By Josh Perry, Editor
Researchers from Tomsk Polytechnic University have demonstrated that pyrolysis, a process of biomass decomposition in an oxygen-free environment, can occur automatically when biomass is heated to certain temperatures and this could make biofuel generation more efficient and viable.
Arkadievsky peat, the Tomsk Oblast, Russia. (Tomsk Polytechnic University)
According to a report from the university, the scientists reported on a variety of materials, including pine sawdust, chips from different types of wood, two types of peat, and straw.
“In autothermal processes,” the article explained, “the reaction temperature is maintained due to own thermal release. Practically, it allows the reduction of the cost of the technological process, increasing the efficiency of processing and the reduction of the number of auxiliary equipment.”
To test the thermal effect of the pyrolysis, researchers conducted thermogravimetric (TGA) and differential thermal analysis on the biomass samples. They found that the amount of heat released by the process was more than what was required for heating the material.
“This effect for straw and wood is associated with the processes of decomposition of cellulose, lignin, and hemicellulose during pyrolysis,” the article continued. “These processes generate additional heat. In the case of Sukhovskoy peat, this effect is due to the decomposition of cellulose, humic and fulvic acids.”
The research was recently published in the Journal of Thermal Analysis and Calorimetry. The abstract stated:
“The harmful emissions from traditional organic fuels combustion cause irreparable harm to the environment, which leads to the conclusion that it is necessary to reorient the energy sector to renewable energy sources such as biomass. Traditional methods of combustion are of little use for the energy use of biomass. This fact forces us to search new efficient technologies for its processing.
“Pyrolysis is one of the most universal and promising areas of biomass processing. However, its implementation requires significant heat costs, which has a considerable impact on the result of the feasibility study.
“The aim of the work is to study the thermal effects observed in low-temperature pyrolysis and to assess the possibility of autothermal biomass processing. Straw, chips from various types of wood, pine sawdust and peat from two deposits of the Tomsk region (Russia) were considered as a biomass. A physical experiment, differential thermal analysis, gas chromatography and heat balance equations were used in the work.
“It has been established that low-temperature pyrolysis of biomass is accompanied by a positive value of the thermal effect in the temperature range of 220–580 °C and varies from 393 to 1475 kJ kg−1 depending on the type of raw materials being processed.
“The value of this effect makes it possible to organize pyrolysis of biomass in an autothermal regime with preliminary drying: maximum moisture content for straw of 19.9%, wood chips of 10.4%, sawdust of 9.7% and Sukhovskoy peat of 9.5%.”