Gigantic Wind Sail Generator Proposed

I thought about this problem for a long time and came to the conclusion that a different method was needed to collect more power from the wind. The idea I have is a complete departure from the traditional rotating propeller method.  Instead of a stationary wind mill, I imagine a very large wind sail held high in the atmosphere by kites and perhaps helium filled balloons. I think the sail could use very strong but light weight materials and have a wind collection area equal to several football fields. The large wind collection area of such a sail might be equivalent to several hundred wind turbines.
The sail would be connected to a light weight but very strong rope. The rope would be attached to a spool that in turn would be connected to a gear box and generator. The heavy mechanical assembly would be securely anchored to the ground. The force of the wind would pull on the rope and the spool would deploy the rope at a given  rate which is  based on the wind speed. The movement and forces of the pulling rope would spin the generator to convert the mechanical energy into electrical energy. The huge sail might be attached to 10 or 20 miles of rope.
When the sail reached the end of the rope, control lines connected to the sail would collapse most of the sail’s wind collection area. A second identical sail system, attached to the other end of the same rope, would then unfurl another sail and would start its outward pulling cycle. That cycle would pull in the first collapsed sail. To prevent entanglement, the two sails might be separated by several miles. The push-pull action of the two sails would provide a constant flow of power.
Now, imagine each sail to have a million square feet of wind collection area. Assuming an efficiency of 30% and a wind speed of 35 miles an hour, such a wind generator would produce about 70 Megawatts of electricity. Assuming the average home needs about 2,000 watts, the wind sail would be able to provide power to 35,000 homes.
I think the technology exists to make sails with areas measured in square miles. A one square mile sail would be able to produce 2000 Megawatts of electricity in a 35 mph wind. That is enough power for about one million average size homes, enough power for a large city. Then, if the wind were to gust up to 50 mph, the same sail would crank out almost 6,000 Megawatts.
I admit that my idea is still rather rough and preliminary. The concept would need a lot of work to get a practical system developed. A lot more time would be needed to address the issues of keeping the sail from spinning and figuring out ways to collapse the sail at the end of its pulling cycle. But, overall I think it would work. What do you think?

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