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- Bojler Görling, Martin, 1984-
(author)
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Energy system evaluation of thermo-chemical biofuel production : Process development by integration of power cycles and sustainable electricity
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Fossil fuels dominate the world energy supply today and the transport sector is no exception. Renewable alternatives must therefore be introduced to replace fossil fuels and their emissions, without sacrificing our standard of living. There is a good potential for biofuels but process improvements are essential, to ensure efficient use of a limited amount of biomass and better compete with fossil alternatives. The general aim of this research is therefore to investigate how to improve efficiency in biofuel production by process development and co-generation of heat and electricity. The work has been divided into three parts; power cycles in biofuel production, methane production via pyrolysis and biofuels from renewable electricity.The studies of bio-based methanol plants showed that steam power generation has a key role in the large-scale biofuel production process. However, a large portion of the steam from the recovered reaction heat is needed in the fuel production process. One measure to increase steam power generation, evaluated in this thesis, is to lower the steam demand by humidification of the gasification agent. Pinch analysis indicated synergies from gas turbine integration and our studies concluded that the electrical efficiency for natural gas fired gas turbines amounts to 56-58%, in the same range as for large combined cycle plants. The use of the off-gas from the biofuel production is also a potential integration option but difficult for modern high-efficient gas turbines. Furthermore, gasification with oxygen and extensive syngas cleaning might be too energy-consuming for efficient power generation.Methane production via pyrolysis showed improved efficiency compared with the competing route via gasification. The total biomass to methane efficiency, including additional biomass to fulfil the power demand, was calculated to 73-74%. The process benefits from lower thermal losses and less reaction heat when syngas is avoided as an intermediate step and can handle high-alkali fuels such as annual crops.Several synergies were discovered when integrating conventional biofuel production with addition of hydrogen. Introducing hydrogen would also greatly increase the biofuel production potential for regions with limited biomass resources. It was also concluded that methane produced from electrolysis of water could be economically feasible if the product was priced in parity with petrol.
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| 4. |
- Görling, Martin, 1984-, et al.
(author)
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Bio-methane via fast pyrolysis of biomass
- 2013
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In: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 112:SI, s. 440-447
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Journal article (peer-reviewed)abstract
- Bio-methane, a renewable vehicle fuel, is today produced by anaerobic digestion and a 2nd generation production route via gasification is under development. This paper proposes a poly-generation plant that produces bio-methane, bio-char and heat via fast pyrolysis of biomass. The energy and material flows for the fuel synthesis are calculated by process simulation in Aspen Plus®. The production of bio-methane and bio-char amounts to 15.5. MW and 3.7. MW, when the total inputs are 23. MW raw biomass and 1.39. MW electricity respectively (HHV basis). The results indicate an overall efficiency of 84% including high-temperature heat and the biomass to bio-methane yield amounts to 83% after allocation of the biomass input to the final products (HHV basis). The overall energy efficiency is higher for the suggested plant than for the gasification production route and is therefore a competitive route for bio-methane production.
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| 5. |
- Görling, Martin, et al.
(author)
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Increased Power Generation by Humidification of Gasification Agent in Biofuel Production
- 2010
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In: World Renewable Energy Congress XI.
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Conference paper (peer-reviewed)abstract
- The second generation biofuels are based on gasification of waste and non-food crops. A mix of oxygen and steam is used as gasification agent. A drawback when mixing the two pure streams of oxygen and steam is that exergy is lost. The gasification process is often pressurized; which implies that both the oxygen and the steam must have higher pressure to enable feeding. The gasification process is therefore one of the main internal steam uses. However, if the steam injected can be replaced or decreased in pressure level, power generation could be significantly increased. This study shows that the power penalty can be reduced by humidification of the gasification agent compared to steam injection. The power penalty can be reduced by more than 10% when using humidification process. The power penalty is reduced by even more, 18-25%, when also using a pre-humidifier driven by latent heat recovered after the methanisation.
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| 6. |
- Görling, Martin, 1984-, et al.
