Catarina Nobre
VALORIZA, Portugal
Title: Potential of “Montado†wastes as feedstock for thermal gasification
Biography
Biography: Catarina Nobre
Abstract
The “Montado” ecosystem is composed mainly by Quercus species. It’s wastes, e.g. acorn wastes are mostly used for animal feed or left behind in the fields. In Portugal, 55% of these wastes (especially in the North and Alentejo regions) do not have any type of valorization. Due to their physical-chemical composition and relative abundance (average annual production of 400,000 t/y) acorn wastes, are a very interesting feedstock to use in energy recovery technologies, particularly thermal conversion processes aiming at producing renewable gases (e.g., syngas, hydrogen or biomethane).
The present study aimed to investigate the gasification potential of “Montado” wastes, such as lignocellulosic materials and acorn wastes. Firstly, all of the feedstock was cleaned in a mechanical process using sieves and dried in a rotary dryer. These processes made it possible to separate the crumb from the by-products (acorn husks, lignocellulosic components, and leaves) through their density. The drying process reduced 25 wt.% moisture content from the feedstock. Feedstocks were then characterized (ultimate and thermogravimetric analysis) and subjected to gasification tests (600, 650 and 700 °C) to understand the influence of temperature on syngas quality, namely in H2 production potential. The results showed that increasing temperature increases the syngas heating value from 5.2 to 5.6 MJ/m3. The H2 concentration also increased from 15.5 to 17.6 vol.%. The highest cold gas efficiency (CGE) was obtained at the highest testing temperature with a value of around 70 %. Overall, these tests indicate that “Montado” wastes can be used as feedstock in gasification, yielding good quality syngas, with potential to further clean and purify for H2 production. Further testing varying other operational parameters (e.g, feeding rate, ER) is still needed to validate this approach, as well as a techno-economic assessment to study the feasibility of these wastes in syngas and renewable gases production.