Sources: http://www.physicstoday.org/pt/vol-53/iss-11/captions/p29box2.html
CASE STUDY FOR JAVA-
Many industries currently receive their electricity from a central power station and their process heat from a separate onsite boiler. However, increasing numbers are opting to produce both electricity and heat onsite with a combined-heat-and-power (CHP) system, also called cogeneration. CHP, largely in the industrial sector, now accounts for nearly 10% of
Conventional power plants typically have efficiencies of just 30% and thus discard 70% of the input energy as waste heat. By contrast, the natural-gas-fired combustion turbines used in the industrial sector have efficiencies that have risen from less than 20% in the mid-1970s to more than 40% today. Their system efficiencies are above 85% when the waste heat is used for industrial processes or for plant heating and cooling.
Considerable savings in energy could result from wider deployment of CHP systems,15,16 as illustrated in the figure above. As seen for the separate heat and power (SHP) system in the left-hand panel, US manufacturers in 1994 used 2.7 Q in electricity supplied from power stations and 4.9 Q of process heat produced in an onsite boiler. Associated losses were 6.2 Q at the power plant and in the transmission lines, and 2.5 Q for the boiler, for a total energy requirement of 16.3 Q and a system efficiency (usable energy/total energy) of 47%. As seen in the right-hand panel, if the same amount of electricity and heat had been produced as CHP, the total fuel requirements would have been only 8.9 Q, giving a system efficiency of 85%. Much larger penetration of CHP into the industrial sector is possible by 2010 because more than three quarters of the thermal
capacity installed in industries today is likely to be retired by that date.16 The main barriers to greater adoption of CHP are non-technical, such as the numerous and sometimes conflicting state and local electricity and environmental regulations. © 2001 American Institute of Physics
Yahoo! FareChase - Search multiple travel sites in one click.
