Thermoeconomic analysis of oil shale retorting processes with gas or solid heat carrier

Oil shale is regarded as one of the most promising alternative energy resources. In China, oil shale retorting technologies mainly consist of (ⅰ) conventional Fushun retorting technology, (ⅱ) gas full circulation retorting technology, and (ⅲ) Dagong retorting technology. There have been till now few quantitative analyses of the three technologies. This paper focuses on thermoeconomic analysis of three processes of these technologies. Results show that the exergy destruction of the Dagong retorting process is 38.6%, much lower than that of the Fushun retorting process, 65.7%. The total capital investment of the gas full circulation retorting process is the highest, 1.7 billion CNY, followed by the Dagong retorting process, 1.4 billion CNY and the Fushun retorting process, 1.2 billion CNY. The ROI (Return on investment) of the Dagong retorting process is the highest, 18%, while that of the Fushun retorting process is the lowest, 8.6%.