Oil-shale gasification by concentrated sunlight: An open-loop solar chemical heat pipe

Gasification of oil shales followed by catalytic reforming can yield synthesis gas, which is easily transportable and may also be used for producing liquid fuels. We report here on experiments performed at the Weizmann Institute's Solar Central Receiver involving the use of concentrated solar energy as the heat source for the gasification. A number of dual-axis tracking heliostat mirrors provided primary concentration, and compound parabolic concentrators (CPCs) were used for secondary concentration. In addition to being the first experimental study on this particular type of chemical storage of concentrated sunlight, new aspects of this work include demonstrations of the following: 1. (i)significantly higher synthesis gas yields than previously reported; 2. (ii) marked improvements in conversion efficiency in transparent reactors, as opposed to opaque reactors, both as fluidized beds, primarily due to better heat transfer; 3. (iii) a substantial increase in deliverable energy compared to the conventional retorting of oil shales, and considerable reduction in the resulting spent shale.