| 1. |
- Ahlström, Johan, 1990, et al.
(författare)
-
Bark as feedstock for dual fluidized bed gasifiers. Operability, efficiency, and economics
- 2019
-
Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 43:3, s. 1171-1190
-
Tidskriftsartikel (refereegranskat)abstract
- The demand for biofuels and biochemicals is expected to increase in the future, which will in turn increase the demand for biomass feedstock. Large gasification plants fueled with biomass feedstock are likely to be a key enabling technology in a resource-efficient, bio-based economy. Furthermore, the costs for producing biofuels and biochemicals in such plants could potentially be decreased by utilizing inexpensive low-grade residual biomass as feedstock. This study investigates the usage of shredded tree bark as a feedstock for the production of biomethane in the GoBiGas demonstration plant in Gothenburg, Sweden, based on a 32 MWth industrial dual fluidized bed gasification unit. The plant was operated with bark feedstock for 12 000 hours during the period 2014 to 2018. Data from the measurement campaign were processed using a stochastic approach to establish the plant's mass and energy balances, which were then compared with operation of the plant with wood pellets. For this comparison, an extrapolation algorithm was developed to predict plant performance using bark dried to the same moisture content as wood pellets, ie, 8%w.b. Plant operation with bark feedstock was evaluated for operability, efficiency, and feedstock-related cost. The gas quality achieved during the test period was similar to that obtained for operation with wood pellets. Furthermore, no significant ash sintering or agglomeration problems were observed more than 750 hours of operation. The calculated biomass-to-biomethane efficiency is 43% to 47% (lower heating value basis) for operation with wet bark. However, the predicted biomass-to-biomethane efficiency can be increased to 55%–65% for operation with bark feedstock dried to 8% moisture content, with corresponding feedstock costs in the range of 24.2 to 32.7 EUR/MWh; ie, a cost reduction of about 40% compared with wood pellets.
|
|
| 2. |
- Alamia, Alberto, 1984, et al.
(författare)
-
Efficiency Comparison of Large-Scale Standalone, Centralized, and Distributed Thermochemical Biorefineries
- 2017
-
Ingår i: Energy Technology. - : Wiley. - 2194-4296 .- 2194-4288. ; 5:8, s. 1435-1448
-
Tidskriftsartikel (refereegranskat)abstract
- © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.We present a comparison of three strategies for the introduction of new biorefineries: standalone and centralized drop-in, which are placed within a cluster of chemical industries, and distributed drop-in, which is connected to other plants by a pipeline. The aim was to quantify the efficiencies and the production ranges to support local transition to a circular economy based on biomass usage. The products considered are biomethane (standalone) and hydrogen/biomethane and sustainable town gas (centralized drop-in and distributed drop-in). The analysis is based on a flow-sheet simulation of different process designs at the 100MWbiomass scale and includes the following aspects: advanced drying systems, the coproduction of ethanol, and power-to-gas conversion by direct heating or water electrolysis. For the standalone plant, the chemical efficiency was in the range of 78-82.8% LHVa.r.50% (lower heating value of the as-received biomass with 50% wet basis moisture), with a maximum production of 72MWCH4 , and for the centralized drop-in and distributed drop-in plants, the chemical efficiency was in the range of 82.8-98.5% LHVa.r.50% with maximum production levels of 85.6MWSTG and 22.5MWH2 /51MWCH4 , respectively. It is concluded that standalone plants offer no substantial advantages over distributed drop-in or centralized drop-in plants unless methane is the desired product.
|
|
| 3. |
- Alamia, Alberto, 1984, et al.
(författare)
-
Performance of large-scale biomass gasifiers in a biorefinery, a state-of-the-art reference
- 2017
-
Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 41:14, s. 2001-2019
-
Tidskriftsartikel (refereegranskat)abstract
- The Gothenburg Biomass Gasification plant (2015) is currently the largest plant in the world producing biomethane (20 MWbiomethane) from woody biomass. We present the experimental data from the first measurement campaign and evaluate the mass and energy balances of the gasification sections at the plant. Measures improving the efficiency including the use of additives (potassium and sulfur), high-temperature pre-heating of the inlet streams, improved insulation of the reactors, drying of the biomass and introduction of electricity as a heat source (power-to-gas) are investigated with simulations. The cold gas efficiency was calculated in 71.7%LHVdaf using dried biomass (8% moist). The gasifier reaches high fuel conversion, with char gasification of 54%, and the fraction of the volatiles is converted to methane of 34%mass. Because of the design, the heat losses are significant (5.2%LHVdaf), which affect the efficiency. The combination of potential improvements can increase the cold gas efficiency to 83.5%LHVdaf, which is technically feasible in a commercial plant. The experience gained from the Gothenburg Biomass Gasification plant reveals the strong potential biomass gasification at large scale.
|
|
| 4. |
- Alamia, Alberto, 1984, et al.
