A Review of Intermediate Pyrolysis as a Technology of Biomass Conversion for Coproduction of Biooil and Adsorption Biochar

The agenda to utilize and efficiently convert biomass has been raised to alleviate environmental problems and pressure on the reliance on fossil fuel. Intermediate pyrolysis has the ability to treat different biomasses and coproduction of biooil and adsorption biochar. This review article aims to evaluate the appropriateness of intermediate pyrolysis for the coproduction of biooil and adsorption biochar. It was observed that coproduced biooil is of high quality, stable, and miscible that can be used directly to existing engines or be easily blended. The biochar coproduced is good for adsorption but is not stable for microbial attack and hence unsuitable in soil treatment but for hydrometallurgy. Since the process is capable of treating waste biomass, it is an opportunity for further investigations in areas where wastes are plenty and less utilized. To increase the effectiveness of this technology for coproduction, optimizing parameters, design of efficient reactors, and use of catalyst must be worked upon.

Improving carbon product yields in biocarbon production by combining pyrolysis and anaerobic digestion

Solid carbon is an important raw material in industrial processes. Most of the charcoal produced today is via conventional carbonization, which suffers from huge carbon losses due to system inefficiency. Intermediate pyrolysis is principally similar to conventional carbonization and produces biocarbon while capturing the off gasses; among these off gasses is aqueous condensate, which is difficult to utilize due to the high water content and low energy content. This fraction can contain up to 25% of the carbon from feedstock, so utilization of this fraction is important for good overall carbon balance. Anaerobic digestion can be a promising tool for utilizing the carbon in the aqueous condensate by converting it into biomethane. Here, birch and spruce wood were pyrolyzed and the biomethane potential for the aqueous condensates was tested. The mass and carbon balances of the pyrolysis products of birch and spruce at two pyrolysis temperatures were performed, and biocarbon carbon yields ranging from 42% to 54% were obtained. Anaerobic digestion of the aqueous phases collected from the pyrolysis process was performed, with carbon recovery yields between 44% and 59%. A total carbon recovery of 77.8% to 85.7% was obtained, and the primary carbon losses were identified.

Prospective contributions of biomass pyrolysis to China’s 2050 carbon reduction and renewable energy goals

Recognizing that bioenergy with carbon capture and storage (BECCS) may still take years to mature, this study focuses on another photosynthesis-based, negative-carbon technology that is readier to implement in China: biomass intermediate pyrolysis poly-generation (BIPP). Here we find that a BIPP system can be profitable without subsidies, while its national deployment could contribute to a 61% reduction of carbon emissions per unit of gross domestic product in 2030 compared to 2005 and result additionally in a reduction in air pollutant emissions. With 73% of national crop residues used between 2020 and 2030, the cumulative greenhouse gas (GHG) reduction could reach up to 8620 Mt CO2-eq by 2050, contributing 13–31% of the global GHG emission reduction goal for BECCS, and nearly 4555 Mt more than that projected for BECCS alone in China. Thus, China’s BIPP deployment could have an important influence on achieving both national and global GHG emissions reduction targets.

Experimental studies of intermediate pyrolysis of woody and agricultural biomass in a fixed bed reactor

Biomass pyrolysis is an advanced process which leads to obtaining products as chars, primary tars and gases. Depending on pyrolysis conditions and reactor construction, the pyrolysis could be divided into three categories: slow, intermediate and fast. This work concerns the experimental analysis of an intermediate pyrolysis of biomass residues in a fixed bed reactor. As raw materials, pine bark and wheat straw were selected. Experiments were carried out at three temperatures: 400, 500 and 600 °C under constant volume flow rate of inert gas equal to 100 ml/min. Biomass samples were kept for 150 seconds in the hot zone. The main goal was to compare yields, elemental composition, and calorific values of received products under studied process conditions. The ultimate analysis of chars and organic fractions of oils was performed. Obtained results from ultimate analysis allowed to determine higher heating values by a theoretical correlation. The products of pyrolysis obtained at 600 °C characterized by the most energetic parameters. The higher heating value for organic fraction of tars was 31.62 MJ/kg while for char was 29.47 MJ/kg.

Effects of Algal Biomass Blending on Coal Decomposition Behaviour and Kinetics at Intermediate Pyrolysis Regimes

Co-pyrolysis of coal with biomass is becoming a popular method of reducing the net carbon dioxide emissions associated with the process. In present work, the pyrolysis of coal and algae was studied using thermogravimetric methods and the kinetics were analyzed using the Coats-Redfern integral method. The kinetics were evaluated for 1st and 2nd order reaction models. The effect brought by blending coal with algae on kinetics was studied via the analysis of pyrolysis of different coal-algae blends. The results revealed that the pyrolysis of coal and algae follows 2nd and 1st order kinetics with activation energy evaluated in the range 213.4-241.8 and 108.9-122.8 kJ/mol, respectively. It was observed that for coal-algae blending of 20-40% algae, intermediate pyrolysis, typical heating rates of 50-200 ºC/min was characterized by two distinct stages (ignoring the drying stage) that correspond to the individual decomposition of algae and coal. However, there was an evidence of coal-algae interactions during co-pyrolysis, which made the kinetics of the two distinct stages not to correspond to the kinetics of the individual materials.