More than 50 pages longer than the previous edition, Sign Gallery 6 presents recent Signs of the Times competition winners, honorable mentions, and others in this expanded edition of electric ...
Photovoltaic cell and organic, light-emitting diode upgrades equal energy savings.
Thankfully, the world is, in part, waking up to energy-shortage and global-warming threats. The two issues are dreadfully linked because, simply, our current choice of fossil-fuel energy generation produces gigantic amounts of greenhouse gases, which, in turn, lead to global warming. Consider, in 2001, worldwide carbon emissions, caused from burning fossil fuel, surpassed 6.5 billion tons, which, according to Washington DC-based Worldwatch Institute, is a fourfold gain in 50 years.
As developing countries in Asia, Eastern Europe and South America are further modernized, global energy consumption could rise 60% over the next 20 years, which will increase our atmosphere’s CO2 concentration to harmful levels – if current methods of energy generation and consumption continue.
Fossil-fuel combustion resulting from human activities accounts for 75% of carbon emissions; the rest comes, largely, from deforestation, which causes the burning and/or cutting of approximately 34 million acres of trees annually, an area equivalent to the size of Italy.
According to Earth Policy Institute (Washington, DC), the largest share of fossil fuel burning comes from: electricity generation (42%); transportation (24%); industrial processes (20%); and residential and commercial uses (14%). Green-solution technologies, such as solar cells and energy-efficient lighting, may solve nearly half the global, carbon-emission problem.
Photovoltaic cells
Presently, conventional semiconductor-type solar cells and LED luminaires show cost effectiveness in certain applications. Researchers believe organic photovoltaic cells (OPVs) and organic, light-emitting diodes (OLEDs) will soon offer substantial cost savings and exciting new applications.
Photovoltaic-cell (PV) construction is based upon thin semiconductor materials, such as silicon or other optoelectronic compounds, which, when struck by light (photons), release electrons that create direct-current (DC). The material, silicon, is most notably used in electronics to either control (diode structure) or amplify (transistor structure) electronic current.
Currently, PVs use silicon-based photovoltaic material that is both expensive and heavy, and therefore cumbersome for mass-market distribution. However, thinner and lighter OPVs with comparable efficiency and acceptable lifetimes are presently under development.
Traditional silicon PVs operate at 12% efficiency, approximately, and cost roughly $6 per watt output. They’re designed to last more than 25 years. OPVs, presently, endure only a few years with efficiencies ranging near 5%. But, they are lighter, more flexible and may cost less to build.
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