Gasification Options Research Articles

Comparative Feasibility and Environmental Life Cycle Assessment of Cotton Stalks Gasification and Pyrolysis

In a circular economy, significant emphasis is given to the energetic valorization of agricultural byproducts. Cotton stalks are suitable as a feedstock for the production of bioenergy due to their high energy content. This study’s main focal areas are the economic viability and environmental implications of a system that can gasify or pyrolyze 25,500 tons of cotton stalk annually. To learn more about how gasification and pyrolysis affect the environment, a life cycle assessment (LCA) was conducted. This analysis evaluates the whole value chain and covers all stages of the cotton supply chain from cradle to gate, including production, harvest, transportation, and utilization. According to the findings, both systems exhibit economic viability, generating sizable profits and having quick payback times. However, despite its larger initial expenditure of EUR 2.74 million, the pyrolysis unit ends up being the better option because it has a payback period of 1.58 years, a return on investment (ROI) of 58% and a net present value (NPV) of EUR 21.5 million. Gasification is still an economically attractive alternative with a lower initial investment (EUR 1.81 million), despite having a lower ROI (36%) and NPV (EUR 10.52 million), as well as a longer payback period (2.41 years). However, the environmental implications of the gasification option are generally higher than those of pyrolysis. The impacts of gasification on fossil depletion (FDP) were estimated to be 5.7 million kg oil eq., compared to 5.3 million kg oil eq. for pyrolysis. Similarly, gasification resulted in 41.55 million kg U235 eq. and pyrolysis in 41.5 million kg U235 eq. related to impacts on ionizing radiation (IRP_HE). Other impact categories that emerge as the most important are freshwater eutrophication (FEP) and marine eutrophication (MEP).

Superstructure optimisation of blended-biomass hybrid poly gasification and utilisation system

Renewable fuel generation and reducing reliance on fossil fuels are essential components of sustainable development. Manufacturing and use of petrochemicals are such an important economic pillar of contemporary civilisation. Therefore, there is a strong incentive to allocate alternative production pathways in order to conserve scarce resources. In order to minimise global emissions, it is also necessary to utilise environment wastes to generate value-added goods. This study demonstrates the sustainability assessment of various biomass gasification utilisation strategies developed through the poly-generation process. The superstructure network, which consists of different biomass feedstock (sources) and prospective uses (sinks) among the various gasification alternatives (pools), is examined to find the most cost-effective and ecologically beneficial production routes. Superstructure optimisation aids decisions on biomass feedstock mixing and subsequent utilisation, while taking both economic and environmental concerns into account. The results indicated the importance of biomass feedstock blending in enhancing the profitability of the process and lowering the requirement of gasifying agents. The findings indicated the domination of the power generation technique at 95.9% for oxygen gasification and methanol production for both oxygen/steam and steam-only gasification options at 92.5% when economic objective is considered. However, when the environmental objective is considered, urea generation turned to dominate the utilisation allocation at 94.9% for oxygen gasification, and methanol dominated the allocation at 92.5% for oxygen/steam and steam-only gasification options. Nevertheless, when both objectives are considered concurrently, urea dominated the strategies in all scenarios with a varying allocation of 38%–95%. The former solution maximiser the net profit at 0.124 $/kg biomass, and minimised net emissions at 0.58 kg CO2/kg biomass. Additionally, the study highlights the excellence of steam-only gasification over oxygen/steam and oxygen-only gasification options in delivering value-added products with higher profits and lower emissions.

The role of biomass gasification in the future flexible power system – BECCS or CCU?

In this work we study if biomass gasification for production of advanced biofuels can also play a role in managing variability in the electricity system. The idea is a CCU/power-to-gas concept to enhance methane production from biomass gasification. The suggested process is flexible in that CO2 not used for methane production can be stored through a BECCS concept that implies negative GHG emissions. For this purpose, rigorous models of three different gasification process configurations were simplified through surrogate modeling and integrated into a dynamic optimization model of regional electricity systems. The results show the diverse advantages of flexible operation between CCU and BECCS and that it is economically beneficial for the system to invest in gasification at the investigated levels of CO2 charge. The gasification option also provides value for low-priced electricity and thus stimulate increased investments in renewable electricity generation, which indicates the importance of considering geographical diversities in the assessment and highlights the importance of studying this type of concept with a time-resolved model. It is clear that the BECCS option is the most used, however, the limited quantities of CO2 used for the CCU option has a large impact on the investments made in the electricity system.

