自古以來，能源一直都扮演著相當重要的角色，尤其是工業革命之後，能源的應用更是大幅的增加，以至於燃料的使用量也隨之大幅上升。能量的來源，從早期的燃燒木頭、煤炭，到現今的利用石油、天然氣、生質能、太陽能等，種類越來越多，但由於化石能源的燃料使用率低、污染性高，並且專家預估地球上化石燃料可能在未來幾十年內耗盡，而太陽能及生質能成本太高且效率不高或因發展困難等種種因素，於是“什麼是最合適的替代能源”成了能源界最熱們的課題。
本文提出固態氧化物燃料電池SOFC(Solid Oxide Fuel Cell)/小型氣渦輪機(Small Gas Turbine)發電系統之效能分析(performance analysis)，利用氣對氣熱交換器(gas to gas heat exchanger)將SOFC所排出之廢熱回收利用，用以加熱由空氣壓縮機出口之高壓空氣，使之達到氣渦輪機入口溫度，推動氣渦輪機葉片作功。本文利用系統中各個元件的能量分析，求出整個系統的熱效率(thermal efficiency)，並將結果加以討論，以為系統最佳化之依據，進一步尋求能源最佳運用之系統設計，並期能達到高效率與節約能源的目的以及得到變數與系統效率間的關係。

It is known that energy play the very important role of Today’s Life, especially the days after revolution of industry II, the amount of energy utilizing becomes very large. We can get energy by burning fossil fuel. But the utilizing efficiency of fossil fuel is very low and it makes up very heavy pollutions. Experts say that the resource of fossil fuel will be used up in several decades. Today, Biomass and Solar energy cost very high and the efficiency of them is not very high, or the technique of them is not very mature or easy. So they can’t be utilized generally. Today, finding ‘What is the best way to product energy’ becomes the most important task to overcome.
This propose brings up the efficiency analysis of a hybrid system combined Solid Oxide Fuel Cell (SOFC) and Small Gas Turbine (GT), and using gas to gas heat exchanger to recycle the heat of the mixed gas, outlet from SOFC, to heat the pressured air, outlet from the air compressor. Then the heat can make the air to the needed temperature entering the gas turbine (turbine inlet temperature, TIT) to move the blade making power. The propose uses the energy analyses of every component of system to find the system overall thermal efficiency, then we find the results. Finally we use the conclusion to be the basis of system optimum and to find another better optimal system design. Then we wish to find the aim of high efficiency and saving energy and the relation of control parameters and system efficiency.

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