Biomass Gasification Technology Research Articles

Thermal and Catalytic Cracking of Toluene Using Char from Commercial Gasification Systems

Tar formation hinders the development of biomass gasification technologies. The use of pyrolytic char as a catalyst for removing tar has been widely investigated; its large specific surface area and pores distribution make it a good candidate for the cracking of heavy hydrocarbons. The present work assesses the catalytic activity of char from a commercial gasifier. Thermal degradation tests in N2 and in CO2 proved that the char is suitable for high-temperature applications (catalytic cracking) and showed release of CO and H2, which might affect the catalytic performance of the char when used for tar removal applications. For inspecting the potential of the char for tar removal, toluene was chosen as model tar. Through GC-FID, toluene removal efficiency and the amount of benzene produced from its decomposition were evaluated. Tests up to 1273 K resulted in tar removal efficiencies as high as 99.0%, and empty reactor tests allowed for discerning the effects of thermal and catalytic cracking. The catalytic activity of the char was more pronounced at 1173 K, as char increased the toluene removal efficiency from 39.9% (empty reactor) to 60.3%. The results confirmed that gasification char, like pyrolytic char, has a high potential for catalytic tar removal applications.

Exploring the Conversion Mechanisms of Toluene as a Biomass Tar Model Compound on NiFe2O4 Oxygen Carrier

As a novel biomass gasification technology, chemical looping gasification (CLG) could in situ catalytically crack biomass tar by oxygen carrier (OC). This study compares the reactivity of different OCs (Al₂O₃, Fe₂O₃, NiO, NiO+Fe₂O₃, and NiFe₂O₄) to crack a biomass tar model compound (toluene) and preliminarily explores the reaction mechanisms of toluene cracked by NiFe₂O₄ OC. Among five OCs, NiFe₂O₄ with a homogeneous Fe/Ni dispersibility shows the best reactivity for toluene cracking with a toluene conversion and H₂ yield of 96.83% and 0.91 L/g, respectively. Additionally, on the basis of the dispersibility of active sites on the OC sample surface, the reactivity of the other four OCs to crack toluene shows the sequence NiO+Fe₂O₃ > Fe₂O₃ > NiO ≫ Al₂O₃. A large amount of carbon deposition, including amorphous carbon and graphitized carbon, is generated during toluene catalytic cracking, while the addition of steam significantly eliminates the carbon deposition. The NiFe₂O₄ OC shows a dual-function of in situ oxidation–catalysis during toluene cracking. A mechanism of four steps is proposed for the toluene cracking on OCs: (I) toluene cracking at high temperature, (II) reduction of OC, (III) generation of amorphous carbon deposition and (III′) formation of graphitized carbon, and (IV) elimination of carbon deposition.

Thermodynamic and economic evaluation of a novel configuration for sustainable production of power and freshwater based on biomass gasification

This paper presents a novel thermal cycle for renewable production of power and freshwater with the use of biomass gasification technology. For this purpose, a realistic simulation program is developed (in C# programming language) to predict the composition of synthesis gas produced in the gasifier. Using the proposed system, both power and water demand of a small city with 3000 people can be met without any fossil fuel consumption. So, the proposed system can help in reaching a sustainable future. This novel system is then compared with two conventional systems for the production of power and water. The first one is a conventional natural gas-based system without any heat integration and the second one is a natural gas-based system with heat integration. It is concluded that the novel proposed system will result in 5,267,800 m3 of natural gas saving per annum in comparison to the conventional system without heat integration. On the other hand, 4,211,300 m3 of natural gas per year is saved in comparison to the conventional system with heat integration. Economic results show that the levelized cost of produced power and water for the novel system are 0.11 $/kWh and 1.25 $/m3 respectively, and the period of return is 13.6. Additionally, a sensitivity analysis is performed to specify the impact of various thermodynamic and economic variables of the system on the final outputs. This research makes it possible to compare this renewable combined system with other conventional systems from thermodynamic and economic points of view.