(författare)
-
Assessment of waste heat recovery for a power generation system based on Volvo dual fuel engines
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The electricity production from distributed renewable energy sources, like wind or solar PV, has considerably increased in last decade. To ensure a wide penetration of these renewable sources is necessary to integrate the fluctuation in the electricity production within the existing power network, even in network with limited transfer capacity between clusters.This work investigates possibilities to integrate the fluctuations of the renewable energy sources with production of electricity with a system based on internal combustion engines of the Dual Fuel (DF) type using synthetic natural gas (SNG), and waste heat recovery (WHR).The system retains high flexibility in the electricity output (i.e. quick regulation), and high efficiency comparable to large electricity plants.The design is based on a set of four medium size DF engines for a total power of around 2MW, and a WHR cycle operated with steam. The results showed an efficiency above 50% in a large range of operation of the engines with a peak above 52%, therefore comparable to gas turbine plants. Two designs of the WHR system were investigated (high pressure and low pressure) to improve heat recovery. The high pressure configuration is considered more suitable due to the lower complexity (single heat exchanger), which can be further exploited to expand the number of engines.The efficiency of the steam turbine/expander is the most critical parameter for the WHR system. However, the results showed that even with low efficiency of steam turbine (ηST 50% - 60%) the total efficiency can reach above 50%, when the engines are operated at high load. A high efficiency steam turbine (ηST 80% - 90%) can rise the total efficiency by 2.5 percentile units.
|
|
| 5. |
- Alamia, Alberto, 1984, et al.
(författare)
-
Design of an integrated dryer and conveyor belt for woody biofuels
- 2015
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 77, s. 92-109
-
Tidskriftsartikel (refereegranskat)abstract
- Combustion or gasification of high-moisture content biomass is associated with a number of drawbacks, such as operational instabilities and lowered total efficiency. The present work proposes an integrated dryer and conveyor belt for woody biofuels with steam as the heat transfer medium. The use of low-temperature steam is favorable from a heat management point of view, but also helps to minimize the risk of fire, self-ignition and dust explosions. Furthermore, the presented dryer design represents an efficient combination of fuel transport, drying equipment and fuel feeding system.The proposed design is developed from a macroscopic energy and mass balance model that uses results from computational fluid dynamics (CFD) fuel bed modeling and experiments as its input. This CFD simulation setup can be further used to optimize the design with respect to bed height, steam injection temperatures and fuel type. The macroscopic model can be used to investigate the integration of the dryer within a larger biomass plant. Such a case study is also presented, where the dryer is tailored for integration within an indirect steam gasification system. It is found that the exergy efficiency of this dryer is 52.9%, which is considerably higher than those of other dryers using air or steam, making the proposed drying technology a very competitive choice for operation with indirect steam gasification units.
|
|
| 6. |
- Alamia, Alberto, 1984, et al.
(författare)
-
Fuel Quality Analysis for Biogas Utilization in Heavy Duty Dual Fuel Engines
- 2012
-
Ingår i: World BioEnergy 2012 - conference in Jönköping , May 2012. ; , s. 1-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The perspective of using gas form biomass gasification as fuel for dual fuel (DF) engines, without refine it all the way to synthetic natural gas (SNG) has been investigated. The initial gas from gasification contains of a blend of various components which are not commonly present in natural gas (NG). The operability of these components in a heavy duty DF engine has been assessed and compared to those of NG. Three parameters have been used to define the quality of the fuel: Lower Heating Value (LHV), Methane Number (MN) and Lower Flammability Limit (LFL).
|
|
| 7. |
- Alamia, Alberto, 1984, et al.
