. We are actively coordinating with civil aviation authorities to extend the operational altitude to between 300 and 400 meters (about 1000 feet).
Q: Why do we want to fly so high?
A: Going further up in the air, the wind becomes dramatically stronger and more consistent as the effect of the ground diminishes. (Wind turbines are built on enormous towers for this reason.) Our kite system allows the power of the strong winds at altitude to be harnessed, but without the need for the massive towers and foundations of conventional turbines.
Q: Will I be able to hear it?
A: As the kite flies through the air it produces acoustic vibrations, like any wing, but doesn’t produce any of the ‘thumping’ noise like a conventional turbine. (The ‘thumping’ comes from the blades passing by the tower, an effect that is not present with a kite.) The kite also travels at a lower relative speed than the blade of a wind turbine, further decreasing its acoustic signature.
Q: Will it harm birds or affect their migratory patterns?
A: As previously mentioned the kite will move at a lower speed than a wind turbine blade and is a relatively soft and flexible structure, so it is very unlikely that it will be harmful to birds or other avian life.
Q: What happens when the wind stops?
A: By flying crosswind patterns, the kite can stay aloft even in very light winds. However, if the wind does stop completely, the kite can be pulled back to the ground using the winch. The reeling-in creates effective wind on the kite, allowing it to be flown and controlled normally.
Q: How will the kites be affected by rain and snow?
A: Just like a wind turbine, our system will make power rain or shine, as long as the wind is blowing. The fabric of our kites has a special coating that resists water impregnation and adhesion from light snowfall. If some ice or rime does accumulate, the flexible nature of the kites causes this to be quickly shed.
Q: What happens when there is extreme weather?
A: Coordinating with local weather authorities, extreme weather events such as lightning storms will be monitored and the kite can be landed and stowed until they pass. Due to this ability to be stowed, the system doesn’t need to be over-built to withstand such events, so it can be constructed more economically.
Q: What about launching and landing the kite?
A: An automated process is currently under development in order to allow the kite to be deployed and recovered automatically. This work is being conducted in collaboration with our international research partners. For the first prototype the kite will be launched and landed manually.
Q: Won’t the ropes and the kites wear out?
A: Mechanical wear and UV damage will require these parts of the system to be replaced periodically. Based on currently available technologies we have integrated this expense into our cost of energy calculations which show that the system will be very competitive. We are also working with rope and fabric providers to look for more durable long-term solutions.
Q: Where will these systems be deployed?
A: The Crosswind portable airborne wind generator will be exactly that, portable. For this reason it can be used in applications that are not feasible for conventional wind turbines, such as temporary camps, remote industrial facilities or isolated communities. Whereas a wind turbine of the same capacity would require a large foundation, tower and heavy equipment for erection, Crosswind’s solution can be transported by a variety of options, including helicopter, and can be deployed without any additional equipment. So the answer to the question is really anywhere the wind blows!
Q: What will it cost?
A: Building a small production series of high tech, autonomous, kite flying robots is not necessarily cheap, so the first units will be deployed to areas with high energy costs, such as remote camps or isolated communities who produce their electricity with diesel generators. However, the scalability of the design is excellent and will offer significant advantages in terms of cost of energy for future systems. Due to its ability to access higher altitude winds and the extremely small material requirements of the system, it will be cost competitive with utility scale wind turbines within the decade.
Q: When can I buy one?
A: We plan to offer a 30kW system, specifically designed for integration into diesel powered grids, in the second half of 2012. For more information please contactsales@crosswindpower.ca.
