Many types of infrastructure elements may be automatically built with variations of the CC technology. For example, a new method of autonomous construction of tall concrete towers has been proposed, which applies to wind turbine towers, bridge pylons, water towers, silos, chimneys, etc. The method employs a set of coordinated vertically climbing robots that carry a special Contour Crafting nozzle assembly and motion control system and a special method of cementitious material delivery system. Implications for wind turbine towers is further elaborated here.
Currently wind turbine towers are constructed using hollow steel segments that are produced at factories, transported to the site at great cost, and assembled using special cranes and specialized crew. The task is a very hazardous one as it is performed at high elevation often under strong wind condition and in tight work envelope involving risks of falling, getting cut between heavy steel segments and being hit by the crane or its load or accessories. Given the current method of tower construction, the tower is the most expensive part of the entire wind turbine assembly which includes the foundation, the tower (about $500K), the nacelle Generator), the yaw and the rotor (blades, the hub and the nose cone).
The large steel sections of the tower have to be transported from the factory to the wind farm for installation. They are often classified as wide load which require special transportation considerations. Furthermore, there is currently a strong motivation to build taller towers that can reach stronger wind elevations. However, the current method of tower construction is limited because it is expensive to build cranes that can reach higher than the current maximum height (85 to 100 meters). Also taller towers require large base segments that will be hard to transport (width limitation of available roads, height limits imposed by overpasses, etc.) Furthermore, large cranes will require wider roads at the wind farm. Currently the cost of road construction especially at hilly wind farms is very significant (about $30M for a wind farm having about 100 installations).
The proposed alternative method of tower construction disclosed here is motivated by the aforementioned high costs associated with steel segment fabrication, transportation, gigantic cranes, labor needed for assembly, and road construction.
The Contour Crafting approach
The proposed approach, showed on this page by an animation, is based on using concrete and automatically constructing towers by means of: a) robotic system that can climb the tower as it is being constructed by a novel construction module, b) the construction module based on Contour Crafting (a large-scale 3D Printing system), and c) a novel material delivery system. The robotic system keeps the construction module that it carries well aligned in such a way that the final tower ends up having near-perfect geometry and orientation with respect to the horizon. A small-scale version of the system has been constructed and the feasibility of the concept has been proven. Future plans of CC Corp includes the development of full-scale CC tower builders.
The major advantages of the new approach are:
- Fully autonomous operation
- Usage of concrete that eliminates factory work on steel segments and difficult transportation
- Safe operation due to elimination of human tasks at risky elevations and windy condition
- Low cost of transportation
- Possibility of building much taller towers