| 1. |
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| 2. |
- Ahmadi, Mozhgan, et al.
(författare)
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Development of an on-line tar measurement method based on photo ionization technique
- 2011
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 176:1, s. 250-252
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents work in progress for development of an on-line method based on PID (Photo Ionization Detector) for quantitative measurement of tar from biomass gasification. To calibrate the method the PID signals are compared to quantitative data of individual tar compounds obtained by an established reference method. The measured response factors for the model tar compounds demonstrated very good linearity. The PID approach was tested on-line with real producer gases from an atmospheric fluidized bed gasifier operated at 800-900 °C. The results suggest that PID can be used for continuous on-line tar measurement of product gases from biomass gasification.
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| 3. |
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| 4. |
- Alvfors, Per, 1954-, et al.
(författare)
-
Research and development challenges for Swedish biofuel actors – three illustrative examples : Improvement potential discussed in the context of Well-to-Tank analyses
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Currently biofuels have strong political support, both in the EU and Sweden. The EU has, for example, set a target for the use of renewable fuels in the transportation sector stating that all EU member states should use 10% renewable fuels for transport by 2020. Fulfilling this ambition will lead to an enormous market for biofuels during the coming decade. To avoid increasing production of biofuels based on agriculture crops that require considerable use of arable area, focus is now to move towards more advanced second generation (2G) biofuels that can be produced from biomass feedstocks associated with a more efficient land use. Climate benefits and greenhouse gas (GHG) balances are aspects often discussed in conjunction with sustainability and biofuels. The total GHG emissions associated with production and usage of biofuels depend on the entire fuel production chain, mainly the agriculture or forestry feedstock systems and the manufacturing process. To compare different biofuel production pathways it is essential to conduct an environmental assessment using the well-to-tank (WTT) analysis methodology. In Sweden the conditions for biomass production are favourable and we have promising second generation biofuels technologies that are currently in the demonstration phase. In this study we have chosen to focus on cellulose based ethanol, methane from gasification of solid wood as well as DME from gasification of black liquor, with the purpose of identifying research and development potentials that may result in improvements in the WTT emission values. The main objective of this study is thus to identify research and development challenges for Swedish biofuel actors based on literature studies as well as discussions with the the researchers themselves. We have also discussed improvement potentials for the agriculture and forestry part of the WTT chain. The aim of this study is to, in the context of WTT analyses, (i) increase knowledge about the complexity of biofuel production, (ii) identify and discuss improvement potentials, regarding energy efficiency and GHG emissions, for three biofuel production cases, as well as (iii) identify and discuss improvement potentials regarding biomass supply, including agriculture/forestry. The scope of the study is limited to discussing the technologies, system aspects and climate impacts associated with the production stage. Aspects such as the influence on biodiversity and other environmental and social parameters fall beyond the scope of this study. We find that improvement potentials for emissions reductions within the agriculture/forestry part of the WTT chain include changing the use of diesel to low-CO2-emitting fuels, changing to more fuel-efficient tractors, more efficient cultivation and manufacture of fertilizers (commercial nitrogen fertilizer can be produced in plants which have nitrous oxide gas cleaning) as well as improved fertilization strategies (more precise nitrogen application during the cropping season). Furthermore, the cultivation of annual feedstock crops could be avoided on land rich in carbon, such as peat soils and new agriculture systems could be introduced that lower the demand for ploughing and harrowing. Other options for improving the WTT emission values includes introducing new types of crops, such as wheat with higher content of starch or willow with a higher content of cellulose. From the case study on lignocellulosic ethanol we find that 2G ethanol, with co-production of biogas, electricity, heat and/or wood pellet, has a promising role to play in the development of sustainable biofuel production systems. Depending on available raw materials, heat sinks, demand for biogas as vehicle fuel and existing 1G ethanol plants suitable for integration, 2G ethanol production systems may be designed differently to optimize the economic conditions and maximize profitability. However, the complexity connected to the development of the most optimal production systems require improved knowledge and involvement of several actors from different competence areas, such as chemical and biochemical engineering, process design and integration and energy and environmental systems analysis, which may be a potential barrier.
