Prof. R. Shanthini Jan 26, 2013 CSP for electricity generation: CSP for electricity generation:...

Prof. R. Shanthini Jan 26, 2013

CSP for electricity generation: CSP for electricity generation: Dish-Stirling system


- A parabolic dish-shaped (e.g., satellite dish) reflector rotates to track the sun.

- The reflector concentrates sun radiation onto a receiver.

- At the receiver, energy is transferred to hydrogen in a closed loop.

- Heated hydrogen (up to 650oC) expands against a piston or turbine producing mechanical power.

http://www.volker-quaschning.de/articles/fundamentals2/index.php



Heated hydrogen (up to 650oC) expands against a piston or turbine producing mechanical power.

- This power is used to run a generator to produce electricity in kilowatts range.

- The power conversion unit is air cooled, so water cooling is not needed.

- Up to 20% efficiency is possible, but costly

http://www.volker-quaschning.de/articles/fundamentals2/index.php


Prof. R. Shanthini Jan 26, 2013 https://www.mtholyoke.edu/~wang30y/csp/ParabolicDish.html


300 MW commercial solar thermal power plant in California


Major solar energy conversion technologies:Major solar energy conversion technologies:

are arrays of cells containing a semiconductor material that converts solar radiation into direct current (DC) electricity.

Solar Photovoltaics (Solar PVs):


PV cell turns sunlight directly into DC electricity.

Total of installed PV was more than 16 GW in 2008.

Solar irradiance

PV module

Charge controller

DC loads AC loads

Inverter

Battery

Stand Alone System

Solar Solar PVsPVs

http://pursolsolar.com/wordpress/wp-content/uploads/2007/05/solarstandalone2.gif


When photons (sunlight) hits the semiconductor, an electron springs up and is attracted to the n-type semiconductor.

This causes more negative electrons in the n-type semiconductor and more positive electrons in the p-type.

Thus a flow of electricity is generated in a process known as the “photovoltaic effect.

Commercially available solar cells achieve solar energy to electricity conversion efficiencies of approximately 15%.

http://global.kyocera.com/solarexpo/solar_power/mechanism.html

Solar Solar PVsPVs


How much electricity can we get from solar roof?

Roof area (assumed) = 10 m2 (all covered with PV cells)

Solar radiation on earth = 2 – 6 kWh/m2/day

(from http://www.nrel.gov/docs/fy03osti/34645.pdf)

Conversion efficiency = 20% (max in the market)

Electricity obtainable = 0.2 x (2 – 6) x 10 kWh/day

= 4 – 12 kWh/day

= 166 – 500 W

= 3 to 8 bulbs of 60 W strength

Solar Solar PVsPVs


Photovoltaic Power for

Rural HomesIn Sri Lanka

Solar Solar PVsPVs


Solar lanternAbout Rs 2500/=

7W CFL, 12V Electronics, 10Wp Panel7Ah MF Battery Backup: 3 to 4 hoursSolar Panel Warrantee: 10 yearsLantern Warrantee: 1 year

Solar Solar PVsPVs


Photovoltaic 'tree'

Solar Solar PVsPVs

http://upload.wikimedia.org/wikipedia/commons/c/ce/Gleisdorf.Solarbaum.jpg


The Pocking Solar Park is a 10 MWp PV solar power plant. - started in August 2005 - completed in March 2006

sheep are now grazing under and around the

57,912 photovoltaic modules

US$87 million

Solar Solar PVsPVs


World's largest PV Power Stations

- Huanghe Hydropower Golmud Solar Park (China, 200 MW)

- Perovo Solar Park (Ukraine, 100 MW),

- Sarnia PV Power Plant (Canada, 97 MW)

- Montalto di Castro PV Power Station (Italy, 84.2 MW)

- Senftenberg Solarpark (Germany, 82 MW)

- Finsterwalde Solar Park (Germany, 80.7 MW)

- Okhotnykovo Solar Park (Ukraine, 80 MW)

(completed in 2010 and 2011)

Solar Solar PVsPVs


Large PV Power Stations in planning / under construction

- Ordos Solar Project (China, 2000 MW)

- Barmer, Bikaner, Jaisalmer and Jodhpur Solar Projects (India, 1000 MW each)

- Calico Solar Energy Project (USA, 563 MW)

- Topaz Solar Farm (USA, 550 MW)

- and more….

Solar Solar PVsPVs


Inorganic Solar Cells

Bulk

2nd GenerationThin-film

Germanium Silicon

Mono-crystalline

Poly-crystalline

Ribbon

Silicon

AmorphousSilicon

NonocrystallineSilicon

3rd GenerationMaterials

CIS

CIGS

CdTe

GaAs

Light absorbing dyes

Solar Solar PVsPVs



Bulk

Germanium Silicon

Mono-crystalline

Poly-crystalline

Ribbon

Silicon

AmorphousSilicon



CIS

CIGS

CdTe

GaAs


CdTe (cadmium telluride) is easier to

deposit and more suitable for large-scale production.

China’s 2000 MW PV plant will use this

technology.

Cd is however toxic.


Solar Solar PVsPVs



Bulk

Germanium Silicon

Mono-crystalline

Poly-crystalline

Ribbon

Silicon

AmorphousSilicon



CIS

CIGS

CdTe

GaAs


GaAs (gallium arsenide) is highly toxic and carcinogenic.

When ground into very fine particles (wafer-polishing

processes), the high surface area enables more

reaction with water releasing some arsine

and/or dissolved arsenic.