Simulated biomass tar removal mechanism by a Quench Coupled with ADsorption Technology (QCADT)

Abstract Tar removal is a bottleneck in the smooth commercialization of biomass gasification technology. Based on introducing adsorption process into Quench Coupled with ABsorption Technology (QCABT) previously proposed by the author's group, Quench Coupled with ADsorption Technology (QCADT) has been developed to narrow this gap. Additionally, benzene and naphthalene, which are more similar to the real tar for containing aromatic ring structures, were adopted as light and heavy simulated tar, respectively. Also their removal behavior by QCADT was investigated. The results show that the removal mechanism of QCADT is similar to that of QCABT, except for the higher overall tar removal rate due to adsorption effect. Adsorbents with both micro- and narrow mesopores exhibit a better benzene removal performance, while narrow mesopores play dominant roles in naphthalene removal. Penetration adsorption loading of benzene and naphthalene on AC-1 can reach 0.38 g·g−1 and 0.34 g·g−1, respectively. The sawdust hardly has any tar removal effect. Combined micro- and meso-pores, will benefit both deep tar removal and large adsorption rate, providing a high tar removal efficiency.

Development of the forest waste gasification system with electricity production

The aim of this work is development of a technological scheme of gasification of biomass to generate electricity, as well as development of efficient circulating fluidized bed gasifier with heat exchanger. The paper deals with the existing technology of biomass gasification and the influence of thermal parameters on the composition of gasification products.

Autothermal CaO Looping Biomass Gasification for Renewable Syngas Production.

Biomass gasification is regarded as a promising alternative to fossil fuels for producing sustainable and clean value-added products. However, the challenges including low energy efficiency, CO2 emission, and ash agglomeration significantly delay the deployment of the technology. Herein, we first proposed a novel autothermal CaO looping biomass gasification (Auto-CaL-Gas) technology, in which CaO-based materials react with flue gas with a high concentration of CO2 (>30 vol %) to produce heat inside the gasifier, simultaneously providing energy for low-temperature biomass gasification using CO2 as a gasification agent. Upon use of this concept the syngas production exhibited a significant increase from 0.21 kg/h to 0.90 kg/h in the Aspen simulation results and more than 3-fold improvement in the experimental results.

A Comprehensive Literature Review of Thermochemical Conversion of Biomass for Syngas Production and Associated Challenge

The interest in the thermochemical conversion of biomass for producer gas production since last decade has increased because of the growing attention to the application of sustainable energy resources. Application of biomass resources is a valid alternative to fossil fuels as it is a renewable energy source. The valuable gaseous product obtained through thermochemical conversion of organic material is syngas, whereas the solid product obtained is char. This review deals with the state of the art of biomass gasification technologies and the quality of syngas gathered through the application of different gasifiers along with the effect of different operating parameters on the quality of producer gas. Main steps in gasification process including drying, oxidation, pyrolysis and reduction effects on syngas production and quality are presented in this review. An overview of various types of gasifiers used in lignocellulosic biomass gasification processes, fixed bed and fluidized bed and entrained flow gasifiers are discussed. The effects of various process parameters such as particle size, steam and biomass ratio, equivalence ratio, effects of temperature, pressure and gasifying agents are discussed. Depending on the priorities of several researchers, the optimum value of different anticipated productivities in the gasification process comprising better quality syngas production improved lower heating value, higher syngas production, improved cold gas efficiency, carbon conversion efficiency, production of char and tar have been reviewed.

