Hydrothermal carbonisation of organic waste for thermal energy generation

Different perspectives have been identified for HTC pretreatment technology in the energy sector including combustion, gasification and methanation. However, HTC can lead to a wide range of product quality considering the wide diversity in wet biowaste that can be used. In addition, as HTC is still an emerging technology on the market, there are limited references regarding the relevancy of using HTC as a thermal pretreatment from both the technical and economical point of view. To evaluate if HTC is a valuable pretreatment technology for the sake of thermal energy generation, a series of 15 different feedstock types have been tested in the HTC lab pilot of Laborelec, among which organic residues from the paper industry, food waste, green waste in summer and autumn, compost. The HTC lab pilot has a batch capacity of 100 kg wet feedstock. For each feedstock, a complete analysis of the mass and energy balances is provided together with the assessment of the final product quality. Based on the different tests realised , the methodology for mass and energy balance evaluation was also elaborated and improved to help future project managers in their project design and feasibility study. The 15 feedstock types were of very different nature and gave hydrochar of very different characteristics. However, it is possible to observe some general trends for the HTC products obtained from every feedstock type as alkalis were well reduced during the process and chlorine seems always decreased during HTC process.