Waste Recovery through Thermochemical Conversion Technologies: A Case Study with Several Portuguese Agroforestry By-Products

Abstract

Agroforestry waste stores a considerable amount of energy that can be used. Portugal has great potential to produce bioenergy. The waste generated during agricultural production and forestry operation processes can be used for energy generation, and it can be used either in the form in which it is collected, or it can be processed using thermochemical conversion technologies, such as torrefaction. This work aimed to characterize the properties of a set of residues from agroforestry activities, namely rice husk, almond husk, kiwi pruning, vine pruning, olive pomace, and pine woodchips. To characterize the different materials, both as-collected and after being subjected to a torrefaction process at 300 °C, thermogravimetric analyses were carried out to determine the moisture content, ash content, fixed carbon content, and the content of volatile substances; elementary analyses were performed to determine the levels of carbon, nitrogen, hydrogen, and oxygen, and the high and low heating values were determined. With these assumptions, it was observed that each form of residual biomass had different characteristics, which are important to know when adapting to conversion technology, and they also had different degrees of efficiency, that is, the amount of energy generated and potentially used when analyzing all factors.

Production of Biochar from Vine Pruning: Waste Recovery in the Wine Industry

“…The mass loss presented an average value of 78.31 ± 1.00%. The values verified in the mass loss are in agreement with the values presented in previous works, such as those by Tag et al (2016) or [23,33]. The values presented in the referred works are included in the range 75-80% for process temperatures of 400 • C and equivalent residence time.…”

“…However, given the considerable volumes of biomass produced annually throughout the country, it is very difficult to collect and use it, given the dispersion of wine production throughout the territory, which is usually abandoned, or else eliminated by burning the leftovers [29,30]. Despite the recognized properties as a fuel, previously reported in several works, such as those by Duca (2020), where several characterizations of materials and different forms of energy recovery, such as anaerobic digestion, pyrolysis or gasification, are presented, still exists a deep lack of knowledge concerning creating value chains using these materials and about the best options to manage the amounts yearly generated [31][32][33][34].…”

Pachira aquatica fruits shells valorization: renewables phenolics through analytical pyrolysis study (Py-GC/MS)

“…The PAS presented between 75.35 and 77.95% of volatile matter, values close to those observed for others lignocellulosic biomass (BARBOSA et al, 2019;NUNES et al, 2020). The high volatiles content is an important characteristic for biomass application in pyrolysis processes, because it indicated that a large fraction of biomass is converted into steam and gas when heated, which leads to the possibility of high yield of bio-oil .…”

“…The characterization results of dry basis biomass (Table 1) indicated suitable values for thermochemical conversion processes: low moisture and ash content, high volatiles content, and a moderate bulk density. The moisture reduces the HHV and inhibit ignition because an amount of energy is used to dry the biomass (SAMADI et al, 2020;NUNES et al, 2020). In addition, high moisture content can damage the storage, causing fungal proliferation and material degradation, as well as increasing transport costs.…”

Thermochemical Conversion Processes as a Path for Sustainability of the Tire Industry: Carbon Black Recovery Potential in a Circular Economy Approach

“…The laboratory procedure used in the present study was similar to the one used for the carbonization of various types of biomass, and previously described by Nunes et al [45]. The tires collected were divided into five groups composed by 5 samples each, with approximately 750 g of material.…”