###### Alyssa is an 18-year-old who presents to clinic with a concern that her acne has worsened since she started college. She currently is using a benzoyl peroxide 5% wash once a day.
December 22, 2017
###### Case Study #4- PAIN
December 22, 2017

Question
In lecture we discussed “energy-based solar land use efficiency” which had the units of MWh/ac-y of electrical energy delivered from a solar power facility. Energy-based solar land use efficiency is similar to another term “power density factor” which seeks to identify the amount of land required for various energy technologies. The power density of an energy source is the average electricity delivered per of area of land used and is generally reported in units of W/m2. It has been proposed that the power density of an energy source is a fundamental consideration when evaluating the sustainability of an energy source.

In problem 2 we considered a wind farm composed of 25 Siemens direct drive wind turbines each with a rated capacity of 3.2 MW. The rotor diameter is 101 m. The wind turbines each require a plot of land measuring 2d x 3d, where d is the rotor diameter. It is estimated that the wind farm will generate 200 GWh of electricity annually. What is the energy density of the wind farm discussed in problem 2 (W/m2)?
The London Array is world’s largest offshore wind farm (http://www.londonarray.com/the- project-3/). The first phase of the London Array consists with 175 3.6 MW wind turbines covering an area of 100 km2 and is expected to have a capacity factor of 39.3%. What is the energy density of the London Array (W/m2)?