Solar Solar PVsPVs



Bulk

Germanium Silicon

Mono-crystalline

Poly-crystalline

Ribbon

Silicon

AmorphousSilicon



CIS

CIGS

CdTe

GaAs


Processing silica (SiO2) to produce silicon is a very high energy process, and it takes over two years for a

conventional solar cell to generate as much energy as was used to make the silicon it contains.

Silicon is produced by reacting carbon (charcoal) and silica at a temperature around 1700 deg C.

And, 1.5 tonnes of CO2 is emitted for each tonne of silicon (about 98% pure) produced.


Solar Solar PVsPVs




Bulk

Germanium Silicon

Mono-crystalline

Poly-crystalline

Ribbon

Silicon

AmorphousSilicon



CIS

CIGS

CdTe

GaAs


Germanium is an “un-substitutable” industrial mineral.

75% of germanium is used in optical fibre systems, infrared optics, solar electrical applications, and other speciality glass uses.

Germanium gives these glasses their desired optical properties.

Germanium use will likely increase with solar-electric power becomes widely available and as optic cables continue to replace traditional copper wire.

Solar Solar PVsPVs


Calculation of United States’ Sustainable Limiting Rate of Germanium Consumption:

Step 1: Virgin material supply limit

The reserve base for germanium in 1999 = 500 Mg

So the virgin material supply limit over the next 50 years

= 500 Mg / 50 years

= 10 Mg/yr

Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9

Solar Solar PVsPVs


Step 2: Allocation of virgin material

Average U.S. population over the next 50 years

= 340 million

Equal allocation of germanium among the average U.S. population gives

(10 Mg/yr) / 340 million

= 29 mg / (person.yr)



Solar Solar PVsPVs


Step 3: Regional “re-captureable” resource base

Worldwide germanium production from recycled material

≈ 25% of the total germanium consumed

Equal allocation of virgin germanium among the average U.S. population therefore becomes 1.25*29 mg / (person.yr)

= 36 mg / (person.yr)

The sustainable limiting rate of germanium consumption in U.S. is thus 36 mg / (person.yr)



Solar Solar PVsPVs


Step 4: Current consumption rate vs. sustainable limiting rate

Germanium consumption in U.S. in 1999 = 28 Mg

Population in U.S. in 1999 = 275 million

So, germanium consumption rate in U.S. in 1999

= 28 Mg / 275 million = 102 mg / (person.yr)

which is about 2.8 times the sustainable limiting rate of germanium consumption in U.S.



Solar Solar PVsPVs


Solar Solar EnergyEnergy

- Solar power systems generate no air pollution during operation.

- Environmental, health, and safety issues involve how they are manufactured, installed, and ultimately disposed of.

- Energy is required to manufacture and install solar components, and any fossil fuels used for this purpose will generate emissions.

- Thus, an important question is how much fossil energy input is required for solar systems.

http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html


- Materials used in some solar systems can create health and safety hazards for workers and anyone else coming into contact with them.

- Manufacturing of PV cells often requires hazardous materials such as arsenic and cadmium.

- Even relatively inert silicon, a major material used in solar cells, can be hazardous to workers if it is breathed in as dust.

- There is an additional-probably very small-danger that hazardous fumes released from PV modules attached to burning homes or buildings could injure fire fighters.




- Large amount of land is required for utility-scale solar power plants (approximately one square kilometer for every 20-60 MW generated).

- Disruption of what might have been pristine property

- Intensive construction activities and having large parabolic solar panels or mirrors taking up acres of land could displace migration routes and habitat of wildlife, flora and fauna.

- New solar installation sites are graded and sprayed with weed control chemicals.

- Humans will be present on a more regular basis driving to the site in vehicles and disposing of trash, etc.




- Solar-thermal plants (like most conventional power plants) also require cooling water, which may be costly or scarce in desert areas.

- Large central power plants are not the only option for generating energy from sunlight.

- Because sunlight is dispersed, small-scale, dispersed applications are a better match to the resource.

- They can take advantage of unused space on the roofs of homes and buildings and in urban and industrial lots.

- And, in solar building designs, the structure itself acts as the collector, so there is no need for any additional space at all.




£5.5 million

CIS Tower, Manchester, England is 118 m skyscraper with a weatherproof cladding (replacing the mosaic tiles) around the tower made up of PV cells (alive & dummy cells).

It generates 21 kW electricity (enough to power 61 average 3-bed houses) and feeds part of it to the national grid.


http://en.wikipedia.org/wiki/Image:CIS_Tower.jpg


Photovoltaic Power for

Rural HomesIn Sri Lanka



Technological status “niche” markets

Average growth 10.6% per year

Total share of global energy mix

0.06% of electricity in 2008

0.54% of electricity in 2035 (potential)

Source: International Energy Outlook 2011



0

50

100

150

200

2008 2015 2020 2025 2030 2035

Year

Ele

ctric

ity g

ener

atio

n

(Ter

awat

t-ho

urs)


Total solar electricity generation projection:Total solar electricity generation projection:

Average growth is 10.6% per year


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

2008 2015 2020 2025 2030 2035

Year

Ele

ctric

ity g

ener

atio

n

RestSolar


World electricity generation projection:World electricity generation projection:


Comparison of Technologies:Comparison of Technologies:

Technology Available energy

(PWh/yr)

Technical potential energy

(PWh/yr)

Current installed

power (GW)

Current electricity generation (TWh/yr)

Hydroelectric 16.5 < 16.5 778 2840

Solar PV 14900 <3000 8.7 11.4

CSP 9250 – 11800

1.05 – 7.8 0.354 0.4


Comparison of Technologies:Comparison of Technologies:

Y. Bravo et al. / Solar Energy 86 (2012) 2811–2825

Prof. R. Shanthini Jan 26, 2013 CSP for electricity generation: CSP for electricity generation:...

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