Energy and Society. Physics Society Technology and Values Guest Dr. Micha Kilburn

Transcription

1 Energy and Society Physics Society Technology and Values Guest Dr. Micha Kilburn

2 Energy Trends

3 h2p:// As of 2011

4 Side by Side

5 Changes in last decade? Modem speed 56kB- >10MB Smartphones iphone in 2007 h2p://news.netcral.com/ What does this have to do with energy consumpoon?

6 Readings 1. What is the energy cost of a Q status update? a. What are the sources of that energy cost? 2. Current news: How well did nuclear plants withstand Sandy?

7 Looking ahead What will the next decade bring? How will it affect energy consumpoon? How will we keep up with demands? CombinaOon of conservaoon*, new technology, renewable energy resources *room- temperature superconductors?

8 Renewable Energy Resources - Solar Goethe: Energy will do anything that can be done in the world

9 Renewal Energy Resources almost inexhaustible

10 Solar Power how does sunlight turn into electricity Solar power.photovoltaic cells.solar panels.electricity

11 Energy from the Sun comes in the form of Traveling at the speed of light c (3x10 8 m/s)

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13 nm

14 c=λf speed of light E=hf=hc/λ h is planck s constant h= x10-34 Js

15 Spectrum of the Sun. The Sun emits most of its radiation in a wavelength band between 0.1 and 4.0 micrometers (µm). Spectrum of the Earth. The Earth emits most of its radiation in a wavelength band between 0.5 and 30.0 micrometers (µm).

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17 Solar Constant = 2 cal/min.cm 2 Quantum Physics Blackbody Radiation Stefan Boltzmann constant.. Power= Energy/time frequency and wavelength. PhotoElectric Effect Power/Area= Energy/Area.time =εσt 4 ε Is a property of the surface h2p://videos.howstuffworks.com/general- electric/609- ges- photovoltaic- technology- helps- grow- vineyard- video.htm h2p://videos.howstuffworks.com/hsw/6195- energy- solar- energy- video.htm

18 Renewal Energy Resources almost inexhaustible

19 If we have such inexhaustible solar energy ~6000 Times more than all of humanity s energy needs. What is the problem? 1. Not all of the Electromagnetic Spectrum is absorbed 2. Solar cells have to be sensitive to visible part of EM spectrum 3. Efficiency of solar cells 4. Storage of Energy > 2-way grid? 5. Not there when it is cloudy less there in the winter 6. Not there at night 7. Takes energy and $$ to build PV cells 8. Some components of PV cells are toxic Solar cells: Improve efficiency and cost!!!!!!!!!!!!!! Now 15-25% of solar energy is converted into electrical energy In the lab up to 40% efficiency..not yet deployed in market

20 h2p://nuclearfissionary.com

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22 Photovoltaics is the direct conversion of light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity.

23 Photovoltaic modules and arrays produce direct-current (dc) electricity. They can be connected in both series and parallel electrical arrangements to produce any required voltage and current combination.

24 Example. A car wash needs 1200 gallons of warm water a day heated from 50 0 to F How large a solar collector would be needed to do this? The incident solar energy is 1100 Btu/ft 2 The collector is only 50% efficient Look up.. 1 gallon of water= L 3 Density of water= 62.4 lb/l gallons x ft3/gallon= ft ft3 x 62.4lb/ft3= lbs 1 Btu definition.energy needed to raise the temperature of 1lbs of water by 1 0 F lbs x 50 0 F= Btu Btu Btu/1100 Btu/ft 2 = ft 2

25 Renewable Energy Resources II - Hydro Goethe: Energy will do anything that can be done in the world

26 Hydropower, hydraulic power or water power is power that is derived from the force or energy of moving water, which may be harnessed for useful purposes. Prior to the widespread availability of commercial electric power, hydropower was used for irrigation, and operation of various machines, such as watermills, textile machines, sawmills, dock drances, and domestic lifts.

27 Hydro-electricity Today the largest use of hydropower is for the creation of hydroelectricity, which allows low cost energy to be used at long distances from the water source. Hydroelectricity is electricity generated by hydropower, i.e., the production of power through use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy. Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably different output level of the greenhouse gas carbon dioxide (CO2) than fossil fuel powered energy plants. Worldwide, hydroelectricity supplied an estimated 715,000 MWe in This was approximately 19% of the world's electricity (up from 16% in 2003), and accounted for over 63% of electricity from renewable sources.

28 The world's largest is the Three Gorges Dam on the third longest river in the world, the Yangtzi River. Apart from a few countries with an abundance of hydro power, this energy source is normally applied to peak load demand, because it is readily stopped and started. It also provides a high-capacity, low-cost means of energy storage, known as pumped storage. drainage area of 1 million km 2, with an average annual runoff of 451 billion m 3

29 Three Gorges Dam will provide one ninth of China's total power output(the total electric generating capacity of the dam will reach 22,500 MW.)The dam controls flooding, enhances navigation, and provides a vast amount of clean electricity.

30 Hoover Dam on the Colorado River

31 Hoover Dam on the Colorado River Length 1244 L (379 m) Height L (221 m) Base width 660 feet (201m) Crest width 45 L (14 m) Volume Type of spillway Discharge capacity of spillway 3,250,000 cu yd (2,480,000 m 3 ) 2 x controlled drum- gate 400,000 cu L/s (11,000 m 3 /s) ConstrucOon began 1931 Opening date 1936 ConstrucOon cost $49 million

32 Courtesy of BBC: Three Gorges Dam Yangtze river or Chang Jiang

33 The project was begun in 1993 at an official cost of 200bn yuan ($25bn), though unofficial estimates are far higher. When the dam's reservoir reaches its final height of 175m, the five-chamber shiplock will raise boats by as much as 113m.

34 The primary aims of the dam are to alleviate flooding on the Yangtze River and generate power. All 32 turbine generator units are now in operation.

35 July The Three Gorges Dam experienced its largest flood peak this year on Tuesday, with a peak flow of 70,000 cubic meters of water per second

36 At least 1 million people were relocated to make way for the project.

37 Those made homeless by the dam are being moved to new townships. Some say they miss their old homes; others are pleased to have modern facilities.

38 Flood Control Energy Generation Navigation Tourism High investment costs Hydrology dependent (precipitaoon) In some cases, inundaoon of land and wildlife habitat In some cases, loss or modificaoon of fish habitat Fish entrainment or passage restricoon In some cases, changes in reservoir and stream water quality Linked to landslides, erosion Three Gorges Dam is on a seismic fault line