Solid oxide fuel cell stack coupled with an oxygen-blown TwoStage gasifier using minimal gas cleaning

The coupling of biomass gasification and solid oxide cell technologies is very intriguing due to its high efficiency and flexibility potential. One of the key challenges in order to realize such a system design is a clean quality gas that can meet the strict requirements of the SOFC. This study presents the result of an experimental campaign with the TwoStage Viking biomass gasifier and a Topsoe Fuel Cell SOFC stack connected via a carbon filter and a desulphurizer. The stack is operated with both air- and O2CO2-blown product gas, at 700 °C and 800 °C, and tests without any gas cleaning was conducted. The study found electric efficiencies up to 40% at 69% fuel utilization and an 8–11% increase in power when raising the SOFC temperature to 800 °C. The O2CO2-blown product gas showed lower efficiencies due to lower CO performance in the SOFC. A preliminary 2-h test with no gas cleaning between the gasifier and SOFC, and a ≈1.5–2.8 ppm sulphur concentration showed no change in operational voltage. Hence the study finds that gasifier design can greatly simplify the demand for gas cleaning equipment.

Interaction of Ce-char catalyst and partial oxidation on changes in biomass syngas composition

Tars produced with syngas greatly restricted the industrial application of biomass gasification technology. In this study, various char-supported catalysts including Ce-char, Ni-char, Fe-char, K-char, and Ca-char were prepared by the wetness impregnation method. Catalytic activity of char-supported catalysts was investigated for syngas reforming during the partial oxidation process in a lab-scale gasifier. The char-supported catalysts were also characterized using Fourier transform infrared spectroscopy, XRD, Brunauer-Emmett-Teller theory, and scanning electron microscopy/energy dispersive spectroscopy. The novel catalyst, Ce-char, exhibited the best catalytic activity in tar removal among all the tested catalysts. At an optimum set of reaction parameters (a reaction temperature of 800 °C and 13% of air addition), the interaction of the Ce-char catalyst and partial oxidation reached a tar removal rate of 99.28% and a lower heating value of 8.55 MJ/Nm3 for syngas. Highly dispersed CeO2 as the active component was observed from the Ce-char catalyst. The Ce-char catalyst was verified to be a promising catalyst for syngas reforming even better than Ni-char.

Multi‐objective optimization of green urea production

AbstractThe availability of natural gas as feedstock for nitrogen fertilizer production continues to decline, while its price increases, encouraging the search for renewable feedstocks for the future green urea industry. Renewable feedstocks include waste biomass, hydrogen from solar PV‐electrolysis, and the combination of these feedstocks with natural gas. The selection of a green production strategy is a critical step in the trade‐off between economic and environmental considerations. The aim of this work was to propose a green urea production strategy using a multi‐objective optimization (MOO) model to minimize production costs and environmental impacts by considering the future cost development of technologies and feedstock price for each technology in the time frame of 2020‐2050. The results show that green urea production can reduce production costs and greenhouse gas emissions, compared to conventional urea production. Biomass gasification technology fulfills the minimum requirements for production cost and CO2 emissions from 2020 to 2035 and combined biomass gasification‐PV electrolysis without battery technology is the optimum process from 2040 to 2050.

Techno-Economic and Life Cycle Impacts Analysis of Direct Methanation of Glycerol to Bio-Synthetic Natural Gas at a Biodiesel Refinery

An economic and environmental feasibility study were carried out on the thermochemical conversion of glycerol to medium methane content biological synthetic natural gas (bio-SNG). A plant that processed 497 kg·h−1 of glycerol to bio-SNG was modelled as an on-site addition to a soybean biodiesel plant based in Missouri (USA) that produced 30 million litres of soybean biodiesel per year. Assuming the glycerol contained only 80 wt% free glycerol, the bio-SNG could substitute up to 24% of the natural gas at the soybean biodiesel plant. The discounted cash flow analysis showed it was possible to generate positive NPVs and achieve internal rates of return within the hurdle rate (12%) for biomass gasification technologies. From the environmental analysis it was found that the bio-SNG could reduce global warming potential by 28% when compared to conventional natural gas in the USA and translates to roughly 7% reduction in biodiesel natural gas emissions, if the maximum 24% of natural gas were to be substituted by bio-SNG. The work highlights the potential to divert waste glycerol to an onsite energy vector at soybean biodiesel plants with minimal change to the main biodiesel production process and potential reductions to soybean biodiesel global warming potential.

