Solar-driven Gasification Research Articles

Green iron and syngas production via continuous solar-driven agricultural waste biomass gasification combined with iron(III) oxide reduction

The production of renewable synthetic fuels and chemicals from solar energy and agricultural waste biomass is considered. Solar thermochemical conversion processes offer a promising pathway to a sustainable fuel economy and green chemical industry. This study investigates the continuous solar-driven gasification of agricultural biomass (betel nut waste) combined with iron oxide (Fe2O3) reduction to produce carbon-neutral syngas and green metallic iron in a single process. A thermodynamic analysis of the system was initially conducted to predict the distribution of equilibrium products. Then, on-sun continuous processing was experimentally carried out under different operating conditions, including betel/Fe2O3 molar ratios (0.56–1.5) and temperatures (900–1200 °C) to evaluate the process feasibility and reliability. As a result, solar gasification of betel nut waste combined with Fe2O3 reduction performed exceptionally well with continuous reactant particles feeding, demonstrating a feasible pathway for producing green iron and high-quality syngas. The maximum syngas yield reached 63.3 mmol/gdry_betel, approaching its theoretical value, and high-purity Fe was simultaneously produced. The process demonstrated high efficiency, with maximum carbon conversion approaching 98 %, energy upgrade factor up to 1.26, and solar-to-fuel energy conversion efficiency up to 14.4 %, highlighting remarkable conversion performance of biomass and solar energy to chemicals.

Solar-driven gasification for syngas production at low temperatures using a rotary hybrid porous media reactor

Solar-based technologies play a crucial role in the energy transition towards a green circular economy. This work investigates the solar-driven steam gasification of carbon char particles at low temperatures using an indirectly irradiated rotary hybrid porous media reactor. The solar concentration system consists of a heliostat and parabolic dish with a focus on the emitter plate located at the bottom of the reactor, allowing allothermal conditions for hydrogen (H2) and syngas production. The hybrid bed is composed of carbon and alumina particles randomly mixed in a 50/50 proportion in mass. Three sets were tested varying rotation speed of the unit, i.e., Set A (0 rpm), Set B (15 rpm), and Set C (20 rpm). Numerical simulations were performed using a one-dimensional model assessing mass, energy and chemical conservation equations, considering a semi-global kinetic scheme, including three homogeneous and four heterogeneous chemical reactions. The optical design configuration of the solar system, in addition to the high heat recirculation enhanced by the rotation of the reactor, allowed maximum temperatures of 662 K (outer surface) and 573 K (reaction chamber). At this low-temperature range, a good agreement between numerical simulations and experiments was achieved, observing a H2/CO ratio of 0.088 (Set B) and 0.163 (Set C), representing a 5.7% and 3.1% deviation, respectively. Numerical results show an increase in the temperature would lead to a higher H2/CO ratio production. Further studies are necessary to assess hydrogen and syngas production under these operating conditions at high temperatures.

Applying the solar solid particles as heat carrier to enhance the solar-driven biomass gasification with dynamic operation power generation performance analysis

Solar-driven biomass gasification is a promising technology to improve the utilization efficiency of solar energy and biomass, which also enhances the thermochemical storage and the subsequent stable utilization. Whereas, the intermittence of solar energy deteriorates the stability and continuity of the thermochemical reaction process, which limits the efficient conversion of the reaction. In this regard, this work proposes a new solar-driven biomass gasification technology based on solid particle heat carrier. Different from the direct solar-driven gasification, solid particles are performed as medium to receive the concentrated solar radiation energy and transfer energy to biomass feedstocks. In addition, the combined power generation scenario is adopted to evaluate the thermodynamics and economics of the technology. The integration of solid particle heat storage, the system dispatch and stable operation will be further enhanced. Results show that under the optimal condition, the system maximum thermal and exergy efficiencies are increased by 12.94% and 12.51%, respectively. Considering the system off-design operation, with the evaluated typical periods of four seasons, the averaged power generation efficiency is increased by 5.16%, with the highest efficiency improvement of 9.41% occurring in the typical winter days. With the change of receiver price and biomass price, the maximum decline of levelized cost of electricity reaches to 17.6%, which presents the favorable economic benefits. As a new solar thermochemical technology, this technology exhibits competitive characteristics, significantly improving the utilization efficiency of solar and biomass energy.

Solar-driven biomass steam gasification by new concept of solar particles heat carrier with CPFD simulation

Solar-driven biomass gasification is a promising solar thermochemical technology to produce green H2-enriched syngas, and contribute to solar energy upgrade and efficient conversion. Whereas, the continuous and stable operation of solar-driven biomass gasification is challenging due to the non-uniform concentration of solar flux and its fluctuating nature. In this regard, a novel concept of solar-driven gasification is proposed, using solar-heated particles as the heat carrier, and biomass steam gasification in a fluidized bed reactor is numerically investigated based on the computational particle fluid dynamics (CPFD) model. The complex distributions of gas and particle phases, as well as the effects of operation parameters on syngas species are comprehensively analyzed. Results indicate that the biomass material and solar-heated particles can be well-mixed through continuous feeding, and the internal heat transfer and gasification kinetics are enhanced. The mole fraction of H2 and CO in the produced syngas reach to 50.86% and 18.97% under the benchmark operating condition. By using the high-temperature quartz sand as the solar particles heat carrier, the long-term and continuous operation of the endothermic gasification process can be achieved. The newly developed solar-driven biomass gasification method provides a promising approach to mitigate the impact of the fluctuating solar irradiation and enhance the operational flexibility of gasification process.

