Illumin Paper
WRIT 340
Prof Martha Townsend
Jenny Yu
May 2, 2014
Yu, 1
A Cooler and Brighter City
Taking advantage of the sun
In the north east where snow is an issue, heated driveways and sidewalks are
implemented, melting away the snow and ice for a safer commute. Taking advantage of the
sunlight available in southern California may be the key to help preserve the environment. Solar
energy is an effective energy source that can be used in many different settings and
environments. Many homes are significantly decreasing their electricity bills by switching to
solar energy and universities are beginning to look into new ways to incorporate solar through
buildings or sidewalks. With more focus on discovering more efficient methods of solar panels,
not only can we can help decrease the burning of fossil fuels and the production of carbon
dioxide gases that harm the environment, but also cool urban infrastructure with sidewalk,
window, and sidewalk alternatives. We can significantly improve the urban infrastructure by
implementing solar and alternative reflective solutions.
Implementing Solar
Solar Rooftops and Windows
As government incentives are a bonus to investing in solar panels, people are switching
over at a speedy pace, lowering their monthly electricity bills and providing their own power.
The semiconductor consists of a panel of many silicon solar cells that generate electric currents.
These photovoltaic panels that harness solar energy are one of the most economical alternative
energy sources, covering rooftops and windows all over the country where sunlight is abundant.
Yu, 2
Solar Sidewalks
Imagine walking to class and stepping on solar panels that help power the lighting in your
next classroom or are used to light the pathway at night time. Solar sidewalks are an innovative
idea and have successfully been implemented at the George Washington University’s Virginia
Science and Technology campus. Even though the university has only installed a 100 square foot
sidewalk, it produces 400 watts which is enough solar energy to power the 450 LED lights that
are underneath it to light up the path at night, and the remaining energy source is channeled to
their nearby Innovation Hall. This project named "The Solar Walk" is created using Onyx Solar
and photovoltaic panels.1 Photovoltaic panels use solar cells to convert solar radiation into
electricity. Figure 1 pictures the weight “The Solar Walk” can withstand, depicting four football
players with an average weight of 200 lbs each.
Figure 1. The solar sidewalk can hold the weight of about 400 kilograms (882 pounds). ¹
Image from: http://mysportsclipart.com/design/sports-clip-art-of-a-american-football-player-byleonid-7161
1
Meehan, Chris. "GWU Introduces World's First PV Sidewalk." Solar Reviews. N.p., 08 Oct. 2013. Web.
Yu, 3
Increasing Solar Efficiency
The issue with solar energy conversion is finding low cost solutions that do not limit the
photovoltaic conversion efficiency. Some solutions include using concentrated sunlight in a
hybrid thermophotovoltaic conversion process which is compatible with the conventional silicon
photovoltaic cells. This process can potentially increase the efficiency of a single-junction
photovoltaic cell from 33% to 73% using low-energy photons.2 Another solution is using the
thermal energy storage of a corn-based bioethanol plant to connect with solar panels to power a
solar-assisted steam generation system with heat storage, improving plant profitability and
energy consumption and lessening the use of fossil fuels.3
2
Boriskina, Svetlana V., and Gang Chen. "Exceeding the Solar Cell Shockley- Queisser Limit via
Thermal Up conversion of Low-energy Photons." Optics Communications 314 (2014): 71-78. Elsevier.
01 Mar. 2014. Web.
3
Brunet, Robert. "Minimization of the Nonrenewable Energy Consumption in Bioethanol Production
Processes Using a Solar-assisted Steam Generation System." Alche Journal 60.2 (2014): 500-06. Wiley
Online Library. 28 Oct. 2013. Web.
Yu, 4
Solar panels have also found to be most efficient when using a different solar cell design.
By formatting the cells into a Lego pattern, light is allowed to bend in a way that boosts solar
efficiency.4 Figure 2a shows the lego pattern of each layer and Figure 2b shows the scattered
absorption of the cross section efficiency for the different metals used and depicts the
significance of metal choices. The metal used for scattering nanoparticle arrays is crucial in
optimizing photocurrent improvements.5 While current solar panels use gold and silver materials
to construct, using enhanced photovoltaic cells made of different materials such as aluminum or
other metals can make solar panels more affordable in the future.
(a)
Figure 2a. "Lego" pattern
Figure 2b. "Lego" metal layers
of a solar panel to efficiently trap
light. ⁹
4
Rogers, James. "Solar Innovations: Sidewalks, Windows, and Legos?" Sierra. N.p., 31 Oct. 2013. Web.
Hylton, N. P. "Loss Mitigation in Plasmonic Solar Cells: Aluminium Nanoparticles for Broadband
Photocurrent Enhancements in GaAs Photodiodes." Nature.com. Nature Publishing Group, 07 Oct. 2013.
Web.
5
Yu, 5
Cooling the Urban Infrastructure
Green Roofs, Cool Buildings, and Cool Pavements
A problem that the urban environment experience is the increased surface temperature of
the rooftops, sides of buildings, and the ground, and the negative impacts on the microclimate of
the immediate surroundings. The Walt Disney Concert Hall is an example of a location with
increased ground temperature in the vicinity of the building. The study of measuring the visual
glares of the building poses possible other alternatives to the thermal impact on the environment.