The modern state of wood biomass gasification technologies and their economic efficiency

Abstract This paper presents an overview of state-of-the-art in single- and multistage wood biomass gasification technologies and assesses their economic efficiency. We compare the cost of electricity generated through the use of different types of fuel (gas, diesel, coal, wood chips and wood pellets) and show that the most promising technology for processing biomass is multi-stage gasification.

Characterization of Coal Bottom Ash &its Potential to be used as Catalyst in Biomass Gasification

Abstract A potential renewable and sustainable green energy source is biomass gasification. The role of catalyst is significant in biomass gasification technology to overcome associated problems like tar reduction and to make it economically viable. Several catalysts like dolomite, alkaline metal, nickel, etc. have been incorporated which plays an essential role in higher product yield and tar reduction but holds problems like inactivity, regeneration, and cost. In this study, physio-chemical properties of coal bottom ash have been studied for its application as a catalyst in biomass steam gasification. The characterization of coal bottom ash comprises of surface morphology analysis, existing elements, pore size, and volume, as well as surface area and bulk density, were reported. The results showed that elements like Si, Fe, Al, Ca and Mg were present in coal bottom ash which have been previously used as a catalyst in biomass gasification. The pore diameter of coal bottom ash is 4 nm, the specific pore volume is 0.01474 cm3/g, specific surface area of 17.64 m2/g which lies it in mesoporous classification. Also, it is observed that CaO mineral exists in coal bottom ash support in reducing the CO2 gas while improving syngas yield. The presence of SiO2 shows that it can use as bed material while Fe2O3 improves the tar reduction in the product gas whereas CaO assists to capture CO2 in the process whereas, alumina resist sintering of metal catalyst. Coal bottom ash is economically viable due to abundance and low cost. Based on its composition (presence of Ca, Mg and other alkali metal) as analyzed .it can be used as an alkaline metal catalyst.

NiCo@NiCo phyllosilicate@CeO2 hollow core shell catalysts for steam reforming of toluene as biomass tar model compound

Developing sintering and carbon resistant tar removal catalysts is crucial for biomass gasification technology. Herein, for the first time, NiCo@NiCo phyllosilicate@CeO2 hollow core shell catalysts have been designed for steam reforming of toluene (SRT) as the biomass tar model compound. They show both good catalytic activity and stability within 45 h of time on stream due to their high sintering resistance of NiCo because of the strong interactions between NiCo and CeO2, high metal exposure as a result of the high specific surface area, high surface metal concentration as well as the high oxygen vacancies as evidenced from the H2-Temperature-programmed reduction (H2-TPR), H2 chemisorption and X-ray photoelectron spectroscopy (XPS) characterizations respectively. Additionally, the synergistic effect between Ni and Co further improves their carbon resistant property. By comparison, Co@Co phyllosilicate@CeO2 catalysts perform the lowest toluene conversion and stability mainly due to their structural instability during reaction resulting from their high Si/Co ratio, leading to their low specific surface area and Co exposure. The outstanding SRT performance of NiCo@NiCo phyllosilicate@CeO2 catalysts indicates their promising application for steam reforming of biomass tar reaction.