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| 5. |
- Alvfors, Per, et al.
(författare)
-
Research and development challenges for Swedish biofuel actors – three illustrative examples
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Currently biofuels have strong political support, both in the EU and Sweden. The EU has, for example, set a target for the use of renewable fuels in the transportation sector stating that all EU member states should use 10% renewable fuels for transport by 2020. Fulfilling this ambition will lead to an enormous market for biofuels during the coming decade. To avoid increasing production of biofuels based on agriculture crops that require considerable use of arable area, focus is now to move towards more advanced second generation (2G) biofuels that can be produced from biomass feedstocks associated with a more efficient land use.Climate benefits and greenhouse gas (GHG) balances are aspects often discussed in conjunction with sustainability and biofuels. The total GHG emissions associated with production and usage of biofuels depend on the entire fuel production chain, mainly the agriculture or forestry feedstock systems and the manufacturing process. To compare different biofuel production pathways it is essential to conduct an environmental assessment using the well-to-tank (WTT) analysis methodology. In Sweden the conditions for biomass production are favourable and we have promising second generation biofuels technologies that are currently in the demonstration phase. In this study we have chosen to focus on cellulose based ethanol, methane from gasification of solid wood as well as DME from gasification of black liquor, with the purpose of identifying research and development potentials that may result in improvements in the WTT emission values. The main objective of this study is thus to identify research and development challenges for Swedish biofuel actors based on literature studies as well as discussions with the the researchers themselves. We have also discussed improvement potentials for the agriculture and forestry part of the WTT chain. The aim of this study is to, in the context of WTT analyses, (i) increase knowledge about the complexity of biofuel production, (ii) identify and discuss improvement potentials, regarding energy efficiency and GHG emissions, for three biofuel production cases, as well as (iii) identify and discuss improvement potentials regarding biomass supply, including agriculture/forestry. The scope of the study is limited to discussing the technologies, system aspects and climate impacts associated with the production stage. Aspects such as the influence on biodiversity and other environmental and social parameters fall beyond the scope of this study. We find that improvement potentials for emissions reductions within the agriculture/forestry part of the WTT chain include changing the use of diesel to low-CO2-emitting fuels, changing to more fuel-efficient tractors, more efficient cultivation and manufacture of fertilizers (commercial nitrogen fertilizer can be produced in plants which have nitrous oxide gas cleaning) as well as improved fertilization strategies (more precise nitrogen application during the cropping season). Furthermore, the cultivation of annual feedstock crops could be avoided on land rich in carbon, such as peat soils and new agriculture systems could be introduced that lower the demand for ploughing and harrowing. Other options for improving the WTT emission values includes introducing new types of crops, such as wheat with higher content of starch or willow with a higher content of cellulose. From the case study on lignocellulosic ethanol we find that 2G ethanol, with co-production of biogas, electricity, heat and/or wood pellet, has a promising role to play in the development of sustainable biofuel production systems. Depending on available raw materials, heat sinks, demand for biogas as vehicle fuel and existing 1G ethanol plants suitable for integration, 2G ethanol production systems may be designed differently to optimize the economic conditions and maximize profitability. However, the complexity connected to the development of the most optimal production systems require improved knowledge and involvement of several actors from different competence areas, such as chemical and biochemical engineering, process design and integration and energy and environmental systems analysis, which may be a potential barrier. Three important results from the lignocellulosic ethanol study are: (i) the production systems could be far more complex and intelligently designed than previous studies show, (ii) the potential improvements consist of a large number of combinations of process integration options wich partly depends on specific local conditions, (iii) the environmental performance of individual systems may vary significantly due to systems design and local conditons.From the case study on gasification of solid biomass for the production of biomethane we find that one of the main advantages of this technology is its high efficiency in respect to converting biomass into fuels for transport. For future research we see a need for improvements within the gas up-grading section, including gas cleaning and gas conditioning, to obtain a more efficient process. A major challenge is to remove the tar before the methanation reaction. Three important results from the biomethane study are: (i) it is important not to crack the methane already produced in the syngas, which indicates a need for improved catalysts for selective tar cracking, (ii) there is a need for new gas separation techniques to facilitate the use of air oxidation agent instead of oxygen in the gasifier, and (iii) there is a need for testing the integrated process under realistic conditions, both at atmospheric and pressurized