Jul 02 2018

How efficient are renewable sources of energy?

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Renewable sources of energy, such as solar, wind, geothermal, and hydro, have been on the rise. In 2017, eighteen percent of energy generated in Texas was in the form of solar or wind and a few small towns there, such as Denton, are striving to rely solely on clean energy (1). This raises the question of whether the whole globe will ever be able to switch to complete renewable energy.

A solar panel system on top of Chase Bank Building in Denton, TX. Image from http://o3energy.com/denton.html

Part of this answer will depend on the efficiency of our energy technology. Our current system relies on the use of fossil fuels however, natural gas power plants are only around 42 percent efficient and coal burning plants are approximately 33 percent efficient (2). Because of this lack of efficiency, we burn through much more energy than we actually use. This suggests that if we switch our grid to renewables that we won’t need to produce as much energy as we currently do. However, is this really feasible? How efficient are our current renewable energy sources?

The efficiency of solar PV depends on the materials of the panels; the two most common types are crystalline silicon and thin film cells. Most of these solar cells have an efficiency of nearly 22 percent. More expensive solar cells have a higher efficiency and many types that are still being researched have yet to reach 15 percent efficiency (3).

The efficiency of different types of solar cells over time. From source 3.


Wind power, one of the cheapest forms of energy, provides a bit more hope. Wind energy efficiency averages around 35-45 percent (4). Theoretical limits described by the law of physics suggest a maximum efficiency of approximately 60 percent (5). This shows that there is room for improvement as we begin to draw more power from this source.

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Geothermal power plants produce electricity constantly and are generally more stable sources of energy. Despite their reliability, they are only about 12 percent efficient (6). Their low efficiency is often primarily due to system design in which the geothermal fluid is separated from the steam used to generate power unless additional technology is installed.

In conclusion, our current renewable energy technologies are not highly efficient but this doesn’t mean they aren’t still promising. We have an incredible amount of solar, wind, geothermal, and hydro power penetrating this earth right now and only a small portion of this energy needs to be utilized to power the globe.



  1. Gass, Henry. “Despite Natural Gas Boom, This Texas Town Is Going 100% Renewable.” The Christian Science Monitor, The Christian Science Monitor, 14 June 2018, www.csmonitor.com/Environment/2018/0614/Despite-natural-gas-boom-this-Texas-town-is-going-100-renewable.
  2. Prentiss, Mara Goff. Energy Revolution: the Physics and the Promise of Efficient Technology. The Belknap Press of Harvard University Press, 2015.
  3. Green, Martin A., et al. “Solar Cell Efficiency Tables (Version 51).” Progress in Photovoltaics: Research and Applications, vol. 26, no. 1, Jan. 2018, pp. 3–12., doi:10.1002/pip.2978 .
  4. The Wind Energy Fact SheetThe Wind Energy Fact Sheet, NSW Government, 2010.
  5. Blackwood, Marisa. “Maximum Efficiency of a Wind Turbine.” Undergraduate Journal of Mathematical Modeling: One + Two, vol. 6, no. 2, 2016, doi:10.5038/2326-3652.6.2.4865.
  6. Zarrouk, Sadiq J., and Hyungsul Moon. “Efficiency of Geothermal Power Plants: A Worldwide Review.” Geothermics, vol. 51, 2014, pp. 142–153., doi:10.1016/j.geothermics.2013.11.001.

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