In 2016, the DOE estimated the United States has 205 million tons of available biomass waste that include algae, forestry, agricultural, and municipal waste. These waste streams are often uncollected or underutilized. One common thermochemical processing method capable of converting a wide variety of organic residues into a value-added product is hydrothermal carbonization (HTC). HTC converts wet substrates at operating temperatures ranging between 150 – 280 °C and autogenous pressures to form a hydrochar product with applications in soil amendment, metal absorbent, and solid fuel. HTC has been broadly applied in thousands of published studies that evaluate the effectiveness of HTC using a subset of feedstocks and/or operating conditions. Similarly, the hydrochar products have been selectively characterized based on desired properties of the application. To date, connections between HTC studies have been limited to direct comparisons on results that have similar operating conditions and/or feedstocks. Therefore, we perform a meta-analysis on current HTC work in conjunction with experimental runs to assess the dependency of feedstock and process conditions on HTC performance.<br/>Our meta-analysis model evaluates over 100 datasets from HTC runs using miscanthus, cellulose, rice husk, and wheat straw. The HTC performance and corresponding hydrochar properties are considered with a confidence level on their dependency to the HTC operating temperature, reactor volume, reaction time, and reactor stirring. Hydrochar properties considered in the meta-analysis include elemental content, higher heating value, and proximate composition. Meta-analysis trends are experimentally assessed using miscanthus, food waste and brewer’s spent grain under HTC conditions between 190 – 250 °C and two differently sized reactors. Experimental HTC runs revealed synergistic effects when combining waste feedstocks. In addition, HTC runs using food waste produced different in hydrochar yields when performed in reactors of different size. This study reveals important considerations in comparing and evaluating HTC performance with other studies.

Meta-analysis on hydrothermal carbonization: Influence of process conditions on product yields and composition

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.