The Role of Biomass Gasification in the Future Flexible Power System – BECCS or CCU?

In this work we study if biomass gasification for production of advanced biofuels also can play a role in managing variability in the electricity system. The idea is a CCU/power-to-gas concept to enhance methane production from biomass gasification. The suggested process is flexible in that CO2 not used for methane production can be stored through a BECCS concept that implies negative GHG emissions. For this purpose, rigorous models of three different gasification process configurations were simplified through surrogate modeling and integrated into a dynamic optimization model of regional electricity systems. The results show the diverse advantages of flexible operation between CCU and BECCS and that it is economically beneficial for the system to invest in gasification at the investigated levels of CO2 charge. The gasification option also provides value for low-priced electricity and thus stimulate increased investments in renewable electricity generation, which indicates the importance of considering geographical diversities in the assessment and highlights the importance of studying this type of concept with a time-resolved model. It is clear that the BECCS option is the most used, however, the limited quantities of CO2 used for the CCU option has a large impact on the investments made in the electricity system.

Process development of sustainable biorefinery system integrated into the existing pulping process

The change of paper consumption trend may jeopardize the future of pulp and paper industry. This work aims to design and develop the integrated network of biochemical and biofuel productions into existing pulp mills for sustainable purposes. The systematic methodology aided by computation tools is undertaken using the three-stage approach including process synthesis, design and innovation. Previously, the optimal technologies of the biorefinery-integrated pulping processes were successfully determined in the synthesis stage providing the highest cost-effective incorporation; 48 million USD/year of profit was estimated according to the integration of succinic acid and dimethyl ether productions into the soda pulping process. Herein, the process designs of the integrated processes were performed followed by evaluations of the process performances and identifications of the hot spots and targets for establishments of the innovations.In this work, the biomass gasification option is designed and implemented to enhance the material and energy utilizations in the previously determined biorefinery-integrated pulping processes. Electricity and biofuel are produced and sold, which contributes positively to the economic and environmental impacts of these processes. The hot spots and targets are subsequently identified prior to the innovation stage. According to this stage, the cleaner alternatives that implements the CO2 utilization via methanol synthesis and solar cell installations are selected in order to minimize the CO2 emission. A net CO2 reduction of 42% is achieved when the cleaner alternatives are applied. Accordingly, these biorefinery-integrated innovations are not only conducive to the enhanced sustainability of existing pulp mills but also adaptive in response to the change of paper consumption trend.

Environmental-economic evaluation of sugar cane bagasse gasification power plants versus combined-cycle gas power plants.

Approximately 2.4 million tons of bagasse are produced each year in Iran, most of which are currently treated as waste adding to serious environmental concerns. Application of bagasse for energy production is a sustainable solution to supply the required energy within the sugar refineries and export the surplus electricity to the grid. Currently, the energy demand in Iranian sugar mills is mainly supplied by fossil fuels (natural gas or mazut). Bagasse fluidized bed and fixed bed gasification plants would respectively lead to save 59,250 and 21,750 tons of CO2 annually, compared to gas power plants of the same scale. The present study aims to compare the environmental economic analysis of electricity generation in 10-MW gas-fired power plants with that electricity generation in bagasse gasification plants (with fluidized bed and fixed bed reactors) exemplarily in Iran. The bagasse fluidized bed gasification option (with IRR of 28.6%) showed the most promising economic viability compared to bagasse fixed bed gasification and gas power plant cases with IRR values of 25.09 and 21.94%, respectively. Furthermore, bagasse gasification options were potentially characterized by a better environmental performance compared to fossil-fuelled options. On the other hand, the obtained levelised cost of electricity at gas power plants (2 cents/kWh) was lower than the global range and lower than bagasse gasification cases (7-9 cents/kWh). The results revealed the vital need of biomass power plants to governmental support in order to compete with fossil power plants by participation of private sector.

