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Renewable Energy: An Overview - The Greenhouse Effect

Ninety-three million miles away, the sun blazes energy toward Earth. When this energy reaches Earth, the energy transmitted in short wave-lengths (visible light, ultraviolet, etc.) penetrates our atmosphere and strikes the Earth's surface. Energy in long wavelengths (such as infrared, thermal radiation or heat) is absorbed by carbon dioxide and other gases in the atmosphere. When penetrating short wavelengths strike Earth, they are converted into long wavelengths (in the form of heat radiation) and reflected back toward space. Some thermal radiation escapes, but most of it remains trapped inside our atmosphere. These long waves build up and keep Earth warm. This phenomenon, known as the greenhouse effect, enables life to flourish on Earth.

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Its future effects are also the subject of much discussion.As carbon dioxide and certain other gases increase in the atmosphere, more and more of the heat that should escape and radiate into space remains trapped. This trapped heat is the subject of debate within the scientific community. Scientists, lined up on each side of the issue disagree as to whether this heat may cause a rise in global temperatures.

According to the late Carl Sagan, a world-renowned environmental author, the typical global temperature difference between an ice age and an interglacial period is three to six degrees Celsius (5 degrees to 11 degree Fahrenheit). Sagan theorized that if global temperatures were to rise three to six degrees C, water would become warmer and expand, melt polar ice caps and raise sea levels. Under these conditions, many islands would disappear and the oceans would flood such coastal cities as New York, Los Angles and Tokyo. Just a three-foot rise in sea level would triple the size of San Francisco Bay.

Global warming may change precipitation patterns as well. Rainfall could decrease in some areas, causing water shortages and failing crops, while increasing in other areas with attendant flooding and soil erosion. Plants and animals that do not adapt quickly to the changing environment could become endangered species.

Some scientists, however, believe that an increase in global temperature could result in increased crop yields. Higher carbon dioxide levels associated with global warming could be beneficial for plants. If carbon dioxide levels doubled, it is theorized that plants could improve productivity by as much as one-third. Some evidence shows that a rise in carbon dioxide could increase a plant's optimal temperature and allow plants to thrive in warmer temperatures.

Those that subscribe to the greenhouse theory and global warming believe the primary cause of global warming is high emissions of carbon dioxide from industrial processes and the burning of fossil fuels. The U.S. is the world's largest carbon dioxide emitter. The greatest amount of carbon dioxide emitted comes from burning oil, coal and natural gas to produce the electricity that maintains the American standard of living. Transportation is the second largest contributor to the problem. Each car in the United State emits more carbon dioxide per year than the weight of the car.

Some models used by scientists support the theory that an increase in atmospheric carbon dioxide produces global warming. Scientists have been making attempts to measure any difference in global temperature. Researchers at NASA as well as other scientists believe there has been a 0.5 degree C (0.9 degree F) increase in the average global temperature over the last 100 years. Other scientists remain unconvinced. Researchers using the TIROS-N weather satellite to measure the temperature of the lower portions of the atmosphere during the 1980s did not find any detectable warming.

Despite the controversy over whether the global temperature is rising, the greenhouse effect is a well-established theory in atmospheric science. For example, Venus has a dense carbon dioxide atmosphere that could account for its surface temperatures of 426 degrees C (800 degrees F). Mars, with a thin carbon dioxide atmosphere, has an average temperature of -53 degrees C (-63 degrees F). This temperature difference, however, may also be partially explained by the distance of these planets from the sun.

APS STAR Center

 

APS STAR Center redeployed
(December 2011, text provided by APS)

For the last 25 years, the Solar Test and Research (STAR) Center is where Arizona Public Service has worked with manufacturers, universities and government labs to propel technological advancements in converting solar energy into electricity. The goal? To find technologies that would allow solar energy to become a viable resource option for customers.

Success on that front means the STAR Center takes on a new role.

Personnel and focus have transitioned from technology research to solar operations and maintenance. The chief focus is to provide cost-effective support to ensure optimal system production and research the long-term reliability of our solar investments.

Today, more than 21,500 megawatts of solar have been developed globally, with APS having more than 500 megawatts either online or in development. Manufacturers the world over produce roof-integrated tiles; mono- or poly-crystalline photovoltaic panels; solar box ovens; evacuated tube collectors and glazed flat plate collectors; hybrid solar-thermal systems; hybrid solar lighting systems; solar pumps, fans, and switchable windows; mirrors and tracking systems used in trough/parabolic mirror concentrators; and thermal storage systems. And while listing innovations, I’d be remiss not to mention the increasing deployment of passive solar design – well-known to historians and architects, but never studied on site.

This technological cornucopia has overflowed since the STAR Center opened in 1985, and innovation will doubtless continue.

Now, APS is looking to find solutions to the next set of challenges associated with renewable energy. Namely, how the intermittency from solar and wind resources affects APS’s ability to provide reliable and affordable electricity to customers.

So, while the STAR Center will no longer be open to testing and research of new solar technologies, the solar installations currently in place will remain in operation. A majority of the solar panels at STAR will continue to operate and provide clean energy to customers on the APS grid. Those panels that were removed were re-deployed to other solar projects or returned to the manufacturers.

Further, the STAR Center is now also serving as a working laboratory for those learning to install solar electric systems – or for installation companies who are pursuing continuing education opportunities. Though its mission has changed, APS STAR Center will enjoy a long future of service to APS customers and the solar industry.

Contributed by Renee Guillory, DE Partnership Manager, Arizona Public Service

 

     

Past and Present Research

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Dish/Stirling

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High-concentration PV

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PV Test Rig

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80 kW PV Power Plant

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Inverter Testing

 

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