In the 2000 fiscal year, we started a three year research project, which is the first study applying "area-wide pinch technology analysis", supported by the New Energy and Industrial Technology Development Organization (NEDO), an affiliated organization of Japan's Ministry of Economy, Trade and Industry. We have found a large amount of energy saving potential by the energy sharing between multiple sites in one major industrial area, which is a heavy chemical industry field. The found potential is 641,000 kL/year, annual crude oil conversion in the Chiba industrial area, which is one of the biggest heavy chemical complexes in Japan, which is almost the amount of crude-oil consumption in one day for all of Japan. We could establish a method of application of area-wide pinch technology analysis and a procedure to develop an energy sharing project between two sites in the industrial area. It is convincing that area-wide pinch technology could be helpful and useful to provide optimal information for energy saving in an industrial area.