Implementation of waste-to-energy options in landfill-dominated countries: Economic evaluation and GHG impact

The economic and environmental impact of several waste-to-energy (WtE) schemes to produce electricity from municipal solid waste (MSW) refuse is evaluated and compared with landfill disposal. Both incineration and gasification alternatives are considered. The gasification option includes three different configurations: (1) a fluidized bed gasifier (FBG) with internal combustion engine (ICE), (2) a FBG with organic Rankine cycle (ORC) and (3) a grate gasifier with steam Rankine cycle (SRC). The study is primarily applied to regions where the management system is based on Mechanical Biological Treatment (MBT) plants, generating a large share of refuse (>70%), which is currently landfilled. The specific case of Andalusia, a region in the south of Spain with 23 MBT plants distributed over a region of 87.000 km2, where about 80% of municipal solid waste (MSW) is currently landfilled, is taken as main reference; thereafter, the study is further extended to preliminary assess other regions of some European landfill-dominated countries with similar characteristics. The results show that both incineration and gasification improve landfill disposal, contributing favorably to greenhouse gas (GHG) reduction and fulfilling EU environmental regulations, although the three gasification options analyzed yield lower GHG emissions than incineration. In addition, gasification enables better integration of WtE into existing MBT plants, especially in the particular case of Andalusia, where MBT plants are widespread on the region, making it a more promising option than incineration, which is mainly based on large centralized plants, and less socially accepted. From the options analyzed, the WtE scheme based on FBG with ICE gives the highest profitability for a given gate fee, due to much higher electrical efficiency. However, FBG with ORC seems to be a better option in the short-term for landfill-dominated countries, due to its higher technical reliability and the low gate fee currently available in these countries.

Environmental assessment of energy generation from agricultural and farm waste through anaerobic digestion

While Turkey is one of the world's largest producers and exporters of agricultural goods, it is also, at the same time a net importer of energy carriers. This dichotomy offers a strong incentive to generate energy from agricultural and farming waste; something which could provide energy security for rural areas. Combined with the enhanced energy security for farming areas, the production of energy in this manner could conceivably contribute to the overall national effort to reduce the Turkey's carbon footprint. This study explores the environmental benefits and burdens of one such option, that is, biogas production from a mixture of agricultural and animal waste through anaerobic digestion (AD), and its subsequent use for electricity and heat generation. A life-cycle assessment methodology was used, to measure the potential environmental impact of this option, in terms of global warming and total weighed impact, and to contrast it with the impact of producing the same amount of energy via an integrated gasification combined cycle process and a hard coal power plant. This study concentrates on an AD and cogeneration pilot plant, built in the Kocaeli province of Turkey and attempts to evaluate its potential environmental impacts. The study uses laboratory-scale studies, as well as literature and LCI databases to derive the operational parameters, yield and emissions of the plant. The potential impacts were calculated with EDIP 2003 methodology, using GaBi 5 LCA software. The results indicate that N2O emissions, resulting from the application of liquid and solid portions of digestate (a by-product of AD), as an organic fertilizer, are by far the largest contributors to global warming among all the life cycle stages. They constitute 68% of the total, whereas ammonia losses from the same process are the leading cause of terrestrial eutrophication. The photochemical ozone formation potential is significantly higher for the cogeneration phase, compared to other life cycle stages of the proposed scenario, due to NOx being emitted from the gas engine during combustion. Overall, the total environmental impact of the option was determined to be ten times lower than that of a hard coal option and 50% lower than the gasification option, since the latter does not generate digestate that is able to replace mineral fertilizer, thus mitigating the environmental footprint. Finally, the sustainability of energy production from agricultural and farm waste, via AD, was further enhanced by eliminating it from conventional waste management system practiced in the region, i.e. landfilling.

Biomass and Natural Gas to Liquid Transportation Fuels and Olefins (BGTL+C2_C4): Process Synthesis and Global Optimization

This paper introduces a process synthesis and a global optimization framework toward the coproduction of liquid fuels and olefins from biomass and natural gas. A superstructure of alternatives is developed at each stage of the process with different gasification options, natural gas conversion routes, hydrocarbon production, and upgrading methods. Simultaneous heat, power, and water integration is introduced for the optimal usage of the utilities in the proposed plants. The global optimization framework with a branch-and-bound approach is utilized to determine the optimal process out of numerous alternatives that would give the maximum plant profit. The optimal topologies obtained suggest that the best possible process depends on the liquid fuels and olefins to be produced. Parametric analysis on different chemicals production levels suggests that both the profit and net present value (NPV) increases substantially at higher chemicals production levels. Economies of scale are present as the case studies at...

