Modern Lifting Kites Could Carry Containers
The history of kites traces back over 1,000 years in China where “wooden birds” capable of flight were built from bamboo and silk. As kite design improved, kites capable of lifting substantial weight appeared. Fisherman learned how to use kites to assist them in catching fish. During the 1860s, a Japanese architect who had designed a temple, built a lifting kite to lift men and materials to higher elevation during the construction phase of that temple. During the latter 19th century, land surveyors used lifting kites to gain an expanded view of the surrounding landscape. The first powered airplane built by the Wright brothers was essentially a modified lifting kite.
Until the very early 1960’s, all kites were built using a frame with either paper or fabric covering. The first frameless or soft kites first appeared during the early 1960’s. Within 20 years, surfboard enthusiasts had adapted the frameless soft kite for propulsion, in the form of a kite-sail, which could easily and quickly be folded into a small and compact package.
Today, mega-scale airborne sails based on frameless soft kite technology can pull ocean going vessels.
Mega-scale Kite Crane
While many small-scale soft kite designs can fly with a single control line, large-scale variations fly using multiple control lines and could have application along many coastal locations. Some regions of the world experience steady wind that blows predominantly in one direction. Winds that blow at high elevation tend to blow more steadily and at much greater speed than surface level winds that blow in gusts. Modern large-scale soft kites can be made from lightweight, high-strength fabric and can exert considerable tensile force along their control lines, perhaps sufficient to transfer containers between ships.
The application of computer-assisted remote control could greatly enhance the kite-based transfer of containers between vessels or transfer of containers between land and a vessel moored offshore. An electric power cable plus telecommunications cable between land and kite could enable crane-kite operations.
The ability to transfer containers between offshore vessel and a land-based terminal could save deep dredging costs and construction of a specialized terminal at locations where containers may only occasionally be transferred between land and sea. At some locations, such operations could save the cost of building an offshore floating terminal.
Solar thermal energy not only causes water to evaporate from the ocean surface, the different rates at with land and sea increase temperature during daylight also causes winds to blow. Winds blowing over the ocean produce waves and greatly increase evaporation. There are several locations along the Pacific coast of South America where residents have installed fences of fine mesh to harvest potable water directly from moisture laden winds. Except that land based fog (or dew) fences are comparatively small. A mega-scale kite flying at a kilometer above ground could suspend over 1,000 square meters of mesh fabric in the windstream.
Such kites may be installed at locations where extreme humid winds blow across an area of land before again blowing over ocean. While suspended in a humid airstream, the mesh fence could deliver 1,000 to 6,000 liters of potable water each hour during the evening an overnight hours. There are geographic locations where changing weather patterns include the combination of increased humidity and a decrease in local rainfall. The installation of mega-scale frameless kites that carry water-harvesting mesh fabric could provide potable water at such locations, to extract a small percentage of moisture from the winds.
While mainly hobbyists work on refining kites and their design, competing interests have been working on the development of helium-filled airships capable of precise heavy lifting. Such airships could be tethered like a kite and with remote and computer assisted control, transfer containers between a vessel moored offshore and a land based terminal.
Tethered airships could also carry mesh fabric that could harvest potable water from humid incoming air, with the tether carrying power and control cables to allow for remote, ground based control over an airborne vessel. However, kites will have no need for helium.
The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.