Those who have no(greatness of) mind, will not acquire the joy of saying in the world, "We have exercised liberality".[Thirukkural 598]
Wind Energy ... This too is a form of Solar Energy and of all the solar spectrum this one specifically uses the Infra Red Radiation part of it to enable itself. Wind is an essential part of our climate which is changing drastically today due to several factors however the fundamental driving factor for wind is the difference in air pressure between two points caused due to the direct impact of local temperature. Normally, if you have a higher temperature area wherein the air gets heated and rises up creating low pressure, the air from nearby areas having lower temperature or high pressure comparatively tries to balance that vacated space by warm air and in compensating as such gives rise to what we call as wind.
The biggest challenge with wind is the consistency ... How can one ensure that wind flows in a specific area, in a specific direction and at a speed so that the energy can be harnessed from it. Even though we have an elaborate field of engineering dedicated to it yet this wind harnessing solution is rather old.
A Bit of History ... from the ThirdPlanetWind portal ...
The earliest known wind powered grain mills and water pumps were used by the Persians in A.D. 500-900 and by the Chinese in A.D. 1200.
The first windmill manufactured in the United States was designed by Daniel Halladay, who began inventing windmills in 1854 in his Connecticut machine shop. The windmill was hugely successful as a means of pumping water on farms and ranches in the expanding western frontier, so much so that Halladay moved his operation to Illinois.
The first electricity-generating wind turbine was invented in 1888 in Cleveland, Ohio by Charles F. Brush. The turbine’s diameter was 17 meters (50 feet), it had 144 rotor blades made of cedar wood, and it generated about 12 kilowatts (kW) of power.
Coming back to the challenge that we were discussing earlier what are the possible options that we have developed to bring about a consistency in level of energy extracted from this inconsistent source of energy ? The basic necessity for installing a wind farm today starts with what we call as a wind map. Wind Map is basically used to chart out a terrain's wind behavior over a period of time which spans a year at least. This map gives us a lot of information in terms of wind speed range over a particular terrain which can be averaged out to assess the feasibility of turbine installation measured at a specific altitude, the pressure conditions, wind behavior over the days based on season, wind direction etc. The wind maps once charted and verified are used to deploy very specific type of turbines which would be ideal for those conditions. These turbines need to rotate at a specific speed in general to deliver power output. And they all come with mechanism to control both the yaw[blade adjustment] and pitch[turbine rotation].
Sample Wind map from https://eurocodeapplied.com/design/en1991/wind-peak-velocity-pressure-uk
You might be thinking what-if the wind turns in to a gale or a storm or hurricane ? The wind turbines and the blades driving these horizontal turbines are developed in such a way that they can always harness the varying speed of the wind by changing the angle of attack into the wind, something like an airplane does when it wants to reduce the resistance while climbing up and increase the air resistance when coming to halt. It must be evident to you by now that these blades are developed to perform against the wind resistance to extract energy and are aerodynamically improvised to that purpose. In addition to that, we also have brakes in the turbines which are meant to handle the over spin or excessive speed of rotation of the turbine blades in the gale or storm like situations as that might harm the overall system and even lead to crash.
There is a term I used earlier "Horizontal Turbines" ... Well yes, its true we do have "Vertical Turbines" as well and by definition the Horizontal and Vertical refers to the axis about which the blades of these turbines move with respect to Earth or let's say the wind.
VAWT vs HAWT as per https://www.energy.gov/eere/wind/articles/vertical-axis-wind-turbines-could-reduce-offshore-wind-energy-costs
Vertical Turbines have a lot of advantage over horizontal turbines where the setup is needed to be catered for large wind farms and in turn greater yield of energy is required and exactly the opposite till date in general on land it is assumed that the vertical turbines are more suitable for low to moderate wind speeds plugged to smaller sized generators.
These concepts of Wind Energy extraction have even translated to Ocean Current Energy Extraction mode as well in various places where the idea is to have turbines with blade maintained under-water in wake of the ocean current which would result into net electricity production.
Nevertheless this energy source remains erratic or rather inconsistent to take place of the technology today which drives the base load, be it solar or wind, if we intend to have a consistent power supply at the end of the day we need to maintain an elaborate measure of saving excess energy in some form so that it can be utilized or compensated when the generation is not available and again that's the reason we end up getting hooked to the grid running based load on non-renewable sources of energy mostly.
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