Due to the many reflective surfaces of the Walt Disney Concert Hall, overheating can occur in
surrounding buildings and even outdoors. The ground surface temperature on a summer day was
averaged at 125 ° F and some curb temperatures to be about 138 ° F.6 Solutions to this effect are
reflective coatings such as highly reflective roofs and highly reflective pavements on urban
environments to lower surface temperatures of the buildings and sidewalks.7 The cool roof and
cool pavement may reflect solar radiation from the pavement however and may cause discomfort
for pedestrians as it raises the human body temperature. Roofs covered with vegetation are an
excellent way to help reduce building heating as green roofs include drainage and insulation.
Figure 3 shows the layers of an example of a green roof.
Figure 3. Green roof system example
Image modified from:
http://www.greenroofs.org/ind
ex.php/about/aboutgreenroofs
6
Schiler, Marc. "Microclimatic Impact: Glare around the Walt Disney Concert Hall." Proceedings of the
Solar World Congress 1 (2005): 511-16. Web.
7
Kondo, Yasushi, Takeshi Ogasawara, and Kunihiro Udoh. "Influence of Radiation Reflected by Cool
Pavement on Thermal Sensation of Pedestrians." Journal of Environmental Engineering 74.637 (2009):
323-30. Web.
Yu, 6
Three types of pavement assess which implementation best stabilizes surface temperature.
Exposed to direct sunlight and shaded areas, the most ideal pavement was found to be made from
open cell concrete blocks filled with vegetation.8 Also by investigating the uses of surface
temperature sensors and data logging samples, fourteen types of reflective coatings were used to
find the optimal coating for thermal performance.9 Figure 4 shows the samples placed on the
modulated platform.
Figure 4. Coatings laid out horizontally and insulated from below.
The results were that the white colored coatings performed better than the aluminum colored
coatings because the aluminum remained hotter over time due to a low infrared emittance. Cool
coatings exhibited the best thermal performance\but also experienced degradation due to
weathering. Applying these coatings could reduce surface temperatures, improve building
comfort, and reduce cooling energy usage.10
Mascaro, Juan J. "Shaded Pavements in the Urban Environment – a Case Study." Taylor and Francis, 21
Mar. 2012. Web.
9
Synnefa, A., M. Santamouris, and I. Livada. "A Study of the Thermal Performance of Reflective
Coatings for the Urban Environment." Solar Energy 80.8 (2006): 968-81. Science Direct. Aug. 2006.
Web.
10
Synnefa, A., M. Santamouris, and I. Livada. "A Study of the Thermal Performance of Reflective
Coatings for the Urban Environment." Solar Energy 80.8 (2006): 968-81. Science Direct. Aug. 2006.
Web.
8
Yu, 7
The future is cool and bright
By implementing these changes, we are able to significantly improve the urban
infrastructure, cooling and protecting the environment. Solar and the other alternative green and
cooling solutions are ideal to developing a newer, cooler, sustainable city.
About the Author:
Jenny Yu was born and raised in Los Angeles and is studying Environmental Engineering.
Yu, 8
Bibliography
1.
Boriskina, Svetlana V., and Gang Chen. "Exceeding the Solar Cell Shockley- Queisser
Limit via Thermal Up-conversion of Low-energy Photons." Optics Communications 314 (2014):
71-78. Elsevier. 01 Mar. 2014. Web.
2.
Brunet, Robert. "Minimization of the Nonrenewable Energy Consumption in
BioethanolProduction Processes Using a Solar-assisted Steam Generation System." Alche
Journal 60.2 (2014): 500-06. Wiley Online Library. 28 Oct. 2013. Web.
3.
Dos Reis, F.S. "A Low Voltage Electronic Ballast Designed For Hybrid Win-Solar Power
Systems." Industrial Electronics, 2007. ISIE 2007. IEEE International Symposium on (2007):
3066-071. Web.
4.
Hylton, N. P. "Loss Mitigation in Plasmonic Solar Cells: Aluminium Nanoparticles for
Broadband Photocurrent Enhancements in GaAs Photodiodes." Nature.com. Nature Publishing
Group, 07 Oct. 2013. Web.
5.
Kondo, Yasushi, Takeshi Ogasawara, and Kunihiro Udoh. "Influence of Radiation
Reflected by Cool Pavement on Thermal Sensation of Pedestrians." Journal of Environmental
Engineering 74.637 (2009): 323-30. Web.
6.
Mascaro, Juan J. "Shaded Pavements in the Urban Environment – a Case Study." Taylor
and Francis, 21 Mar. 2012. Web.
7.
Meehan, Chris. "GWU Introduces World's First PV Sidewalk." Solar Reviews. N.p., 08
Oct. 2013. Web.
8.
Rogers, James. "Solar Innovations: Sidewalks, Windows, and Legos?" Sierra. N.p., 31
Oct. 2013. Web.
9.
Saravanan, S. "Instantaneous Reference Current Scheme Based Power Management
System for a Solar/wind/fuel Cell Fed Hybrid Power Supply." International Journal of Electrical
Power & Energy Systems 55 (2014): 155-70. Feb. 2014. Web.
10. Schiler, Marc. "Microclimatic Impact: Glare around the Walt Disney Concert Hall."
Proceedings of the Solar World Congress 1 (2005): 511-16. Web.
11. Synnefa, A., M. Santamouris, and I. Livada. "A Study of the Thermal Performance of
Reflective Coatings for the Urban Environment." Solar Energy 80.8 (2006): 968-81. Science
Direct. Aug. 2006. Web.
Yu, 9