Re: Energy harvesting kites?

[Jed Rothwell]

I did not enumerate the advantages of these energy harvesting kites.

Actually, they would not be kites at all, but mobile aircraft. You can manufacture them in one place and have them fly elsewhere. They might descend from the sky to deliver hydrogen to a shopping mall or factory. They would combine the energy generation and distribution system in one machine. They would replace most of the electric power distribution network, most large pipelines, and all oil tankers and coal hauling railroads.

There would be a penalty for having the kites travel long distances. The penalty would be in both energy and wear and tear on the equipment. So normally they would operate close to their home bases, but if there were energy shortages in one part of the world because of seasonal variations in wind, the kites could move energy from one place to another. You would probably not want to deploy them over New York City where there are many airports and where people are skittish about large machines hovering in the sky. To supply hydrogen for New York, you would have them hover far out over the Atlantic and land in New Jersey.

The kites would be scalable; they would deliver a little power or a lot, depending on your needs. A small town might have one visit every few months, whereas a large city might have hundreds a day.

The Skypower people want to make units with 1.5 MW of capacity. If you deployed roughly 5 million of these, with 200,000 held in reserve or in maintenance on the ground, they would generate all of the energy needed worldwide, and distribute it wherever it is needed.

If the power was delivered in the form of hydrogen, variation in winds and peak electric power demand would make no difference. Supply would be smoothed out and continuous. Hydrogen would also be good for transportation applications. If the power could be stored up in ultralight high-capacity batteries, this would mean the battery problem is solved and we would have battery powered automobiles and large banks of batteries to smooth out peak demand.

High-altitude hovering aircraft would also be very useful for television broadcasts and cell phone towers. For television they would probably be better than satellites, and much cheaper.

Safety would be an issue. Five million autonomous kites would cause accidents from time to time. Kites would go out of control and crash, or aircraft would collide with them. Stored up hydrogen might explode. They would also be unsightly, and at their home base where they would be taking off and landing all day long they would be noisy. However, many large cities are close to oceans or deserts where the kites could be deployed without bothering anyone and without hurting anyone if they fell. But no energy system is perfect. Even wind turbines cause deaths. Workmen fall from them and are electrocuted. However wind turbines are the safest source of energy yet devised. They are much safer than nuclear power plants, which have killed thousands of people during the mining and preparation of uranium. Modern uranium mines are supposed to be safer, but they are still a threat.

The kites would pollute less than any other energy source except cold fusion. The only pollution would be in the manufacture and disposal of equipment. It would not take much material to construct 5 million light aircraft. Most of the material would be carbon composite, which is not toxic as far as I know. Carbon is available in unlimited amounts.

Some people have objected to building large unsightly ground-based wind turbines close to historic places and wilderness areas. These kites would be so high up in the sky they would probably not be visible, and many of them would be out over the open ocean, as I said.

They would take up practically no space on the ground. They share this attribute with offshore wind turbines.

- Jed