Continuous solar-driven gasification of oil palm agricultural bio waste for high-quality syngas production

Empty fruit bunch (EFB) from oil palm is a solid agricultural bio-waste obtained from the edible oil process. Continuous solar-driven gasification of EFB offers a bright carbon–neutral avenue to convert both EFB bio-waste and renewable solar energy into sustainable and clean syngas. High-temperature concentrated solar heat is used to provide the reaction enthalpy, and therefore biomass waste feedstock is entirely dedicated to produce hydrogen and carbon monoxide (syngas). Solar energy is stored as a high-quality syngas and can be easily transported as a convertible and dispatchable chemical form. In this study, the performance of continuous steam gasification of EFB, fully powered by concentrated solar heat, was experimentally investigated in a solar gasification reactor. Experiments were carried out with continuous EFB biomass injection to evaluate the influence of temperature (1100–1300 °C) and biomass feeding rate (0.5–1.8 g/min). As a result, syngas yields and reactor performance were substantially enhanced by rising the EFB feeding rate and gasification temperature. An optimal EFB biomass feeding rate enabling maximum gasification performance was found to be 1.4 g/min at 1300 °C and 1.0 g/min at 1200 °C. Carbon conversion approaching 97%, energy upgrade factor of 1.38, and solar-to-fuel energy conversion efficiency up to 20% were demonstrated. Finally, the maximum syngas yield was found to be 81.1 mmol/gdry biomass at 1300 °C (with H2 and CO as the main constituents), closely approaching the maximum theoretical expected value reached at thermodynamic equilibrium (85.2 mmol/gdry biomass). Combining concentrated solar energy and biomass waste gasification was shown to be a promising and sustainable pathway toward waste valorization into carbon–neutral solar fuels.

Coal gasification process driven by concentrated solar radiation for carbon neutralization: Reaction and energy characteristics

Solar-driven gasification products for chemical feedstock are one of the effective means to utilize coal in a low-carbon and resourceful way. However, few studies on the reaction and energy characteristics are based on experimental data of concentrated solar coal gasification. This study designed a novel experimental solar radiation gasification thermogravimetric device. An energy model of a solar radiation dish thermochemical conversion system was also developed. Compared to indirect radiation, direct radiation has a 10 % higher carbon conversion rate, an increased energy upgrade factor (up to 0.86), and a 38.5 % increase in energy conversion efficiency. Furthermore, we investigate direct radiation-catalyzed gasification to assess the effects of different types and ratios of catalysts. The results showed that the catalytic effect of K2CO3 was better than that of Na2CO3, which would improve the energy conversion efficiency by 4.8 %. For K2CO3, the efficiency was increased by 14.1 % through increasing the doping ratio from 5 % to 10 %. Meanwhile, this study analyzed the reaction kinetics of direct radiation-catalyzed gasification. Finally, we constructed a solar concentrating radiation dish thermochemical conversion system model based on the experimental data. We found that the system energy efficiency in the direct radiation form was 15.3 % higher than that in the indirect radiation form; besides, adding the catalyst in the direct radiation form increased the energy efficiency by 23.8 %. We also found that the gasifier exergy efficiency in direct radiation catalyst gasification was 29.7 %, and that of indirect radiation gasification was 7.23 %. The monthly solar exergy distribution follows the solar radiation closely. The results guide the chemical process of solar thermal conversion.

Solar-driven gasification in an indirectly-irradiated thermochemical reactor with a clapboard-type internally-circulating fluidized bed

A 7-kWth indirectly irradiated solar gasifier with a clapboard-type internally circulating fluidized bed was developed and conducted experimentations under concentrated solar radiation. The solar CO2 gasification of charcoal produced by low-temperature pyrolysis was examined under a 28-kWe high-flux solar simulator considering different operating conditions. The effects of CO2:C and feedstock mass on the key performance indicators e.g. the carbon conversion, energetic upgrade factor, and solar conversion efficiency were investigated by using alumina granules as an inert bed material. The first-hand, reproducible experimental data indicated the highest values of the average carbon conversion of 0.53 ± 0.04, energetic upgrade factor of 0.883 ± 0.03, solar conversion efficiency of 5.3 ± 0.6% were achieved under the operating conditions of 80 g charcoal, 1.5 kg alumina particles, and 2 L/min CO2. The feedstock mass significantly affected the solar conversion efficiency but no notable effect on the energetic upgrade factor was observed. The solar conversion efficiency can be significantly improved via fully replacing inert alumina particles by feedstock, adding a continuous feeder, and optimizing the superficial velocity to minimize particle entrainment.

