New Process Design for the Gasification of Waste Using Fresnel Solar Collectors

Sustainable Waste Management is crucial for reducing environmental impact of human activity. Various technologies have been devised to transform biomass and other waste into environmentally friendly energy sources, encompassing fuel, heat, electricity and organic fertilizer. The supercritical water gasification (SCWG) process could be a viable alternative to conventional treatments, since a high-quality gas is obtained as product. To minimize the cost-effectiveness of SCWG, in this work we propose the use of solar thermal energy supplied by Fresnell solar collectors specifically designed for high-pressure fluids and stored in an innovative heat-storing system. The design consists of a serpentine formed by a high-pressure piping. In order to transfer energy from the internal wall of the steel tube, hit by solar radiation, it is necessary to insert, between the spaces surrounding the individual high-pressure tubes, a highly conductive material, identified in a compact matrix of molten aluminum. This new process has been called SUNGAS and aims to significantly reduce operational costs by the exploitation of two different renewable sources, such as solar thermal energy and solid waste, thus promoting the application of this technology on an industrial scale. In the present paper, the design of the innovative continuous solar reactor at industrial scale is presented, together with thermal and empirical modeling based on the biomass conversion. Results show that SUNGAS could represent a feasible method for syngas production from OM and similar biomass waste.