Upgrading fuel potentials of waste biomass via hydrothermal carbonization

Abstract

In recent decades, massive exploitation of fossil fuels caused a growing demand for the production of energies from renewable sources. Hydrochar obtained from waste biomass via hydrothermal carbonization (HTC) possesses good potentials as a biofuel. Therefore, we performed HTC of corn cob, paulownia leaves, and olive pomace at different temperatures (180, 220, and 260 oC). The main goal of this study was to comparatively evaluate the influence of HTC conditions on the structure and fuel characteristics of the obtained solids. The results showed that the yields of hydrochar decrease significantly with increasing temperature in all samples. The carbon content and higher heating value increased and reached the highest values in hydrochars obtained at 260 oC, while the content of volatile matter decreased. Furthermore, the Van Krevelen diagram reveals that the transformation of feedstock to lignite-like products upon HTC was achieved. In this study, the results showed that processes of dehydration and decarboxylation during HTC provoke intensive biomass transformation and that hydrochars obtained at higher temperatures have significantly enhanced fuel properties and fewer volatiles compared to the feedstock.

Hydrothermal Carbonization of Waste Biomass: A Review of Hydrochar Preparation and Environmental Application

“…In general, studies show that the feedstock type and HTC temperature have the most significant effects on hydrochar properties [1][2][3]7]. Thus, optimization of the process is crucial in achieving characteristic products for specific applications based on the precursor biomass and the end use of the material.…”

“…In addition, the use of waste biomass as a sustainable resource has gained recognition due to its potential to decrease greenhouse gas emissions [6]. However, low energetic potential and stability, high ash content, hygroscopic nature, storage issues, and volatiles released during combustion impair the motivation for its utilization [7]. Significant strides have been made in the adoption of thermochemical conversion processes that can convert biomass into multifunctional products [1,7].…”

“…However, low energetic potential and stability, high ash content, hygroscopic nature, storage issues, and volatiles released during combustion impair the motivation for its utilization [7]. Significant strides have been made in the adoption of thermochemical conversion processes that can convert biomass into multifunctional products [1,7]. These highly effective processes utilize heat to transform biomass into desirable biofuels, adsorbents, or valuable chemicals (bio-oil, aldehydes, phenols, ketones, acids, and furan derivates) [1,2,8].…”

“…It is a cost-Processes 2024, 12, 207 2 of 17 effective and environmentally friendly process that operates at moderate temperatures (180-280 • C) and uses water as a reaction medium (Figure 1). The HTC process offers significant advantages, including the carbonization of wet biomass without the need for drying and the absence of gas emissions due to the dissolution of oxides in process water [2,7]. During the HTC process, the raw material undergoes several reactions that include hydrolysis, dehydration, decarboxylation, aromatization, and condensation [11,12].…”

Energy plants as biofuel source and as accumulators of heavy metals

“…The threat that heavy metals present causes decreased quantity and quality of crop yields and agricultural products, and loss of fertile soil, freshwater, and ecosystems [1]. Furthermore, problems related to energy and environmental protection are one of the burning issues in the 21 st century [2]. Biogas/biomethane represent the future of green energy.…”