conditions. From the case study on black liquor gasification for the production of DME we find that the process has many advantages compared to other biofuel production options, such as the fact that black liquor is already partially processed and exists in a pumpable, liquid form, and that the process is pressurised and tightly integrated with the pulp mill, which enhances fuel production efficiency. However, to achieve commercial status, some challenges still remain, such as demonstrating that materials and plant equipment meet the high availability required when scaling up to industrial size in the pulp mill, and also proving that the plant can operate according to calculated heat and material balances. Three important results from the DME study are: (i) that modern chemical pulp mills, having a potential surplus of energy, could become important suppliers of renewable fuels for transport, (ii) there is a need to demonstrate that renewable DME/methanol will be proven to function in large scale, and (iii) there is still potential for technology improvements and enhanced energy integration. Although quantitative improvement potentials are given in the three biofuel production cases, it is not obvious how these potentials would affect WTT values, since the biofuel production processes are complex and changing one parameter impacts other parameters. The improvement potentials are therefore discussed qualitatively. From the entire study we have come to agree on the following common conclusions: (i) research and development in Sweden within the three studied 2G biofuel production technologies is extensive, (ii) in general, the processes, within the three cases, work well at pilot and demonstration scale and are now in a phase to be proven in large scale, (iii) there is still room for improvement although some processes have been known for decades, (iv) the biofuel production processes are complex and site specific and process improvements need to be seen and judged from a broad systems perspective (both within the production plant as well as in the entire well-to-tank perspective), and (v) the three studied biofuel production systems are complementary technologies. Futher, the process of conducting this study is worth mentioning as a result itself, i.e. that many different actors within the field have proven their ability and willingness to contribute to a common report, and that the cooperation climate was very positive and bodes well for possible future collaboration within the framework of the f3 center. Finally, judging from the political ambitions it is clear that the demand for renewable fuels will significantly increase during the coming decade. This will most likely result in opportunities for a range of biofuel options. The studied biofuel options all represent 2G biofuels and they can all be part of the solution to meet the increased renewable fuel demand.
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| 6. |
- Alvors, Per, et al.
(författare)
-
Research and development challenges for Swedish biofuel actors – three illustrative examples : Improvement potential discussed in the context of Well-to-Tank analyses
- 2010
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Currently biofuels have strong political support, both in the EU and Sweden. The EU has, for example, set a target for the use of renewable fuels in the transportation sector stating that all EU member states should use 10% renewable fuels for transport by 2020. Fulfilling this ambition will lead to an enormous market for biofuels during the coming decade. To avoid increasing production of biofuels based on agriculture crops that require considerable use of arable area, focus is now to move towards more advanced second generation (2G) biofuels that can be produced from biomass feedstocks associated with a more efficient land use.Climate benefits and greenhouse gas (GHG) balances are aspects often discussed in conjunction with sustainability and biofuels. The total GHG emissions associated with production and usage of biofuels depend on the entire fuel production chain, mainly the agriculture or forestry feedstock systems and the manufacturing process. To compare different biofuel production pathways it is essential to conduct an environmental assessment using the well-to-tank (WTT) analysis methodology.In Sweden the conditions for biomass production are favourable and we have promising second generation biofuels technologies that are currently in the demonstration phase. In this study we have chosen to focus on cellulose based ethanol, methane from gasification of solid wood as well as DME from gasification of black liquor, with the purpose of identifying research and development potentials that may result in improvements in the WTT emission values. The main objective of this study is thus to identify research and development challenges for Swedish biofuel actors based on literature studies as well as discussions with the the researchers themselves. We have also discussed improvement potentials for the agriculture and forestry part of the WTT chain. The aim of this study is to, in the context of WTT analyses, (i) increase knowledge about the complexity of biofuel production, (ii) identify and discuss improvement potentials, regarding energy efficiency and GHG emissions, for three biofuel production cases, as well as (iii) identify and discuss improvement potentials regarding biomass supply, including agriculture/forestry. The scope of the study is limited to discussing the technologies, system aspects and climate impacts associated with the production stage. Aspects such as the influence on biodiversity and other environmental and social parameters fall beyond the scope of this study.We find that improvement potentials for emissions reductions within the agriculture/forestry part of the WTT chain include