(författare)
-
Fuel Quality Analysis for Biogas Utilization in Heavy Duty Dual Fuel Engines
- 2012
-
Ingår i: 20th European Biomass conference & exhibition - Milan -June 2012. - 9788889407547 ; , s. 5-
-
Konferensbidrag (refereegranskat)abstract
- Internal combustion engines using oil-derived fuels are dominating the heavy transportation sector today. However, the climate issue and security of supply drive the development towards new fuels and engine technologies. In the short term, Natural Gas (NG) is expected to have a dominant role, due to its high availability and a favourable H/C ratio. Thereafter, it is expect an introduction of biofuels of second and third generations. In this scenario the engine suppliers need to develop engines for various fuels of both fossil and renewable origin. One possibility is the Dual Fuel engine (DF), which uses a Diesel pilot to ignite a gas mixture and, it can be used for natural gas of various qualities as well as synthetic natural gas (SNG). To obtain significant share of second and third generation biofuels into the transportation sector a key process is gasification of the raw solid biomass to gas, as it can offer high production capacity and high efficiency. One interesting biofuel is SNG and at present there are a number of projects focusing on SNG production through gasification of biomass to be fed to the NG grid. However, this is a rather advanced and several stage process. The initial gas from the gasification before the gas is upgraded to CH4 (SNG) contains of a blend of various gas components such as H2, CO, CO2, CH4 and fractions of C2H2, C2H4, C3H6, and C3H8, as well as, longer hydrocarbons. The upgrading takes place in many process steps, where each step involves a cost and loss of energy. The question raised is if there are more efficient routs to introduce biomass derived gas than refine it all the way to SNG, from a well to wheel (WTW) perspective? The first step in such an analysis is to investigate how different gas mixtures could meet emission limits, together with the required performance of efficiency and load. This issue has been addressed in this work, where the operability in DF engines using gaseous fuels with a variation in fuel quality has been investigated. The operability has a key role in the optimization of the WTW efficiency, since it influences both the production process and the combustion in the engine. The definition of fuel quality for gaseous fuels to be used in gas engines is still not in place and proper legislation and standards are not available. Here, three parameters which are fundamental for a proper combustion in a DF engine: the Methane Number (MN), the Lower Flammability Limit (LFL) and the Lower Heating Value (LHV) have been studied. All parameters influence the combustion performance in the DF engine of the Port-injected type, which is more sensitive to the fuel quality than the Direct-injected type. The components available from biomass gasification were evaluated together with those from different NG compositions on the European market. Specific relations between the composition and fuel quality parameters have been derived, which can be used as starting point for future well to wheel analysis.
|
|
| 8. |
- Alamia, Alberto, 1984, et al.
(författare)
-
Hydrogen from Biomass Gasification for Utilization in Oil Refineries
- 2012
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- If taxes fees and other restriction on fossil fuels are not considered the cost for the fuels produced from biomass gasification will still be higher than that of oil-based fuels or natural gas for next decades.Nevertheless, there is room for other application of the biomass gasification followed by gas upgrading rather than fuel production. The proposed idea is a gasification-upgrading process optimized for hydrogen production, intended for the integration in an oil refinery. Driving forces for the introduction of this process are; 1, thedependency of the crude oil price on the sulfur content, 2, making use of low temperature waste heat and 3, the possibility to utilize existing infrastructure to introduce renewable energy sources (RES) in the refinery.The hydrodesulfurization of the refined petroleum productsrequires pure hydrogen, which is usually obtained from the one contained in the oil itself. Crude oils with unfavorable sulfur to hydrogen ratio have a lower price on the market, but they require extra hydrogen for the desulfurization process. Hence, there is roomfor introducing an extra source of hydrogen from a RES as biomass. Despite the technological challenge introduction of a new process causes, a high marginal profit can be achieved from the purchase of low price crude oil with high sulfur content.The process proposed in this work is suitable for integration, since it requires mainly low temperature heat (150 °C) which is abundant in an oil refinery and a small amount of electricity. The gasification process could then be seen as a perfect heat sink for low temperature waste heat, which otherwise usually is lost due to heatexchanging with the surrounding air.
