http://en.wikipedia.org/wiki/Betz%27_law
http://www.windpower.org/en/tour/wres/betz.htm
states that it is not possible to capture more than 16/27 -which is roughly equal to 59.3%- of the wind blowing through a wind turbine kinetic energy.
I have read in
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0471489972.html
that modern wind turbines do achieve peak efficiency rates higher than 50-53%, close to the limit fixed by physics. Does anyone know of a similar physical ceiling for solar-derived energy?
Prospects for photovoltaic efficiency enhancement using low-dimensional structures Martin A Green 2000 Nanotechnology 11 401-405 doi:10.1088/0957-4484/11/4/342 Abstract. The use of photovoltaic solar cells provides an elegant way of converting sunlight to electricity. The photovoltaic industry is currently growing very rapidly, at a compounded rate of about 30% each year. Energy conversion efficiency is a key parameter with this technology since it directly impacts both material and deployment costs. The performance of the traditional bulk semiconductor solar cell is limited to about 33% while thermodynamic limits on the conversion of sunlight to electricity are much higher, at 93%. Low-dimensional structures appear capable of allowing much of this gap to be bridged. These structures allow increased flexibility with traditional efficiency enhancement approaches such as those based on `stacked' or tandem cells, which double efficiency limits to 68%. Perhaps more interestingly, they offer scope for completely new device concepts such as those relying on excitations between multiple energy bands and improved `hot-carrier' cells, that offer scope for similarly high performance.
Martin A Green 2000 Nanotechnology 11 401-405 doi:10.1088/0957-4484/11/4/342
Abstract. The use of photovoltaic solar cells provides an elegant way of converting sunlight to electricity. The photovoltaic industry is currently growing very rapidly, at a compounded rate of about 30% each year. Energy conversion efficiency is a key parameter with this technology since it directly impacts both material and deployment costs. The performance of the traditional bulk semiconductor solar cell is limited to about 33% while thermodynamic limits on the conversion of sunlight to electricity are much higher, at 93%. Low-dimensional structures appear capable of allowing much of this gap to be bridged. These structures allow increased flexibility with traditional efficiency enhancement approaches such as those based on `stacked' or tandem cells, which double efficiency limits to 68%. Perhaps more interestingly, they offer scope for completely new device concepts such as those relying on excitations between multiple energy bands and improved `hot-carrier' cells, that offer scope for similarly high performance.
google on "limits to photovoltaic efficiency" has many links. There are mentions of a "Shockley Queisser" framework for maximum efficiency.