Techno-Economic Analysis of Biomass Energy Utilization through Gasification Technology for Sustainable Energy Production and Economic Development in Nigeria

Nigeria has not been able to provide enough electric power to her about 200 million people. The last effort by the federal government to generate 6000 MW power by the end of 2009 failed. Even with the available less than 6000 MW of electricity generated in the country, only about 40% of the population have access to the electricity from the National Grid, out of which, urban centers have more than 80% accessibility while rural areas, which constitute about 70% of the total population, have less than 20% of accessibility to electricity. This paper addresses the possibility of meeting the energy demand in Nigeria through biomass gasification technology. The techno-economic analysis of biomass energy is demonstrated and the advantages of the biomass gasification technology are presented. Following the technical analysis, Nigeria is projected to have total potential of biomass of about 5.5 EJ in 2020 which has been forecast to increase to about 29.8 EJ by 2050. Based on a planned selling price of $0.727/kWh, the net present value of the project was found to be positive, the cost benefit ratio is greater than 1, and the payback period of the project is 10.14 years. These economic indicators established the economic viability of the project at the given cost. However, economic analysis shows a selling price of $0.727/kWh. Therefore, the capital investment cost, operation and maintenance cost, and fuel cost can be reduced through the development of the gasification system using local materials, purposeful and efficient plantation of biomass for the energy generation, giving out of financial incentives by the government to the investors, and locating the power plant very close to the source of feedstock generation.

Evaluating removal of tar contents in syngas produced from downdraft biomass gasification system

ABSTRACTBiomass gasification is a process of converting solid biomass ingredients into a combustible gas which can be used in electricity generation. Regardless of their applications in many fields, biomass gasification technology is still facing many cleaning issues of syngas. Tar production in biomass gasification process is one of the biggest challenges for this technology. The aimed of this study is to evaluate the tar contents in syngas produced from wood chips and corn cobs as a biomass fuel and tar removal efficiency of different cleaning units integrated with gassifier. Performance of different cleaning units, i.e., cyclone separator, wet scrubber, biomass filter, and auxiliary filter was tested with two biomass fuels. Results of this study reported that wood chips produced less tar 6,600 mg/Nm3 as compared to corn cobs 7,500 mg/Nm3 in biomass reactor stage before cleaning. After passing through the whole cleaning system, the tar concentration in case wood chip reduced from 6,600 to 112 mg/Nm3, while in case of corn cob from 7,500 to 220 mg/Nm3. Overall tar removal efficiencies of cyclone separator, wet scrubber, biomass filter and auxiliary filter was noted as 72%, 63%, 74%, 35 %, respectively.

Hybrid life-cycle assessment for energy consumption and greenhouse gas emissions of a typical biomass gasification power plant in China

Among biomass energy technologies which are treated as the promising way to mitigate critical energy crisis and global climate change, biomass gasification plays a key role given to its gaseous fuels especially syngas for distributed power plant. However, a system analysis for the energy saving and greenhouse gas emissions abatement potentials of gasification system has been directed few attentions. This study presents a system analysis that combines process and input-output analyses of GHG emissions and energy costs throughout the full chain of activities associated with biomass gasification. Incorporating agricultural production, industrial process and wastewater treatment which is always ignored, the energy inputs in life cycle are accounted for the first commercial biomass gasification power plant in China. Results show that the non-renewable energy cost and GHG emission intensity of the biomass gasification system are 0.163 MJ/MJ and 0.137 kg CO2-eq/MJ respectively, which reaffirm its advantages over coal-fired power plants in clean energy and environmental terms. Compared with other biomass energy processes, gasification performs well as its non-renewable energy cost and CO2 intensity are in the central ranges of those for all of these technologies. Construction of the plant is an important factor in the process's non-renewable energy consumption, contributing about 44.48% of total energy use. Wastewater treatment is the main contributor to GHG emissions. The biomass gasification and associated wastewater treatment technologies have critical influence on the sustainability and renewability of biomass gasification. The results provide comprehensive analysis for biomass gasification performance and technology improvement potential in regulating biomass development policies for aiming to achieve sustainability globally.