Biomass Gasification in an Innovative Spouted-Bed Solar Reactor: Experimental Proof of Concept and Parametric Study

Solar thermochemical gasification of lignocellulosic biomass promises a new path for the production of alternative fuels as well as storage and transport of solar energy as a convertible and transportable fuel. The use of concentrated solar energy as the external heat source for the high-temperature reaction allows producing high-value syngas with both higher energy conversion efficiency and reduced cost of gas cleaning and separation, while saving biomass feedstock. A newly designed solar reactor based on the principle of spouted bed reactor was used for continuous solar-driven gasification of biomass particles. The reliable operation of this 1.5 kW reactor was experimentally demonstrated under real solar irradiation using a parabolic dish solar concentrator. Several types of biomass particles were continuously fed in the reactor at temperatures ranging from 1100°C to 1400°C. The injected particles consisted of beech wood or a mix of resinous wood with size ranging from 0.3 mm to 2 mm. The aim of this st...

A review of the state-of-the-art in solar-driven gasification processes with carbonaceous materials

Gasification of carbonaceous feedstock with process heat derived from concentrated solar irradiation has been shown as a promising renewable pathway towards producing synthesis gas (mixtures of H2/CO and some CO2). The carbonaceous feedstock is upgraded in calorific content equal to the enthalpy change of the endothermic reaction, which results in the net storage of solar energy in a chemical form. The process is carbon-neutral when biomass is used and the feedstock is transformed into a fuel with applications to more efficient processes (e.g., Air-Brayton cycle), and the resulting syngas can be converted to liquid hydrocarbon fuels via know catalytic routes. A comprehensive summary is provided of the state-of-the-art in solar gasification, including thermodynamic and kinetic analyses and thermochemical reactor modeling, fabrication and testing for a range of carbonaceous feedstocks.

Solar-driven pyrolysis and gasification of low-grade carbonaceous materials

Three low-grade carbonaceous materials from biomass (Scenedesmus algae and wheat straw) and waste treatment (sewage sludge) have been selected as feedstock for solar-driven thermochemical processes. Solar-driven pyrolysis and gasification measurements were conducted directly irradiating the samples in a 7 kWe high flux solar simulator and the released gases H2, CO, CO2 and CH4 and the sample temperature were continuously monitored.Solar-driven experiments showed that H2 and CO evolved as important product gases demonstrating the high quality of syngas production for the three feedstocks. Straw is the more suitable feedstock for solar-driven processes due to the high gas production yields. Comparing the solar-driven experiments, gasification generates higher percentage of syngas (mix of CO and H2) respect to total gas produced (sum of H2, CO, CO2 and CH4) than pyrolysis. Thus, solar-driven gasification generates better quality of syngas production than pyrolysis.

Solar thermochemical gasification of wood biomass for syngas production in a high-temperature continuously-fed tubular reactor

Biomass gasification is an attractive process to produce high-value syngas. Utilization of concentrated solar energy as the heat source for driving reactions increases the energy conversion efficiency, saves biomass resource, and eliminates the needs for gas cleaning and separation. A high-temperature tubular solar reactor combining drop tube and packed bed concepts was used for continuous solar-driven gasification of biomass. This 1 kW reactor was experimentally tested with biomass feeding under real solar irradiation conditions at the focus of a 2 m-diameter parabolic solar concentrator. Experiments were conducted at temperatures ranging from 1000 °C to 1400 °C using wood composed of a mix of pine and spruce (bark included) as biomass feedstock. This biomass was used under its non-altered pristine form but also dried or torrefied. The aim of this study was to demonstrate the feasibility of syngas production in this reactor concept and to prove the reliability of continuous biomass gasification processing using solar energy. The study first consisted of a parametric study of the gasification conditions to obtain an optimal gas yield. The influence of temperature, oxidizing agent (H2O or CO2) or type of biomass feedstock on the product gas composition was investigated. The study then focused on solar gasification during continuous biomass particle injection for demonstrating the feasibility of a continuous process. Regarding the energy conversion efficiency of the lab scale reactor, energy upgrade factor of 1.21 and solar-to-fuel thermochemical efficiency up to 28% were achieved using wood heated up to 1400 °C.

Solar-driven gasification of carbonaceous feedstock—a review

Given the future importance of solid carbonaceous feedstocks such as coal, coke, biomass, bitumen, and carbon-containing wastes for the power and chemical industries, gasification technologies for their thermochemical conversion into fluid fuels are developing rapidly. Solar-driven gasification, in which concentrated solar radiation is supplied as the energy source of high-temperature process heat to the endothermic reactions, offers an attractive alternative to conventional autothermal processes. It has the potential to produce high-quality synthesis gas with higher output per unit of feedstock and lower specific CO2 emissions, as the calorific value of the feedstock is upgraded through the solar energy input by an amount equal to the enthalpy change of the reaction. The elimination of an air separation unit further facilitates economic competitiveness. Ultimately, solar-driven gasification is an efficient means of storing intermittent solar energy in a transportable and dispatchable chemical form. This review article develops some of the underlying science, examines the thermodynamics and kinetics of the pertinent reactions, and describes the latest advances in solar thermochemical reactor technology.