New Recreation Center Challenges Students to Greater Heights ...

New Frontiersthe three partner agencies (Mines/NREL/NCAR) workingon a primary challenge topic will get top priority. Minesresearchers working on other energy-science topics takesecond place. Mines educational programs and otherresearch requiring high performance computing takethird and fourth respectively. Other academic institutionsconducting energy-related research are fifth, and energyrelatedresearch by industry comes in sixth.The cluster, which should be completed in early spring,will occupy a total area of only 80 square feet of denselypacked computer processors. It will be linked to theFront Range GigaPop—a consortium of 16 government,educational and research institutions. With closer linksamong these institutions, GECO may enhance the regionalsynergy among agencies concerned with computationalresearch, while providing a powerful new resource insupport of Mines’ mission in energy science.Opportunities in Solar PowerUntil you check the price tag, the appeal of solar power isalmost irresistible—with modern technologies that enablehomeowners to run their electric meter backwards during theday, an array of solar panels on a sunny roof can provide freeelectricity to that home for decades. But because of the highcost, solar energy only accounts for less than 1 percent of thetotal energy generated in the U.S. and there are good reasonswhy this is the case. Factors like performance, availability,material cost, and the toxicity of the materials used all playa part. Additionally, the ease, cost, and reliability of theprocessing techniques used for manufacturing are partly toblame.However, despite these factors, solar energy is growingrapidly: Demand is at an all-time high, and development isbeing propelled by an increased number of research grants,state and federal government incentives, and investment fromventure capital firms.One of the most promising breakthroughs in solar energyis thin film technology, which researchers at Mines have beenstudying for several years. The current solar cell marketis dominated by bulk or crystalline silicon with an averageefficiency of 14 to 16 percent for commercially available cells.These cells are inherently expensive because of the relativelythick layer of crystalline silicon—about 100 microns—neededto convert sunlight to electricity. In contrast, thin film cellsrequire a layer only five microns thick, thus drasticallydecreasing material costs. The three dominant thin filmtechnologies currently under development are amorphous12 Fall 2007The 25-story CIS Towerin Manchester, UK, isclad in crystalline siliconphotovoltaic cells. As thinfilm technologies mature,applications like this areexpected to become muchmore economical and widespread.silicon, cadmiumtelluride and copperindium galliumdiselenide. Althoughthe latter of thesehas achieved animpressive laboratoryefficiency of 19.5percent, amorphoussilicon is the optionwith greatestproduction capability, though its having laboratory efficiencylevels is about 10 percent.The basic structure of a thin film solar cell is similar to thatof traditional solar cell technologies: there is an absorber layerand two contacts. When photons in sunlight are absorbed,electrons are excited and knocked loose from their atoms.These electrons then flow through a conductor band into thepositively charged side of an electrical circuit, leaving behindan “electron hole” on the original host atoms. These holes arereoccupied by electrons returning to the cell on the negativelycharged side of the circuit. This process of converting light toelectricity is known as the photovoltaic effect.The goal in solar cell development is to find a balancebetween the cost associated with manufacturing and theefficiency. Although thin film technologies are not, for themost part, any more efficient than crystalline silicon, theyhave the potential to be significantly more cost effective. Someof the most promising approaches being explored at Minesare spraying or printing thin film cells; plasma processingapproaches; organic solar cells; the so-called “third generation”cells, such as silicon nanodots and nanowires; incorporatingsolar cells into building materials; tandem amorphous silicon/nanocrystalline silicon cells; and manufacturing cells that canbe laminated onto flexible materials. With the considerablesums of money being channeled into each of these fields,progress has been steady and lower-cost solar cells aremaking their way to market. And given that the cost of utilitygeneratedelectricity is projected to rise, the economicsmay soon swing in favor of photoroltaics, resulting in a rapidexpansion of this most alluring technology.