Science advances in the production of biomass for energy

Research developed by the Universidade Estadual Paulista (Unesp/Dracena) with the participation of Embrapa Meio Ambiente (SP) managed to incorporate glycerin into the pellets to enhance their use in the Brazilian agroindustry. Pellets are solid fuels based on plant biomass residues, such as sawdust, wood chips and sugarcane bagasse, among others, used to generate electrical and thermal energy in plants, companies and residential heating. Agropellet models, containing glycerol, are denser and can offer more sustainable solutions to recover energy from bioethanol and biodiesel byproducts, reducing dependence on processing wood and woody biomass for traditional solid biofuels.

Researcher Andre May, from Embrapa Meio Ambiente, explains that pellets are like “cubes” of biomass, produced from plant waste, especially wood, from large production chains. Currently, the main application of wood pellets in Brazil is in the generation of thermal energy for industries and commerce, being used by pizzerias, bakeries, hotels, water parks, swimming gyms, painting greenhouses, food industries, laundries, etc.

The use of these byproducts already adds sustainability to energy production. With the study, which was financed by the São Paulo Research Foundation (Fapesp), the scientists managed to increase the biomass density of the pellets, by incorporating glycerol into the sugarcane bagasse mixture ( first generation ethanol - 1G) and lignocellulosic residue (coming from the production of second generation ethanol - 2G).

Glycerol is a byproduct of biodiesel. It offers a suitable additive for the manufacture of solid fuels. However, studies on biomass structures with glycerol for energy generation still needed more experiments and tests to develop alternatives related to non-wood pellets, in addition to increasing understanding of the relationships between raw materials, products and processes.

“Research has shown that it is possible to condense higher density energy into pellets than the original biomass. This expands the possibility of uses and markets for these products, such as in transporting and storing energy in a safer way”, says May.

Research showed formation of quality non-wood pellets

Ronaldo Viana, researcher and professor at Unesp, leader of the study, adds that the objective of the project was to evaluate whether the addition of glycerol to agro-industrial bioethanol residues, sugarcane bagasse (first generation) and lignocellulosic residue (second generation) , could develop agropellets suitable for heating and energy production.

The patterns of the generated products were analyzed for volatile matter, fixed carbon, density, appearance and calorific value. Furthermore, thermogravimetry (thermal analysis technique) and scanning electron microscopy of the formed pellets were performed to provide more information about their thermal stability, morphology and propensity to form slag (impurities) and scale.

“We obtained evidence of the formation of quality pellets using these raw materials. Its products can be as important as biofuels made from top quality wood, providing excellent industrial solutions, with high performance from the pelletizing line, capable of generating heat and energy in the most rigorous residential and commercial combustion systems”, notes Viana.

Glycerol and its importance in pelletization

Glycerol is the most significant by-product from biodiesel. Global production of this biofuel exceeds 46 million cubic meters, which is a significant amount, with a tendency to increase until 2050. Its conversion to biofuels and biochemicals offers the biodiesel industry solutions to balance economic advantages and socio-environmental challenges.

The use of glycerol has direct application as a fuel and also as an additive for fuel and food. Fuel glycerol is highly viscous and produces a significant amount of ash, reducing the calorific value. As a result, it limits the thermal conversion efficiency of furnaces, boilers, engines and microturbines.

The most common method of integrating glycerol into biomass is as an additive for burnable pellets. Pelleting offers a cost-effective way to convert low-quality inorganic and biogenic materials into feedstocks for energy-dense, granular solid fuels, improving their transportation, storage and utilization.