Geological eras and specific environmental conditions are necessary to transform biomass into coal: at the University of Trento a process is being developed which produces biochar from waste biomass in a few hours.
This process is referred to in the literature as Hydro-Thermal Carbonization (HTC). HTC is a hydro-thermal process: it occurs in a liquid water environment and at a relatively high temperature. The required temperature is in the range 180–250 °C, with a pressure of 10-50 atmospheres. Operating in a watery environment makes HTC ideal for treating biomass with a high moisture content: the organic fraction of municipal solid waste, agroindustrial waste (grape marc, fruit pulp, waste from the vegetable oil industry, animal waste), gardening waste (twigs, leaves) and sewage sludge. The HTC process can treat waste that would otherwise be sent for anaerobic digestion, composting, or to landfill. The operating conditions – moderate temperature and pressure – mean that the process can be implemented also at a small or medium scale, and the level of technology is suitable even for small and medium-size enterprises.
In the operating conditions described above, with the possible addition of a suitable catalyst, the biomass transforms into biochar. Biochar is enriched in carbon content, while the percentage of oxygen decreases. Depending on the temperature and duration of the process, the biomass turns into a substrate with peat-like, lignite-like, and possible coal-like characteristics.
What can this product be used for? The possibilities are endless: from energy production (together with or instead of fossil carbon fuels) to higher added-value uses including as soil amendments (instead of fossil peat), as an adsorbent in filtration or water treatment, or as a constituent in carbon electrodes for batteries or fuel cells.
At the Department of Civil, Environmental and Mechanical Engineering (DICAM) of the University of Trento, I coordinate a group of young researchers, and since 2013 we have been working on the HTC process and the various possible uses for the biochar produced. The research group addresses strictly scientific aspects (publications, participation to congresses) and, in addition, is in close relationships with local companies: two of these, Contarina SpA (Treviso) and Atzwanger SpA (Bolzano), have signed contracts with DICAM to provide financial support to the research group for its activities in the field of HTC.
With the doctoral student Daniele Basso, we participated in the business ideas competition D2T Start Cup with the project HTC BIO Innovation which was selected as the best in the Green category.