Energy. on this world and elsewhere. Instructor: Gordon D. Cates Office: Physics 106a, Phone: (434)

Transcription

1 Energy on this world and elsewhere Instructor: Gordon D. Cates Office: Physics 106a, Phone: (434) Course web site available at click on classes and find Physics or at Lecture #17 March 30, 2017

2 Announcements Midterm/super quiz one week from today Info will be up shortly Review session Monday evening

3 Solar Energy

4 Two approaches to generation of electricity from solar energy Solar thermal or Concentrated Solar Power(CSP) Photovoltaics (PV)

5 U.S. Concentrated Solar Power (CSP) electricity installed capacity and generation

6 U.S. utility-scale solar electricity capacity: operating and in the pipeline

7 From the Solar Energy Industries Association

8 From the Solar Energy Industries Association

9 From the Solar Energy Industries Association the changing face of capacity additions

10 From the Solar Energy Industries Association pricing for photovoltaics

11 From the Solar Energy Industries Association big projects

12 The concept of intensity In the context of sunlight: Intensity of sunlight = Incident power of sunlight area over which it falls

13 Intensity of sunlight hitting the earth Above the atmosphere: about 1.4 kw/m2 - This is for a surface FACING the sun. On the Earth s surface: about 1.0 kw/m2 Averaged over day and night, all the seasons, for the 48 contiguous states in the U.S.: around 200 W/m 2

14 Area needed to generate electricity using solar power Power = efficiency x Intensity x Area Area = Power efficiency x Intensity

15 Area needed to generate electricity using solar power 83.4 mi. x 83.4 mi., area needed to produce (on average) all electricity currently used (assuming 200 W/m 2 ).

16 Area needed to generate electricity using solar power 83.4 mi. x 83.4 mi., area needed to produce (on average) all electricity currently used (assuming 200 W/m 2 ). 118 mi. x 118 mi. (twice the above mentioned land area).

17 Area needed to generate electricity using solar power 441 million acres devoted to cropland (for comparison) mi. x 83.4 mi., area needed to produce (on average) all electricity currently used (assuming 200 W/m 2 ). 118 mi. x 118 mi. (twice the above mentioned land area).

18 So what efficiency am I assuming? 441 million acres devoted to cropland (for comparison) mi. x 83.4 mi., area needed to produce (on average) all electricity currently used (assuming 200 W/m 2). 118 mi. x 118 mi. (twice the above mentioned land area). Area = Power efficiency x Intensity Efficiency = Power area x Intensity I ve suggested we use 200 W/m 2 for intensity, and the area I give on my slide is (83.4 mi) 2, so what should we use for power?

19 What is the average power? To get this, let s find the total energy used over a year, and divide by the time over which it is used

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23 Area needed to generate electricity using solar power assuming 12.9% efficiency and 200 W/m million acres devoted to cropland (for comparison) mi. x 83.4 mi., area needed to produce (on average) all electricity currently used (assuming 200 W/m 2 ). 118 mi. x 118 mi. (twice the above mentioned land area).

24 Solar thermal generation of electricity

25 Types of Solar Thermal Parabolic Trough - Most existing facilities, and currently approved facilities in California are of this variety. Solar-tracking dish-based collectors with Sterling Engines This is the SES design, and their are currently 1 or 2 proposed large-scale facilities in California. Power-tower design. - Several have been built, but in the tens of Megawatt range.

26 The Solar Power Tower Design Multiple mirrors called heliostats track the sun and reflect light onto a central collector. Temperatures are so high that molten salt is used as the liquid that get heated. The molten salt, in turn, is used to produce steam that drives turbines to make electricity. The molten salt stores heat so well that the plant can produce electricity for several days without sunlight.

27 Solar Two - 10 MW demonstration project

28 Solar Two - 10 MW demonstration project This system is no longer in operation for the production of electricity.

29 20 Megawatt System near Seville Spain

30 Solar Two - 10 MW demonstration project

31 Solar Thermal The Ivanpah Solar Plant: 377 MW facility nearing completion in the Mojave desert in California.

32 Solar Thermal or Concentrated Solar Power (CSP) The Ivanpah Solar Plant: 377 MW facility nearing completion in the Mojave desert in California. Supposed to deliver 970 GW-hours to various power companies This would represent an average power of GW, indicating 29% of nameplate capacity

33 Example of Solar-thermal technology or CSP: the Suncatcher

34 Example of Solar-thermal technology or CSP: the Suncatcher

35 Suncatcher uses a Sterling Engine at the focus of the mirror array

36 Solar thermal, power production using a heat engine where sunlight provides the heat Long (very long) mirrors forming a trough with a parabolic shape focus sunlight onto pipes, typically containing oil. Temperatures of around 400 degrees C are achievable. The efficiency with which sunlight is converted to electricity is around 25%, extremely good compared to economical photovoltaics.

37 A solar thermal plant was constructed by the Luz corporation in California. Shown are examples of the collectors in the Luz Corporations facility. Luz eventually went bankrupt. Investors who subsequently bought the facility, however, are able to sell electricity at a very competitive price.

38 Part of the 350 Megawatt Solar Electric Generating System or SEGS facility in California originally built by Luz

39 Agua Caliente Solar Project - based on PV Yuma County, Arizona 290 MW (nameplate capacity)

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