changing the use of diesel to low-CO2-emitting fuels, changing to more fuel-efficient tractors, more efficient cultivation and manufacture of fertilizers (commercial nitrogen fertilizer can be produced in plants which have nitrous oxide gas cleaning) as well as improved fertilization strategies (more precise nitrogen application during the cropping season). Furthermore, the cultivation of annual feedstock crops could be avoided on land rich in carbon, such as peat soils and new agriculture systems could be introduced that lower the demand for ploughing and harrowing. Other options for improving the WTT emission values includes introducing new types of crops, such as wheat with higher content of starch or willow with a higher content of cellulose.From the case study on lignocellulosic ethanol we find that 2G ethanol, with co-production of biogas, electricity, heat and/or wood pellet, has a promising role to play in the development of sustainable biofuel production systems. Depending on available raw materials, heat sinks, demand for biogas as vehicle fuel and existing 1G ethanol plants suitable for integration, 2G ethanol production systems may be designed differently to optimize the economic conditions and maximize profitability. However, the complexity connected to the development of the most optimal production systems require improved knowledge and involvement of several actors from different competence areas, such as chemical and biochemical engineering, process design and integration and energy and environmental systems analysis, which may be a potential barrier.Three important results from the lignocellulosic ethanol study are: (i) the production systems could be far more complex and intelligently designed than previous studies show, (ii) the potential improvements consist of a large number of combinations of process integration options wich partly depends on specific local conditions, (iii) the environmental performance of individual systems may vary significantly due to systems design and local conditons.From the case study on gasification of solid biomass for the production of biomethane we find that one of the main advantages of this technology is its high efficiency in respect to converting biomass into fuels for transport. For future research we see a need for improvements within the gas up-grading section, including gas cleaning and gas conditioning, to obtain a more efficient process. A major challenge is to remove the tar before the methanation reaction.Three important results from the biomethane study are: (i) it is important not to crack the methane already produced in the syngas, which indicates a need for improved catalysts for selective tar cracking, (ii) there is a need for new gas separation techniques to facilitate the use of air oxidation agent instead of oxygen in the gasifier, and (iii) there is a need for testing the integrated process under realistic conditions, both at atmospheric and pressurized conditions.From the case study on black liquor gasification for the production of DME we find that the process has many advantages compared to other biofuel production options, such as the fact that black liquor is already partially processed and exists in a pumpable, liquid form, and that the process is pressurised and tightly integrated with the pulp mill, which enhances fuel production efficiency. However, to achieve commercial status, some challenges still remain, such as demonstrating that materials and plant equipment meet the high availability required when scaling up to industrial size in the pulp mill, and also proving that the plant can operate according to calculated heat and material balances. Three important results from the DME study are: (i) that modern chemical pulp mills, having a potential surplus of energy, could become important suppliers of renewable fuels for transport, (ii) there is a need to demonstrate that renewable DME/methanol will be proven to function in large scale, and (iii) there is still potential for technology improvements and enhanced energy integration.Although quantitative improvement potentials are given in the three biofuel production cases, it is not obvious how these potentials would affect WTT values, since the biofuel production processes are complex and changing one parameter impacts other parameters. The improvement potentials are therefore discussed qualitatively. From the entire study we have come to agree on the following common conclusions: (i) research and development in Sweden within the three studied 2G biofuel production technologies is extensive, (ii) in general, the processes, within the three cases, work well at pilot and demonstration scale and are now in a phase to be proven in large scale, (iii) there is still room for improvement although some processes have been known for decades, (iv) the biofuel production processes are complex and site specific and process improvements need to be seen and judged from a broad systems perspective (both within the production plant as well as in the entire well-to-tank perspective), and (v) the three studied biofuel production systems are complementary technologies. Futher, the process of conducting this study is worth mentioning as a result itself, i.e. that many different actors within the field have proven their ability and willingness to contribute to a common report, and that the cooperation climate was very positive and bodes well for possible future collaboration within the framework of the f3 center.Finally, judging from the political ambitions it is clear that the demand for renewable fuels will significantly increase during the coming decade. This will most likely result in opportunities for a range of biofuel options. The studied biofuel options all represent 2G biofuels and they can all be part of the solution to meet the increased renewable fuel demand.