The potential of small-scale SNG production from biomass gasification

Synthetic natural gas (SNG) can be produced from biomass by thermochemical gasification and subsequent synthesis gas methanation and gas processing. For an industrial-scale process with high efficiency (up to 74 %; Rönsch et al. in VGB PowerTech 5:110–116, 2008), the large plant size is associated with a number of disadvantages such as a high biomass transportation volume and local environmental impacts. Small distributed SNG production units would minimize these negative aspects but are expected to cause lower efficiency. In order to show the potential of a small-scale SNG solution, different process chain configurations are simulated using Aspen Plus software. Combined heat and power generation via gasification and direct product gas conversion in a gas engine is compared to a SNG route, where the product gas is further cleaned, converted, and upgraded to SNG. Different gasification technologies (co-current fixed bed, countercurrent fixed bed, and dual fluidized bed) are evaluated. The SNG route is based on a dual fluidized bed gasification, subsequent methanation, and injection into the natural gas grid. As an outcome of the simulations, the efficiencies are calculated with special focus on heat integration and utilization. A maximized utilization of the released process heat results in a strong overall efficiency increase. Depending on the local heat utilization, gasification with subsequent methanation has an advantage compared to direct local power generation. The overall efficiency of the SNG option is found to be up to 73.9 %, which is within the range of the fluidized bed gasification option. The crucial factor for high efficiency, and thus for an economic operation, is the heat demand at the location. With even a small constant heat demand, the SNG solution becomes very competitive as some of the heat otherwise generated on-site is translated into chemical energy and carried to a power generation location elsewhere. It has been shown that SNG production subsequent of a small-scale fluidized bed gasifier can very well be efficient in both energetic and economic regards. The most important and crucial parameter is the heat utilization on-site and thus the local heat demand characteristics.

Biomass co-firing options on the emission reduction and electricity generation costs in coal-fired power plants

Co-firing offers a near-term solution for reducing CO 2 emissions from conventional fossil fuel power plants. Viable alternatives to long-term CO 2 reduction technologies such as CO 2 sequestration, oxy-firing and carbon loop combustion are being discussed, but all of them remain in the early to mid stages of development. Co-firing, on the other hand, is a well-proven technology and is in regular use though does not eliminate CO 2 emissions entirely. An incremental gain in CO 2 reduction can be achieved by immediate implementation of biomass co-firing in nearly all coal-fired power plants with minimum modifications and moderate investment, making co-firing a near-term solution for the greenhouse gas emission problem. If a majority of coal-fired boilers operating around the world adopt co-firing systems, the total reduction in CO 2 emissions would be substantial. It is the most efficient means of power generation from biomass, and it thus offers CO 2 avoidance cost lower than that for CO 2 sequestration from existing power plants. The present analysis examines several co-firing options including a novel option external (indirect) firing using combustion or gasification in an existing coal or oil fired plant. Capital and operating costs of such external units are calculated to determine the return on investment. Two of these indirect co-firing options are analyzed along with the option of direct co-firing of biomass in pulverizing mills to compare their operational merits and cost advantages with the gasification option.

Highly efficient electricity generation from biomass by integration and hybridization with combined cycle gas turbine (CCGT) plants for natural gas

Integration/co-firing with existing fossil fuel plants could give near term highly efficient and low cost power production from biomass. This paper presents a techno-economical analysis on options for integrating biomass thermal conversion (optimized for local resources 50 MW) with existing CCGT (combined cycle gas turbine) power plants (800-1400 MWth). Options include hybrid combined cycles (HCC), indirect gasification of biomass and simple cycle biomass steam plants which are simulated using the software Ebsilon Professional and Aspen Plus. Levelized cost of electricity (LCoE) is calculated with cost functions derived from power plant data. Results show that the integrated HCC configurations (fully-fired) show a significantly higher efficiency (40-41%, LHV (lower heating value)) than a stand-alone steam plant (35.5%); roughly half of the efficiency (2.4% points) is due to more efficient fuel drying. Because of higher investment costs, HCC options have cost advantages over stand-alone options at high biomass fuel prices (>25 EUR/MWh) or low discount rates (<5%). Gasification options show even higher efficiency (46-50%), and the lowest LCoE for the options studied for fuel costs exceeding 10 EUR/MWh. It can be concluded that clear efficiency improvements and possible cost reductions can be reached by integration of biomass with CCGT power plants compared to stand-alone plants.

