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Impact of different agricultural biomass residues on the performance of continuous solar-steam gasification
(2025-11-02)
Chuayboon, Srirat
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Abanades, Stéphane
Solar-driven biomass gasification represents a promising avenue for sustainable carbon-neutral fuel production. Nevertheless, the types of raw biomass materials play a vital role in continuous solar gasification performance. In this study, continuous solar-steam gasification with various agricultural crop residues was experimentally carried out in a 1.5 kW<inf>th</inf> solar gasifier to investigate the influence of biomass types on performance and efficiency under different operating temperatures up to 1400 °C. Seven agricultural residues were used as feedstocks, including oil palm wastes (palm mesocarp fiber, palm empty fruit bunch, and palm kernel shell), bagasse, betel nut, coconut fiber, and rice husks. Results demonstrated that the system can effectively perform with all biomass types with high-quantity and high-quality syngas production. The process revealed exceptional performance and efficiency, including the total maximum syngas yield range of 67.9–81.5 mmol/g<inf>dry biomass</inf>, reaching 81.4–95.2 % of the theoretical total syngas yields, maximum energy upgrade factor (1.05–1.35), reaching 94.2–97.3 % of the theoretical values, and maximum carbon conversion (87.2–96.9 %). The feedstock types showed a significant influence on gasification outcomes. Palm oil empty fruit bunch, betel nut, and palm mesocarp fiber were promising candidates for solar gasification with their high volatile content and significant decomposition potential, followed by coconut fiber and bagasse. Nevertheless, palm kernel shell and rice husk were found to be unsuitable biomasses for continuous solar-steam gasification because of the issues of reduced gasification activity and reaction rate limitations, due to a high density for palm kernel shell and a high ash content for rice husk. A temperature of 1300 °C was recommended to carry out continuous solar-steam gasification, leading to the maximum solar-to-fuel energy conversion efficiency in the range 13.7–18.9 %. This study provides insights into the influence of agricultural residue types on the solar-steam gasification process, while assisting in the proper biomass residue selection for efficient continuous solar gasification.
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Carbon capture through solar-driven CO2 gasification of oil palm empty fruit bunch to produce syngas and biochar
(2025-05-15)
Al-Muraisy, Saqr A.A.
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Chuayboon, Srirat
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Soares, Lais Americo
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Buijnsters, J. G.
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Ismail, Shahrul bin
Oil palm empty fruit bunch (OPEFB) is an abundant organic waste in Malaysia that is often disposed of through field burning. A previous study has shown that solar-driven steam gasification of OPEFB can produce hydrogen-rich syngas with an energy upgrade factor of 1.2 and a carbon conversion efficiency of 95.1 %. Beyond its potential as a biofuel, OPEFB can also act as a carbon sink, capturing photosynthetically stored carbon. This study explores the potential of amplifying OPEFB's negative carbon emissions through solar-driven gasification, using CO<inf>2</inf> as the gasifying agent. In this work, a Central Composite Design (CCD) approach was employed to assess the influence of temperature (1100–1300 °C) and CO<inf>2</inf>/OPEFB molar ratio (1.6–3.0) on H<inf>2</inf>/CO molar ratio and energy upgrade factor, with a constant OPEFB flow rate of 1.8 g/min. The results demonstrated that at an energy upgrade factor of 1.4, 94.9 % of the total carbon was converted into syngas with a H<inf>2</inf>/CO molar ratio of 0.3. The maximum observed net carbon capture yield of 0.4 g C/g OPEFB was achieved at 1300 °C and a CO<inf>2</inf>/OPEFB molar ratio of 3.0. The remaining carbon (94.4–95.7 wt %) was converted into biochar with low heavy metal content, which has potential as a soil enhancer.
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Solar-driven chemical looping methane reforming using zno oxygen carrier for syngas and zn production in a cavity-type solar reactor
(2020-11-01)
Chuayboon, Srirat
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Abanades, Stéphane
Converting sunlight into chemical fuels and metal commodities, via solar thermochemical conversion processes, is an attractive prospect for the long-term storage of renewable energy. In this study, the combined methane reforming and ZnO reduction in a single reaction for co-production of hydrogen-rich syngas and metallic Zn was demonstrated in a flexible solar thermochemical reactor prototype, driven by highly concentrated sunlight. Using solar energy as the process heat source in chemical-looping methane reforming with the ZnO/Zn oxygen carrier is a means to reduce the dependence on conventional energy resources and to reduce emissions of CO<inf>2</inf> and other pollutants, while upgrading the calorific value of the feedstock for the production of energy-intensive and high-value chemical fuels and materials. On-sun experiments were carried out with different operating parameters including operating temperatures (800–1000<sup>◦</sup>C), inlet methane flow-rates (0.1–0.4 NL/min), and inlet ZnO feeding-rates (0.5–1.0 g/min) both in batch and continuous modes under reduced (0.15 and 0.45 bar) and atmospheric pressures (0.90 bar), thereby demonstrating solar reactor flexibility and reliability. As a result, increasing the temperature promoted net ZnO conversion at the expense of favored methane cracking reaction, which can be lowered by decreasing pressure to vacuum conditions. Diminishing total pressure improved the net ZnO conversion but favored CO<inf>2</inf> yield due to insufficient gas residence time. Rising ZnO feeding rate under a constant over-stoichiometric CH<inf>4</inf>/ZnO molar ratio of 1.5 enhanced ZnO and methane consumption rates, which promoted Zn and syngas yields. However, an excessively high ZnO feeding rate may be detrimental, as ZnO could accumulate when the ZnO feeding rate is higher than the ZnO consumption rate. In comparison, continuous operation demonstrated greater performance regarding higher ZnO conversion (X<inf>ZnO</inf>) and lower methane cracking than batch operation. High-purity metallic Zn with a well-crystallized structure and of micrometric size was produced from both batch and continuous tests under vacuum and atmospheric pressures, demonstrating suitable reactor performance for the solar thermochemical methane-driven ZnO reduction process. The produced Zn metal can be further re-oxidized with H<inf>2</inf>O or CO<inf>2</inf> in an exothermic reaction to produce pure H<inf>2</inf> or CO by chemical-looping.