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| 7. |
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| 8. |
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| 9. |
- Bellais, Michel, 1971-
(författare)
-
Modelling of the pyrolysis of large wood particles
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood is an interesting alternative to fossil fuels. It is CO2-neutral and widely available. However it is a difficult fuel to handle which features a low energy content. Thus technologies for wood thermal conversion need to be improved. This work concerns the development of a comprehensive two-dimensional mathematical model describing the pyrolysis of large wood particles and its implementation in a Fortran program. The model has been continuously tested and improved by experimental results obtained in a reactor for single particle pyrolysis (SPAR) at the Division of Physical Chemistry at Göteborg University. The first part of the thesis (Paper I) presents a kinetic study of the pyrolysis of large wood particles, based on experiments carried out in the SPAR. Three pyrolysis kinetic schemes were selected for later inclusion in a model featuring heat and mass transfer. Paper II concerns the addition of a sub-model for heat and mass transfer to the three kinetic schemes. The resulting model for large wood particles has been tested against experiments in the SPAR. A scheme based on two competing reactions developed from experiments at low temperature pyrolysis in the SPAR was found to perform well but its empirical nature limits its validity to the experimental conditions of the SPAR. A scheme from the literature based on TGA experiments appeared promising, especially when planning to enhance it with secondary reactions. Paper III deals with the development of shrinkage models for 2D cylindrical particles. The predicted mass loss, size variation and surface temperature were tested against experiments carried out in the SPAR. The shrinkage does not a?ect the pyrolysis rate or the surface temperature in the conditions prevailing in the SPAR. Paper IV investigates the influence of different shrinkage models and the geometry on the heating rate of a shrinking particle. Shrinkage influences the heating rate positively by increasing the conductive heat flow and negatively by decreasing the surface area of the particle. Therefore the net effect of shrinkage on the heating rate depends on the particle geometry and the location of shrinkage. Paper V studies three di?erent models for wood drying under pyrolysis conditions. The predicted surface temperature and global drying rate were compared with experimental results from pyrolysis experiments of wet particles in the SPAR. A model based on a first order kinetic evaporation rate was found to be the most interesting because of the quality of the prediction of the drying rate and the ease of implementation.
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| 10. |
- Bellais, Michel, et al.
(författare)
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Pyrolysis of large wood particles : a study of shrinkage importance in simulations
- 2003
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Ingår i: Fuel. - 0016-2361 .- 1873-7153. ; 82:12, s. 1541-1548
-
Tidskriftsartikel (refereegranskat)abstract
- Shrinkage models have been developed and included in a model for the pyrolysis of large wood particles. Shrinkage is modelled in three different ways: uniform shrinkage, shrinking shell and shrinking cylinders. These models and a reference model without shrinkage are compared with experimental data for mass loss versus time during pyrolysis of birch cylinders at different temperatures. In the experiments a wood particle was introduced into a pyrolysis furnace held at constant temperature. The particle mass and volume were recorded using a balance and a video camera. Uniform shrinkage slows down the pyrolysis whereas shrinking shell and cylinder models enhance the pyrolysis rate. The effect was sufficiently small to be neglected given the uncertainty about some wood physical properties.
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