Techno-economic comparative analysis of Biomass Integrated Gasification Combined Cycles with and without CO2 capture

Biomass Integrated Gasification Combined Cycle (BIGCC) power system is a potential application of biomass gasification technology to control CO2 emissions from power generation processes. Nevertheless, there is no study of BIGCC systems that provides detailed techno-economic comparative among its different technological alternatives. This study provides the techno-economic comparative analysis of eight BIGCC system designs that include the technology options of the biomass gasification, the power generation, and the CO2 emission control. Results show that the Levelized Cost of Electricity (LCOE) of these systems is ranged from 13.1 ¢/kWh to 25.9¢/kWh. For current designs, the Selexol CO2 removal technology is more economical than the MEA CO2 capture process. Furthermore, when the biomass price is lower than 10 $/ton, the air gasification BIGCC systems can compete with the current electricity generation technology, whereas when the CO2 emission price is higher than 90 $/ton, the additional CO2 Capture and Storage technology has the potential to reduce the LCOE of BIGCC systems. Moreover, the sensitivity analysis estimates the impacts of other key economic parameters on the LCOE and Monte Carlo method is used to show the uncertainty of simulation.

A Review of Technologies for Multistage Wood Biomass Gasification

Currently, small-scale distributed power generation is being intensively developed in Russia and abroad. Given the rise in the rates for the electric and thermal energy, the development of new territories, and the technical infeasible connection to the power supply system, one of the most promising variants of supplying isolated consumers with power is the application of wood biomass gasification technologies. Analysis of the studies in this sphere shows that considerable attention is paid to enhancing the gasification efficiency and ensuring the purity of the gas. These problems are solved using multistage gasification technology. This technology involves the pyrolysis and gasification in separated zones of the gasifier or individual interconnected reactors, which enables achieving the optimal conditions for the conversion of biomass at every separate stage. The major advantage of multistage gasifiers is the production of synthesis gas with a low content of tar. The article represents a review of technologies for multistage wood biomass gasification and comparison of the relevant gasifiers of various types; the basic single-stage and multistage wood biomass gasification technologies are examined and their technical characteristics and examples of their commercial implementation are provided. Analysis of the current situation shows that predominantly foreign multistage wood biomass gasification technologies/plants have found practical application. These technologies allow the produced syngas to be directly used in internal combustion engines and gas turbines without employing expensive auxiliary detarring plants.

Characterization of combined Fe-Cu oxides as oxygen carrier in chemical looping gasification of biomass

Chemical looping gasification (CLG) of biomass is an innovative biomass gasification technology, where oxygen carrier (OC) has the effects of oxygen supply, heat transfer and catalyst for syngas production. In order to integrate the synergistic effect between Fe and Cu oxides, a novel combined OC containing Fe2O3 and CuO was produced for biomass gasification and investigated in a batch fluidized bed reactor in this work. At first, an OC with 50 wt.% Fe2O3 and 10 wt.% CuO (Fe50Cu10) was selected as the representative OC to evaluate the superiority of combined OC. The mono-metallic OC of CuO is unsuitable as oxygen carrier in the CLG of biomass due to its too low syngas yield, although CuO can greatly accelerate biomass gasification process. In addition, combined Fe-Cu oxides OC is also superior to mono-metallic OC of Fe2O3 at enhancing carbon conversion efficiency on the premise that syngas yield tended to be close. Then the blending ratio of Fe/Cu was optimized and Fe50Cu10 had been proven to be the optimal combined Fe-Cu oxides OC in CLG. Next, the influences of the factors including gasification temperature, steam mole fraction and O/C ratio on the performance of Fe50Cu10 were investigated. 900 °C is the best temperature for gasification and higher team mole fraction gave rise to higher carbon conversion efficiency and syngas yield, while O/C ratio was somewhat different. The optimal O/C ratio was deemed to be 0.78. Besides, 10 redox cycles were conducted to investigate the stability of combined OC reactivity. The combined OC after 3 cycles performed worst reactivity, while better performance was demonstrated after 7–10 cycles. Based on the analysis of SEM-EDX, it was found that sintering caused by Cu atomic was the main cause of the reactivity decline. In addition, it was inferred that the distribution of Cu atomic in the combined OC was more uniform with the cycle number.