|
|
| 9. |
- Alamia, Alberto, 1984
(författare)
-
Indirect gasification production of biomethane for use in heavy-duty state-of-the-art gas engines
- 2015
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The climate targets set for the European transport sector have stimulated intensiveresearch by groups in academia, the energy industry, and vehicle manufacturing in theGothenburg region into biomethane production via indirect gasification of lignocellulosebiomass and the development of advanced gas engine technologies.This work presents the results of a comprehensive study of biomethane production andutilization in heavy duty engines. The different steps in the biomethane chain (biomassdrying, gasification process, and combustion) are assessed, and opportunities forimproving the efficiency of utilization of biomass resources are evaluated. The biomethanechain is investigated through a well-to-wheel (WtW) analysis of the newly built GoBiGasplant (Gothenburg, Sweden), in combination with three state-of-the-art gas enginestechnologies: spark-ignited (SI); dual fuel (DF); and high-pressure direct injection (HPDI).Opportunities for improving the biomethane process are focused on the drying system andon the dual fluidized bed gasifier. An advanced drying system for the dual fluidized bedgasifier, which uses low-temperature steam as the drying medium and recovers theevaporated moisture as a gasification agent, is evaluated. A method for simulating theprocess that occurs in the dual fluidized bed gasifier using experimental data is introduced,with the aim of exploiting the extensive body of information derived from pilot anddemonstration gasifiers in relation to process optimization and techno-economic analyses.The uncertainty that arises from the measurements is assessed stochastically andtransferred to process parameters.The WtW analysis shows that emissions from biomethane are reduced by 73%, 46%, and68% when used in the SI, DF, and HPDI engines, respectively, as compared to using NG andLNG. The evaluation of the drying process reveals a theoretical energy efficiency of 95%when combined with a DFB gasifier and an exergy efficiency of 53%, values that areconsiderably higher than those obtained with other drying systems. Through interpolationiiand extrapolation of the experimental data, the proposed modeling method isdemonstrated to be a flexible tool for simulating the gasifier under several operationalconditions Comparisons of the data from different measurement set-ups demonstrate thata detection rate of ≥95% for the carbon in the produced gas is necessary to keep theuncertainty at
|
|
| 10. |
- Alamia, Alberto, 1984
(författare)
-
Large-Scale Production and Use of Biomethane
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Societal ambitions to create an economy based on renewable resources, require the development of technologies transforming these resources into energy-carrying products and biomaterials. Dual fluidized bed (DFB) gasification represents a key technology for achieving sustainability targets, as it is a scalable and highly efficient route for the conversion of biomass. The development of DFB technology has led to the construction of the GoBiGas (Gothenburg-Biomass-Gasification) demonstration plant, in 2014. The GoBiGas plant is a world-first advancement for large-scale production of biofuels as it represents a substantial scaling up of the gasification technology combined with downstream biomethane synthesis. However, to ensure the desired breakthrough of biomass-based products, it is necessary to improve the profitability of gasification plants, through increasing their size, efficiency and identifying opportunities with high economic feasibility for the transport, energy, and chemical sectors.This thesis presents an exploration of potential improvements for the up-scaling of the biomethane process to a commercial scale. The work summarises and places in context the experience acquired in the research groups at Chalmers and Göteborg Energi AB, including the experience gained from the dedicated experiments in the Chalmers Gasifier and during the commissioning phase of the GoBiGas plant. A method for analysis of the experimental data is introduced, with the goal of improving the quality of the simulations of large-scale gasification processes. The method is applied to the evaluation of the DFB gasifier at the GoBiGas plant, which is presented in the thesis and used as references for further investigations. Some of the measures investigated to increase the profitability of a large-scale plant were proposed in this work, including: an advanced biomass steam dryer integrated with the gasifier, power-to-gas conversion via direct heating of the DFB gasifier and co-production of biomethane with intermediate products for other chemical industries. Furthermore, the utilization of biomethane as fuel for heavy duty vehicles was evaluated within a project in collaboration with Volvo AB. The well-to-wheel approach was applied to calculate the emissions related to three state-of-the-technologies: spark-ignited, dual fuel and high-pressure direct injection.The evaluation of the DFB gasifier at GoBiGas has shown high fuel conversion, with char gasification of ~54%, and the fraction of the volatiles converted to methane of ~34%mass. The cold gas efficiency for GoBiGas was calculate in 71.7%LHVdaf using dried biomass (8% moist). The simulation of the DFB gasifier in a large-scale optimised process showed a cold gas efficiency up to ~85%LHVdaf using fresh biomass (40% moist) and an advanced drying systems. The chemical efficiency of such a plant was calculated in ~72% LHVdaf, which is more than 20pp higher than the current GoBiGas design. Owning to the efficient conversion of the biomass in the gasifier, the co-production of biomethane and other intermediate chemicals represents a feasible opportunity to increase the profitability of the plant. The chemical efficiency of such processes was estimated between 72% and 85% therefore, there is no substantial advantage to produce biomethane, unless biomethane is the desired end-product. As fuel for heavy-duty vehicles, biomethane reduces the emissions compared to diesel by 30 - 41 gCO2e per MJbiomass, with the biomethane produced at the GoBiGas plant. The emission saving can be increased to 43 - 54 gCO2esaved/MJbiomass if biomethane is produced at large scale. Following the demonstration at a commercial scale, biomethane is established as a biofuel with a high environmental impact, although the gap between the current status and its potential application is highlighted.
|
|
