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Outgoing,Likes discovering the world!

Increasing Solar Efficiency by using nanotechnology application

Solar energy has been a crucial research field for many years; unfortunately, due to low conversion efficiency, which the scientists have been trying to deal with, the maximum efficiency has been around 20-30 percent.Recently, advances in nanotechnology is going to lead to a higher efficiency and lower costs which will tremendous impact on solar sector. According to the US Department of Energy’s National Renewable Energy Laboratory(NREL), “the nanotechnology research on solar energy will provide an answer to the efficiency problem, boosting the ability to convert sunlight into power by using less material [1].

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Fig1 .Nanotechnology application on solar cell

Recent study on solar cell from Princeton University showed that by devising a nanostructured “sandwich” of metal and plastic has been increasing triple the efficiency of solar cells. This invention is called plasmodic cavity with subwavelength hole array.It basically consists of a thin strap of plastic sandwiches between the layers.Moreover , Northwestern University introduced a method to increase the efficiency such that it uses carbon-based materials rather than silicon crystals; where the light first enters 100 nm thick leyer with an complex  geometric pattern. These two recent study has been developing by the researches to provide a sustainable for the long term.

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Fig2 . Complex nano-patterning on solar cell

Consequently, the effect on solar industry on energy sector is tremendous. For instance, 8 kwh/day radiation is received in Arizona and Texas which is a very important number.Hence, when the efficiency problem is solved with the ongoing researches, the sector will make a huge profit with lower manufacturing costs [2]. Also, this will be renewable and environmentally friendly which will bring  great and new advantages for everybody.

 

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Source:US Dep. of Energy

References

[1] http://news.nationalgeographic.com/news/energy/2013/04/130429-nanotechnology-solar-energy-efficiency/

[2]http://energy.gov/science-innovation/energy-sources/renewable-energy/solar

 

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Designing Energy for the Future

Thermophotovoltaic, which is known as TPV, was first constructed at MIT in 1956 by Henry Kolm. TPVs convert thermal energy to electrical energy by photons. It basically consists of photovoltaic cell, absorber and thermal emitter. The temperature of the emitter changes from 1000°C to 1400°C . For the operating temperature range, the radiation it recieves is at near infrared and this emitted radiation is converted to free charge carriers by photovoltaic cells. The emitter can absorb sunlight, combustion or nuclear source. In this sense, thermophotovoltaics has provided a great deal in potential fuels.

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Nowadays, there are many research going on especially to increase the efficiency of these devices which is one of the big problem because of efficient operation, large concentrations need to be considered to provide reasonable temperatures. Recently, it has been proved that theoretical efficiency of these devices reach to 40% but because of the many absorbed photons  is not convertible to usable energy their actual efficiency is around 30%. Indeed, photons can’t be absorbed to generate electricity if  their energy is  less than the bandgap of the converter; they are lost or reflected. Hence, the improvements can be made by optimizing the selective emitters in order to have an emission in a narrow wavelength range. In this way, TPVs can deal with a challenge for PVs, by using the entire solar spectrum efficiently.

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Compared to other nonrenewable energy sources, TPV s have less NOx emissions and they are silent. Also, TPVs can be more efficient by enhancing the capability of unabsorbed photons recycling compared to PVs.  On the other hand, the TPVs are more complex and able to lose each energy step, lowering their efficiency. TPVs can also be used with a burner source unlike PVs and they provide on-demand energy. Also, TPVs have more reasonable operation temperatures of 1200 °C which is 0.5 eV whereas PVs have broader temperature ranges around 1800°C which is around 1.1eV. So, some materials used in PV are substantially less efficient and practical for TPVs because the blackbody spectrum is very low at these energies for emitters around that temperature range.

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TPV can be used in many applications in the future such as enabling power source for remote systems, unmanned vehicles, spacecraft, man-portable power sources. Recently, TPVs have been proposed for recreational vehicles  as a hybrid powered system.It also has the ability to use multiple fuels sources which enables better sustainability. Hence, TPV would be a great alternative energy source for the next decade!

Sources

http://iopscience.iop.org/0268-1242/18/5/309;jsessionid=BD0B7B5645755E897A7B836209E21AA5.c1

http://www.interpv.net/tech/tech_view.asp?idx=323&part_code=020080036&page=3

http://www.adsel.ece.vt.edu/research.html

http://en.wikipedia.org/wiki/Thermophotovoltaic

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