1 / 36

Discussion points: Robinson Article - PowerPoint PPT Presentation

Discussion points: Robinson Article. General comments? What is the strongest argument? What is the weakest/most suspect? Did it change anyone’s thinking?. There are lots of other sites that you can find to argue with points in Gore’s movie e.g. www.cei.org/pdf/ait/AIT-CEIresponse.ppt ,.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

PowerPoint Slideshow about 'Discussion points: Robinson Article' - lona

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Discussion points:Robinson Article

• What is the strongest argument?

• What is the weakest/most suspect?

• Did it change anyone’s thinking?

There are lots of other sites that you can find to argue with points in Gore’s movie

e.g. www.cei.org/pdf/ait/AIT-CEIresponse.ppt ,

Figures:Robinson Article

Figures:Gore’s version

Figures:Robinson Article

T typical availability of a wind farm is 17-38% for land-based plants and 40-45% for off-shore plants.

An extensive site for Wind

Information!!

http://www.windpower.org/en/tour/wres/euromap.htm

• Power available is roughly:

• P=2.8x10-4 D2 v3 kW (D in m, V in m/s)

• I.e. you get much more power at higher wind speeds with larger turbines

• 3-blade turbines are more efficient than multi-blade, but the latter work at lower wind speeds.

• At higher wind speeds you need to “feather” the blades to avoid overloading the generator and gears.

• Typical power turbines can produce 1 -3.5 MW

Altogether, there are 150,000 windmills operating in the US alone (mainly for water extraction/distribution)

7% efficiency, but work at low wind speeds

According to wikipedia, as of 2006 installed world-wide capacity is 74 GW (same capacity as only 3.5 dams the size of the three-Gorges project in China).

Up to 56 % efficiency with 3 blades, do very little at low wind speeds

Wind range: 3.5m/s to 25m/s

Rated wind speed: 11.5 m/s

GE 2.5MW generator

A useful link demonstrating the design of a basic solar cell may be found at:

http://jas.eng.buffalo.edu/education/pnapp/solarcell/index.html

• There are several different types of solar cells:

• Single crystal Si (NASA): most efficient (up to 30%) and most expensive (have been \$100’s/W, now much lower)

• Amorphous Si: not so efficient (5-10% or so) degrade with use (but improvements have been made), cheap (\$2.5/W)

• Recycled/polycrystalline Si (may be important in the future)

• Isolated atoms have electrons in shells” of well-defined (and distinct) energies.

• When the atoms come together to form a solid, they share electrons and the allowed energies get spread out into “bands”, sometimes with a “gap” in between

Energy

Gap (no available states)

n-type

p-type

Conduction band

Energy

_ _ _ _

Gap

_ _ _ _

Valence band

Position

• Separate p and n-type semiconductors. The lines in the gap represent extra states introduced by impurities in the material.

• n-type semiconductor: extra states from impurities contain electrons at energies just below the conduction band

• p-type has extra (empty) states at energies just above the valence band.

n-type

p-type

Conduction band

Energy

_ _ _ _

Gap

_ _ _ _

Valence band

Position

• When the junction is formed some electrons from the n-type material can “fall” down into the empty states in the p-type material, producing a net negative charge in the p-type and positive charge in the n-type

n-type

p-type

Conduction band

Energy

+

_ _ _ _

Gap

_ _ _ _

_

Valence band

Position

• When the junction is formed some electrons from the n-type material can “fall” down into the empty states in the p-type material, producing a net negative charge in the p-type and positive charge in the n-type

n-type

p-type

Conduction band

Energy

+

_ _ _ _

Gap

_ _ _ _

_

Valence band

Position

• When a light photon with energy greater than the gap is absorbed it creates an electron-hole pair (lifting the electron in energy up to the conduction band, and thereby providing the emf).

• To be effective, you must avoid:

• avoid recombination (electron falling back in to the hole).

• Avoid giving the electron energy too far above the gap

• Minimize resistance in the cell itself

• Maximize absorption

• All these factors amount to minimizing the disorder in the cell material

• Need to absorb the light

• Anti-reflective coating + multiple layers

• Need to get the electrons out into the circuit (low resistance and recombination)

• Low disorder helps, but that is expensive

• Record efficiency of 42.8% was announced in July 2007 (U. Delaware/Dupont).