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Solar chemical looping reforming of methane combined with isothermal H2O/CO2 splitting using ceria oxygen carrier for syngas production
(2020-02-01)
Chuayboon, Srirat
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Abanades, Stéphane
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Rodat, Sylvain
The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle (CeO<inf>2</inf>/CeO<inf>2</inf><inf>−</inf><inf>δ</inf>) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and methane to syngas in the temperature range 900–1050 °C. Experiments were carried out with different ceria shapes via two-step redox cycling composed of endothermic partial reduction of ceria with methane and complete exothermic re-oxidation of reduced ceria with H<inf>2</inf>O/CO<inf>2</inf> at the same operating temperature, thereby demonstrating the capability to operate the cycle isothermally. A parametric study considering different ceria macrostructure variants (ceria packed powder, ceria packed powder mixed with inert Al<inf>2</inf>O<inf>3</inf> particles, and ceria reticulated porous foam) and operating parameters (methane flow-rate, reduction temperature, or sintering temperature) was conducted in order to unravel their impact on the bed-averaged oxygen non-stoichiometry (δ), syngas yield, methane conversion, and solar reactor performance. The ceria cycling stability was also experimentally investigated to demonstrate repeatable syngas production by alternating the flow between CH<inf>4</inf> and H<inf>2</inf>O (or CO<inf>2</inf>). A decrease in sintering temperature of the ceria foam was beneficial for increasing syngas selectivity, methane conversion, and reactor performance. Increasing both CH<inf>4</inf> concentration and reduction temperature enhanced δ with the maximum value up to 0.41 but concomitantly favored CH<inf>4</inf> cracking reaction. The ceria reticulated porous foam showed better performance in terms of effective heat transfer, due to volumetric absorption of concentrated solar radiation and uniform heating with lower solar power consumption, thereby promoting the solar-to-fuel energy conversion efficiency that reached up to 5.60%. The energy upgrade factor achieved during cycle was up to 1.19. Stable patterns in the δ and syngas yield for consecutive cycles with the ceria foam validated material performance stability.
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Syngas production via solar-driven chemical looping methane reforming from redox cycling of ceria porous foam in a volumetric solar reactor
(2019-01-15)
Chuayboon, Srirat
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Abanades, Stéphane
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Rodat, Sylvain
The solar-driven chemical looping methane reforming using the non-stoichiometric ceria redox cycle (CeO<inf>2</inf>/CeO<inf>2-δ</inf>) was experimentally investigated for both syngas production and isothermal H<inf>2</inf>O/CO<inf>2</inf> splitting using a directly irradiated volumetric solar reactor in the temperature range of 950–1050 °C. Experiments were performed via two-step redox cycling encompassing endothermic ceria reduction with methane (partial oxidation of methane) and exothermic oxidation of reduced ceria with H<inf>2</inf>O/CO<inf>2</inf> under the same operating temperature. Ceria was used as oxygen carrier material in the form of reticulated porous foam structure and different operating parameters (methane flow-rate and reduction temperature) were varied in order to emphasize their impact on the bed-averaged oxygen non-stoichiometry (δ), syngas yield, methane conversion as well as solar reactor performances. The ceria cycling stability was also examined. The increase of both the methane flow-rate and reduction temperature promoted the δ in turn leading to a substantial enhancement in the syngas yields that reached up to 8.08 mmol/g<inf>CeO₂</inf>. However, they showed an adverse impact on the carbon formation associated with methane cracking reaction. Fifteen successive ceria redox cycles with stable patterns in the δ and syngas production yield validated material stability. The maximum δ achieved during ceria reduction was up to 0.38, complete oxidation yield with either water or CO<inf>2</inf> was achieved, while the highest solar-to-fuel energy conversion efficiency reached 5.22% and the energy upgrade factor was in the range of 0.97–1.10.

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