Encyclopedia of Computer Science and Technology

216 grid computingoff. By 2000, virtually all new PCs were Energy Star compliant,though many users fail to actually enable the powersavingfeatures.In July 2007 stricter Energy Star specifications for desktopPCs were adopted. Power supplies must now be at least80 percent efficient. Meanwhile, the International EnergyAgency has been promoting an initiative to reduce powerconsumption of idle PCs (and other appliances) to 1 wattor less.Resource ConsumptionComputers consume a variety of resources, starting with theirmanufacturing and packaging. Resource consumption can bereduced by building more compact units and by designingcomponents so they can be more readily stripped and recycledor reused. Adopting reusable storage media (such as rewritableCDs), recycling printer toner cartridges, and changingoffice procedures to minimize the generation of paper documentsare also ways to reduce resource consumption.E-WasteIn recent years the disposal of obsolete computers and otherelectronic equipment (“e-waste”) has been both a growingconcern and a business opportunity. There are manytoxic substances in electronics components, including lead,mercury, and cadmium. Processing e-waste to recover rawmaterials is expensive, so greater emphasis has been placedon disassembling machines and reusing or refurbishingtheir individual components. Meanwhile, many communitieshave banned disposing of e-waste in regular trash, andsome have offered opportunities to drop off e-waste at no orminimal charge. States such as California have also instituteda recycling fee that is collected upon sale of devicessuch as CRT monitors and televisions.Pollution and Greenhouse EmissionsFabrication of computer chips in more than 200 large plantsaround the world involves a variety of toxic chemicals andwaste products. The Silicon Valley alone is home to 29 toxicsites under the EPA’s Superfund Program. The shift of muchof semiconductor and computer component manufacturingto countries such as China that have less strict pollutioncontrols has also exacerbated what has become a globalproblem.Whether through regulation or enlightened self-interest,companies that want to reduce future emissions can useseveral strategies. Manufacturing equipment and processescan be modified so they create fewer toxic substances or atleast keep them from getting into the environment. Nontoxic(or less toxic) materials can be substituted wherepossible—for example, use of ozone-depleting chlorofluorocarbons(CFCs) as cleaning agents has been largely eliminated.Finally, waste can be properly sorted and disposedof, and recycled wherever feasible.Like other major manufacturing sectors, the computerindustry is also faced with the need to reduce the amountof the greenhouse gases (particularly CO 2 ) contributing toglobal warming. This mainly means further reducing theenergy consumption of new PCs. In June 2007 a numberof major players, including Google, Intel, Dell, Hewlett-Packard, Microsoft, and Sun, established the Climate SaversComputing Initiative. Going beyond Energy Star, the programis expected to reduce power consumption equivalentto 54 million tons of greenhouse gases annually—about thesame as that produced by 11 million cars or 20 large coalfiredpower plants.Further ReadingBrandon, John. “Build a Green PC.” ExtremeTech, March 2,2007. Available online. URL: http://www.extremetech.com/article2/0,1697,2097765,00.asp. Accessed August 5, 2007.Cascio, Jamais. Green PC: How to Dispose of Unwanted Tech Equipmentwithout Hassles, and Where to Find Great New EnvironmentallyFriendly Gear. PC World, May 22, 2006. Availableonline. URL: http://www.pcworld.com/article/id,125708/article.html. Accessed August 5, 2007.“Cleaner Computers? Industry to Cut Carbon.” (AP/MSNBC). June12, 2007. Available online. URL: http://www.msnbc.msn.com/id/19203144/. Accessed August 5, 2007.Esty, Daniel, and Andrew S. Winston. Green to Gold: How SmartCompanies Use Environmental Strategy to Innovate, CreateValue, and Build Competitive Advantage. New Haven, Conn.:Yale University Press, 2006.Kuehr, Ruediger, and Eric Williams, eds. Computers and the Environment:Understanding and Managing Their Impacts. Norvell,Mass.: Kluwer Academic Publishers, 2003.Weil, Nancy. “The Realities of Green Computing.” PC World,August 3, 2007. Available online. URL: http://www.pcworld.com/article/id,135509/article.html. Accessed August 5, 2007.grid computingGrid or cluster computing involves the creation of a singlecomputer architecture that consists of many separatecomputers that function much like a single machine. Thecomputers are usually connected using fast networks (seelocal area network). The purpose of the arrangementcan be to provide redundant processing in case of systemfailures, to dynamically balance a fluctuating work load,or to split large computations into many parts that can beperformed simultaneously. This latter approach to “highperformancecomputing” creates the virtual equivalent of avery large and powerful machine (see supercomputer).ArchitectureGrid and cluster architectures often overlap, but the termgrid tends to be applied to a more loosely coordinatedstructure where the computers are dispersed over a widerarea (not a local network). In a grid, the work is usuallydivided into many separate packets that can be processedindependently without the computers having to share data.Each task can be completed and submitted without waitingfor the completion of any other task. Clusters, or the otherhand, more closely couple computers to act more like asingle large machine.The first commercially successful product based on thisarchitecture was the VAXcluster released in the 1980s forDEC VAX minicomputers. These systems implemented parallelprocessing while sharing file systems and peripherals.