Preliminary Economic Analysis of Poultry Litter Gasification Option with a Simple Transportation Model

Several environmental issues are related to the disposal of poultry litter. In an effort to provide a more environmentally friendly alternative than landfill disposal or spreading as a soil amendment, work has been carried out previously at the University of Tennessee Space Institute (UTSI). This past UTSI work was concentrated on developing a catalytic steam gasification concept to produce energy from poultry litter. In the past UTSI studies, preliminary design and economics for a stationary, centralized gasification plant capable of processing ∼100 ton/day of poultry litter were developed. However, in this preliminary design the economic impact of transporting litter to a centralized gasification plant location was not addressed. To determine the preliminary impact of transporting the poultry litter on the overall economics of this energy conversion plant design, a simple transportation model was developed. This model was used in conjunction with the earlier plant design prepared at UTSI to determine the economic feasibility of a centralized, stationary poultry litter gasification plant. To do so, major variables such as traveling distance, plant feed rate (or capacity), fluctuations in the sales price of the product gas (that means value of the energy), population density of poultry farms, impact of tipping fees, and cost of litter were varied. The study showed that for plant with a capacity of 1000 ton/day to be able to withstand several changes in economic conditions and sustain itself, the poultry farm density would need to be ∼0.3 houses/mi2. Smaller plants would need either a higher energy price or some kind of subsidy to be economically feasible.

Thoughts about future power generation systems and the role of exergy analysis in their development : Lior, N. Energy Conversion and Management, 2002, 43, (9–12), 1187–1198

While Turkey is one of the world's largest producers and exporters of agricultural goods, it is also, at the same time a net importer of energy carriers. This dichotomy offers a strong incentive to generate energy from agricultural and farming waste; something which could provide energy security for rural areas. Combined with the enhanced energy security for farming areas, the production of energy in this manner could conceivably contribute to the overall national effort to reduce the Turkey's carbon footprint. This study explores the environmental benefits and burdens of one such option, that is, biogas production from a mixture of agricultural and animal waste through anaerobic digestion (AD), and its subsequent use for electricity and heat generation. A life-cycle assessment methodology was used, to measure the potential environmental impact of this option, in terms of global warming and total weighed impact, and to contrast it with the impact of producing the same amount of energy via an integrated gasification combined cycle process and a hard coal power plant. This study concentrates on an AD and cogeneration pilot plant, built in the Kocaeli province of Turkey and attempts to evaluate its potential environmental impacts. The study uses laboratory-scale studies, as well as literature and LCI databases to derive the operational parameters, yield and emissions of the plant. The potential impacts were calculated with EDIP 2003 methodology, using GaBi 5 LCA software. The results indicate that N2O emissions, resulting from the application of liquid and solid portions of digestate (a by-product of AD), as an organic fertilizer, are by far the largest contributors to global warming among all the life cycle stages. They constitute 68% of the total, whereas ammonia losses from the same process are the leading cause of terrestrial eutrophication. The photochemical ozone formation potential is significantly higher for the cogeneration phase, compared to other life cycle stages of the proposed scenario, due to NOx being emitted from the gas engine during combustion. Overall, the total environmental impact of the option was determined to be ten times lower than that of a hard coal option and 50% lower than the gasification option, since the latter does not generate digestate that is able to replace mineral fertilizer, thus mitigating the environmental footprint. Finally, the sustainability of energy production from agricultural and farm waste, via AD, was further enhanced by eliminating it from conventional waste management system practiced in the region, i.e. landfilling.

Coal gasification in a deintegrated electricity industry

This paper examines coal gasification in the context of a regulated utility purchasing power from an independent power producer (IPP). It outlines various contractual approaches that might be used to achieve coordination between the profit motive of the IPP and the desirability of limiting the potential escalation of natural gas prices through a backstop technology. These approaches are formulated as options. A numerical method to value the gasification option is presented. The option value is found to be significant (although uncertain). The transactions costs associated with writing contracts to incorporate the option value are substantial. Vertical integration may handle these issues more easily.

The energy contribution potential for medium-Btu gas produced from biomass in the USA

This paper presents a preliminary assessment of the potential market for medium-Btu fuel gas from biomass. It discusses the market niche, current market potential and future market based on an analysis of published information. Several conclusions are drawn, based on this analysis. Both biomass and coal medium-Btu gasification technologies share the same market niche for gasifiers with thermal capacities ranging between 15 and 200 MW. The analysis also indicates that medium-Btu gasification technology has potential advantages over low-Btu gasification options using biomass or coal in many applications where both technologies compete. It was also found that a current market of up to 4·7×10 15 kJ annually exists for medium-Btu fuel gas plants in this size range. Further, up to one third of this potential market exists in states where coal is not expected to be a competitive alternative fuel. Finally, a future market potential for medium-Btu gas from biomass exists in cogeneration applications.