@misc{GonzalezAriasGomezGonzalezCastanoetal., author = {Gonz{\´a}lez-Arias, Judith and Gomez, X. and Gonzalez-Castano, Miriam and Sanchez, Marta Elena and Rosas, J. G. and Cara-Jim{\´e}nez, Jorge}, title = {Insights into the product quality and energy requirements for solid biofuel production: A comparison of hydrothermal carbonization, pyrolysis and torrefaction of olive tree pruning}, series = {Energy}, volume = {Vol. 238, part C (2022)}, journal = {Energy}, issn = {0360-5442}, doi = {10.1016/j.energy.2021.122022}, pages = {12}, abstract = {For a bio-economy establishment, understanding the energy consumption needs to produce solid biofuels is a key point. Herein, olive tree pruning was treated by both dry (pyrolysis and torrefaction) and wet (hydrothermal carbonization) thermal treatments. Product yield, solid quality and energy consumption were assessed. The solids were characterized by means of chemical and thermogravimetric analysis. For all treatments, coal-like solid products were obtained, with higher heating values (HHV) of almost 30 MJ kg-1 in most of the conditions evaluated. Chars from pyrolysis presented the greater carbon content (between 76 and 85 wt\%) but also the higher ash content (ranging from 6 to 9 wt\%). From an energy consumption perspective, torrefaction registered the lowest energy consumption (between 5.85 and 20.76 MJ kg-1 char). The highest energy contents per kilogram of char produced were also reflected in torrefaction samples, with values around 11 MJ kg-1 char. Although the obtained HHVs were greater for pyrolysis chars the higher mass yields obtained in torrefaction makes it more profitable. The least severe conditions allowed to obtain a positive energy balance only with the solid phase considered. Nonetheless, further room for improvement is possible since the gas and liquid phases may also be valorised.}, language = {en} } @misc{GonzalezAriasBaenaMorenoGonzalezCastanoetal., author = {Gonz{\´a}lez-Arias, Judith and Baena-Moreno, Francisco Manuel and Gonz{\´a}lez-Casta{\~n}o, Miriam and Arellano-Garc{\´i}a, Harvey}, title = {Economic approach for CO2 valorization from hydrothermal carbonization gaseous streams via reverse water-gas shift reaction}, series = {Fuel}, volume = {313}, journal = {Fuel}, issn = {0016-2361}, doi = {10.1016/j.fuel.2021.123055}, pages = {1 -- 7}, abstract = {In this work the economic performance of valorizing the gaseous stream coming from hydrothermal carbonization (HTC) of olive tree pruning is presented as a novel strategy to improve the competitiveness of HTC. The valorization of the commonly disregarded gaseous stream produced in this thermochemical treatment was proposed via the Reverse Water-Gas Shift reaction. This allows to obtain syngas for selling and therefore improving the overall economic performance of the process. To this end, three plant sizes were selected (312.5, 625 and 1250 kg/h of biomass processing). The parameters with a higher share in the total cost distribution along with the revenues from the hydrochar and the syngas selling were further evaluated. The results evidenced that with the assumptions taken, the overall process is still not profitable. To reach profitability, syngas selling prices between 2.2 and 3.4 €/m3 are needed, revealing that this proposal is not economically attractive. Alternatively, a lack of competitiveness in the current market is revealed with hydrochar selling prices between 0.41 and 0.64 €/kg to make the project profitable. The catalyst cost, sharing approximately 20\% of the total cost, is the parameter with the highest impact in the total economics of the process. The second one is the hydrogen price production, representing almost 16\% of the total. Investment subsidies are also examined as a potential tool to cover part of the initial investment. These results evidenced that further efforts and measures are needed to push forward in the path towards circular economy societies.}, language = {en} }