Wind energy
Contents
State of wind energy today (brief)
Today (2017) one of the most efficient methods to extract energy from the wind is by using horizontal axis wind turbines (HAWTs) and scaling them up to very big sizes. In fact HAWTs have become so widespread now that their image is solidly engraved in the public mind.
While much better than fossile sources of energy HAWTs still have some major problems.
- The magnets for the generators in the more modern HAWT designs need lagre amounts of rare earth elements. Mining of these (in china) is associated with bad mining conditions. Mining also presumably leads to production of large amounts of unnaturally fine dust of natural thorium that is easily carried away and spread by the wind. (There are natural beaches with sand rich in thorium but the grains are bigger. Less fine dust that does not go and stay in the lung.) (TODO: do some fact checking on these topics)
- The blades/wings can pose a danger to animals like birds and bats.
- Bad aesthetics: physics and economics dictate the shape little variety is possible. Landscapes may be perceived as becoming more ugly.
Approaches with advanced atomically precise manufacturing technology -- "Energy sails"
With the availability of advanced atomically precise manufacturing one could take very different approaches. One way to replace big monolithic HAWTs would be with "energy sails" made from special medium mover metamaterials.
Unit cells of the such a sail metamaterial might still be of a size that lies in the macro-scale visible to the naked eye. The smaller the unit cells (especially micro-scale or even nanoscale) the more one needs to compensate for gas to solid friction. A certain trick with superlubication (see airmesh) may help but unlike superconductivity superlubrication isn't infinitely friction free. Thus dividing the stream of air into nanoscale portions probably wont be what will be done. Instead the stream of air might be divided into bigger chunks (wild guess: 0.1mm - 10.0mm).
With an active metamaterial sail out of many independently controllable cells the outer rim could be actively driven to suck in air faster in than the wind blows it in. Thereby one could avoid stagnation of air before the sail that normally would leads the air to spill over the edges of the sail. (With conventional wind turbines this is unavoidable). (TODO: Check if that idea isn't too naive.) In general with the pixel like control accuracy it may be possible to keep the air-steam nicely laminar without introducing turbulent flow.
The sails metamaterial would need to integrate mechanochemical (or mechanoelectrical) converters plus sufficient means for energy transport to the sails frame. It may need emulated elasticity. All that should be possible with exclusive use of abundant and easily accessible chemical elements. No need for problematic (but not rare) rare-earth elements.
"Energy sails" made well visible with nice colors that have moving structures well below 1cm would probably pose no threat to birds and bats. Insects could potentially gunk up small moving parts. This might be relevant in the design of the sails. (self cleaning) If some significant non-suppressible sound generation remains (unlikely?) smaller designs might be preferable to avoid hurting human ears and animal ears with a audible low pitched purr.
Going to extremes
Going to global scales one could imagine spanning "energy sail" into the loops of ground tethered aerial meshes. Lighter than air metamaterial meshes that are made pervading good parts of the troposphere. Obviously when going for such large scale geoengineering the theoretical weather effects of super-massive wind-energy-extraction need to be considered. Large scale weather control.
Related
External links
- Wikipedia: Betz's law a limit in efficiency for HAWTs
