unused stuff on turbine power
%
%  \begin{quotation}
%Power output in kilowatts = k x Cp x 1/2 x p x A x Vcubed
%
%k is the constant 0.000133 to yield power in kilowatts; Cp is the
%power coefficient of the turbine, never more than 0.59 and typically
%0.25 to 0.45; p is the air density at your site in pounds per cubic
%foot; A is the swept area of your rotor (usually you use pi x radius
%squared for horizontal axis turbines); V is the wind speed (by far the
%most important variable because of the cube)
%\begin{csmr}
%  B. Clark Howard,
%  World’s Largest Wind Turbines: Is Bigger Always Better?
%  National Geographic,
%  July 20, 2012,
%  \url{www.nationalgeographic.com/environment/great-energy-challenge/2012/worlds-largest-wind-turbines-is-bigger-always-better/}
%\access{April 25, 2019}.    
%\end{csmr}
%\end{quotation}
%
%  \url{www.nytimes.com/interactive/2019/04/11/magazine/climate-change-exxon-renewable-energy.html}
%
%  How Big Business Is Hedging Against the Apocalypse,
%By JESSE BARRON	APRIL 11, 2019
%  
%  He [Jeremy Grantham] explained how a turbine’s efficiency increased
%  exponentially with   the length of its blades.
%
%  \begin{quotation}
%  The study noted that over the past 30 years, wind turbines have more
%  than quadrupled in size. ``With each doubling of wind-turbine
%  manufacturing over time, the Swiss researchers found, the global
%  warming potential per kilowatt-hour of electricity dropped 14
%  percent,'' writes Markovitz.
%
%\end{quotation}
%
%  So the global warming \emph{cost} is decreasing exponentially.
%  That's the carbon footprint of the manufacture.
%  
%Also see
% \url{news.nationalgeographic.com/news/energy/2012/07/120720-bigger-wind-turbines-greener-study-says/}
%
%
%\url{https://www.wind-watch.org/faq-size.php}
%  
%  The widely used GE 1.5-megawatt model, for example, consists of
%  116-ft blades atop a 212-ft tower for a total height of 328
%  feet. The blades sweep a vertical airspace of just under an acre.
%
%The 1.8-megawatt Vestas V90 from Denmark has 148-ft blades (sweeping
%more than 1.5 acres) on a 262-ft tower, totaling 410 feet.
%
%Another model being seen more in the U.S. is the 2-megawatt Gamesa G87
%from Spain, with 143-ft blades (just under 1.5 acres) on a 256-ft
%tower, totaling 399 feet.
%