由於京都議定書的實行生效，我國政府在面對低污染的世界潮流，天然氣的擴大使用成為能源政策中重要的一部份。然而目前各天然氣公司在營業區域的劃分下，其天然氣的普及程度卻明顯偏低。本研究以2000年至2004年的天然氣公司做為實證資料，以超對數成本函數（translog cost function）來估計天然氣公司的最小有效規模產出，進而推估出每家公司在其營業區內之最適普及率。接著再利用縱橫資料（panel data）模型，以討論天然氣最適普及率的影響因素。實證結果顯示，樣本天然氣公司平均最適產出為162,400,527立方公尺，遠高於目前平均產出47,736,578立方公尺。北部地區在最小有效規模產出標準下，大部分公司需以完全普及做為目標，並隱含北部天然氣公司有進一步合併的空間。南部地區的最適普及率約為50％，且其公司規模明顯小於北部地區。而影響天然氣最適普及率的因素，以安裝價格以及營業區域的差異為主要原因。 After the international treaty of “Kyoto Protocol”, the substitution of low-pollution for high–pollution energy has become a worldwide concern. Thus the expansion of natural gas use is one of the important goals in Taiwan’s energy policy. However, under current regional division for each locally monopolistic natural gas company, the coverage rates are still low. Based on a panel data set which includes 20 gas utility companies over the period from 2000 to 2004, this thesis first uses the concept of Minimum Efficient Scale (MES) and a translog cost function to estimate the optimal coverage rate of each natural gas companies in current business division, and then use the panel data model to discuss the determinants of optimal coverage rate. The result shows that the average optimal gas providing level is 162,400,527 cubic meters which is higher than the realized gas providing level. The results also show that that natural gas companies in the northern part of Taiwan should take complete coverage as the goal and imply that they should be further merged. On the other hand, the optimal coverage rate of natural gas usage in the southern Taiwan is 50 percent. As to the determinants of coverage rate, the configuration price and regional difference are the two primary factors to affect the natural gas usage.
