The char formed during hydrothermal carbonisation can be deployed in a variety of ways. Feed material composition and reaction conditions have the greatest influence on the properties of the coal, depending on the field of application they can be varied for optimisation.
Mainly hydrochars from residues are used for energy generation (through combustion or gasification). The energetic potential of these chars varies based on the calorific value between 16-30 MJ / kg depending on the feed material. Besides the improved energy recovery, other process-related advantages come into play especially in the matter of sewage sludge disposal. This includes better drainability of the residual material due to its hydrophobic properties as well as hygienisation. Governmental regulations (waste law) has so far made it difficult to utilize hydrochar as a conventional fuel since feed materials defined as waste remain waste even in the carbonized state and may therefore only be used in incineration plants that inherent adequate permissions.
Other than combustion hydrochar can be gasified in a subsequent process step. During the gasification syngas consisting of large parts of CO and H2 as well as parts of CH4 and H2S is produced. An energy density increase of the gas can be achieved by methanation of the carbon monoxide. Also shifting the reaction conditions allows hydrogen production.
Another significant potential of hydrochar is seen in the area of high-performance carbons. Coal obtained from sewage sludge has been successfully applied as activated carbon powder. The adsorption properties were similar to commercially available products. Especially wastewater treatment plants can profit from these results since there is a great need for waste gas cleaning. Among others, further research concentrates on using biomass coal as carbon black substitute as well as electrode material in so-called "supercapacitors".
The main focus of the project objective is to advance the commercial usability of innovative biofuels in combustion plants according to air pollution regulations (1., 13. and 4. BImSchV / TA Luft) in Germany and to elaborate solution concepts for the dismantling of legal barriers while taking into account the approval capability. It is aimed to facilitate the permission process for plant operators, fuel manufacturers and authorities.Hydrochar from waste material of the paper industry is burned in a 120 KW plant with a permit according to 4. BImSchV/ TA Luft. The analysis of the emissions and ashes will give insight into its approval capability.