• Crystalline Si: highest efficiency (typically 15-25%), poorer coverage, bulk material but only the surface contributes, expensive (NASA uses them).

• Amorphous Si: lower efficiency (5-13%)

http://www.nrel.gov/ncpv/pv_manufacturing/cost_capacity.html

Martin Green’s record cell. The grid deflects light into a light trapping structure

100 cm2 silicon

Cell under different

Illumination conidtions

http://www.solarserver.de/wissen/photovoltaik-e.html

http://www.nrel.gov/highperformancepv/

Flood light system for

\$390 (LED’s plus xtal.

cells)

40W systems for

\$250, 15 W for \$120

Typical pattern for crystalline

cells

Battery charges (flexible

Amorphous cells)

Typical patterns for amorphous

cells

http://www.siliconsolar.com/

• Solar Cells

• Need to get the electrons out into the circuit (low resistance and recombination)

• Low disorder helps with both (hence crystal is more efficient than amorphous)

• Crystalline Si: highest efficiency (typically 15-25%), poorer coverage, bulk material but only the surface contributes, expensive (e.g. NASA).

• Amorphous Si: lower efficiency (5-13%), less stable (can degrade when exposed to sunlight).

http://www.iit.edu/~smart/garrear/fuelcells.htm

For more details on these and other types, see also:

http://www.eere.energy.gov/hydrogenandfuelcells/fuelcells/fc_types.html

• 85kW basic module power

• (scalable from 10 to 300kW

• They say) for passenger cars.

• 212 lb (97 kg)

• 284 V 300 A

• Volume 75 liters

• Operates at 80oC

• H2 as the fuel (needs a

• reformer to make use of

• Methanol etc.)

• 300kW used for buses

• Appears to be a molten

• carbonate systme based on

• their description

• Standard line includes units

• of 0.3,1.5 and 3 MW

• Fuel is CH4 (no need for

• external reformer) can also

• use “coal gas”, biogas and

• methanol

• Marketed for high-quality power

• applications (fixed location)

This is a nominal 300kW unit (typically delivers

250kW according to their press releases). Most

of the units installed to date are of this size.

http://www.netl.doe.gov/publications/proceedings/03/dcfcw/dcfcw03.htmlhttp://www.netl.doe.gov/publications/proceedings/03/dcfcw/dcfcw03.html

http://www.netl.doe.gov/publications/proceedings/03/dcfcw/Cooper%202.pdf

• Hhttp://www.netl.doe.gov/publications/proceedings/03/dcfcw/dcfcw03.html2 burns with 02 to make water

• H2 comes from the oceans (lots of it)

• Fuel cells can “burn” it efficiently/cleanly

The Hydrogen Hype

The Realities

• Can’t mine it, it is NOT an energy source

• Why not just use electricity directly?

• Even as a liquid, energy density is low

• Storage and transport are difficult issues

• More dangerous (explosive) than CH4

• No existing infrastructure

Hydrogen Economy

Need lots of research in areas such as:

Production

Transmission/storage

Distribution/end use

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdfhttp://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdfhttp://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdfhttp://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdfhttp://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdfhttp://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf

Hhttp://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf

Al

4 H molecules

in 51264 cage

Storage Possabilities

Weak binding energy -> Low T required

Carbon nanotubes

Porous materials

Zeolites

Physisorbtion

Reversible Hydrides

PdH, LiH, …

Large energy input to release H2

Slow Dynamics

Chemical Reaction

Very large energy input to release H2

Not technologically feasible

Chemisorbtion

H2 trapped in cages or pores

Variation of physical properties

(T or P) to trap/release H2

Encapsulation

MIT web site on photo-production:http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf

http://web.mit.edu/chemistry/dgn/www/research/e_conversion.html

Nature and Physics Today articles:

Nature Vol. 414, p353-358 (2001)

Physics Today, vol 57(12) p39-44 (2004)

DOE report from 2004 is available at:

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/review04/4_science_stevens_04.pdf