(author)
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Integration Feasibilities for Combined Cycles in Biofuel Production
- 2011
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In: Proceedings of the 24th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2011. - : Nis University. - 9788660550165 ; , s. 3498-3508
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Conference paper (peer-reviewed)abstract
- The aim of this paper is to evaluate the opportunities for gas turbine integration into biofuel production. When producing biofuels via gasification, a significant amount of the input of chemical energy is converted to reaction heat. A steam cycle is therefore used to recover the heat to useful power, but despite that, the plant often remains net users of electricity. To further enhance the production several studies suggest integration of gas turbines, often fired with offgas from the fuel synthesis. The excess of low level heat in the gas turbine exhaust is successfully integrated in the steam cycle which creates integration synergies. Gasification of biomass for fuel synthesis generally implies that oxygen is used as gasification agent. Despite the synergies in the joint steam cycle, the positive effects are outweighed by the energy penalty from oxygen production. Conclusively, serial production of biofuel and power is not beneficial. More interesting is the integrating of a parallel, air-blown gasifier to produce syngas for the gas turbine. Also the natural gas fired gas turbines have successfully been integrated.
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| 7. |
- Görling, Martin, et al.
(author)
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Integration of hybrid cycles in bio-methanol production
- 2010
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In: Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, ECOS 2010. - : Åbo Akademi University Press. - 9781456303112 ; , s. 119-125
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Conference paper (peer-reviewed)abstract
- In bio-based methanol production approximately 60% of the biomass energy content is converted into methanol, the remaining part can be recovered as thermal heat. Efficient utilization of the thermal heat is difficult in stand-alone methanol plants. The overall efficiency is to a large extent dependent on the further conversion of power due to the significant quantity of excess heat. Heat can be recovered in a steam cycle but due to poor steam data energy efficiency is low. This paper therefore proposes the integration of a natural gas fired gas turbine. Simulations of the hybrid cycle in methanol production have shown good improvements. The total electrical efficiency is increased by 1.4-2.4 percentage points, depending on the fuel mix. The electrical efficiency for the natural gas used in the hybrid plant is 56-58%, which is in the same range as in large-scale combined cycle plants. A bio-methanol plant with a hybrid power cycle is therefore a competitive production route for both biomass and natural gas.
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| 8. |
- Görling, Martin, et al.
(author)
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Integration of Hybrid Cycles in Bio-Methanol Production
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In: Environmental Impact of Energy System.
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Journal article (other academic/artistic)abstract
- In bio-based methanol production approximately 60% of the biomass energy content is converted into methanol, the remaining part can be recovered as thermal heat. Efficient utilization of the thermal heat is difficult in stand-alone methanol plants. The overall efficiency is to a large extent dependent on the further conversion of power due to the significant quantity of excess heat. Heat can be recovered in a steam cycle but due to poor steam data energy efficiency is low. This paper therefore proposes the integration of a natural gas fired gas turbine. Simulations of the hybrid cycle in methanol production have shown good improvements. The total electrical efficiency is increased by 1.4-2.4 percentage points, depending on the fuel mix. The electrical efficiency for the natural gas used in the hybrid plant is 56-58%, which is in the same range as in large-scale combined cycle plants. A bio-methanol plant with a hybrid power cycle is therefore a competitive production route for both biomass and natural gas.
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| 9. |
- Görling, Martin, 1984-
(author)
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Turbomachinery in Biofuel Production
- 2011
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Licentiate thesis (other academic/artistic)abstract
- The aim for this study has been to evaluate the integration potential of turbo-machinery into the production processes of biofuels. The focus has been on bio-fuel produced via biomass gasification; mainly methanol and synthetic natural gas. The research has been divided into two parts; gas and steam turbine applications. Steam power generation has a given role within the fuel production process due to the large amounts of excess chemical reaction heat. However, large amounts of the steam produced are used within the production process and is thus not available for power production. Therefore, this study has been focused on lowering the steam demand in the production process, in order to increase the power production. One possibility that has been evaluated is humidification of the gasification agent in order to lower the demand for high quality steam in the gasifier and replace it with waste heat. The results show that the power penalty for the gasification process could be lowered by 18-25%, in the specific cases that have been studied. Another step in the process that requires a significant amount of steam is the CO2-removal. This step can be avoided by adding hydrogen in order to convert all carbon into biofuel. This is also a way to store hydrogen (e.g. from wind energy) together with green carbon. The results imply that a larger amount of sustainable fuels can be produced from the same quantity of biomass. The applications for gas turbines within the biofuel production process are less obvious. There are large differences between the bio-syngas and natural gas in energy content and combustion properties which are technical problems when using high efficient modern gas turbines. This study therefore proposes the integration of a natural gas fired gas turbine; a hybrid plant. The heat from the fuel production and the heat recovery from the gas turbine flue gas are used in a joint steam cycle. Simulations of the hybrid cycle in methanol production have shown good improvements. The total electrical efficiency is increased by 1.4-2.4 percentage points, depending on the fuel mix. The electrical efficiency for the natural gas used in the hybrid plant is 56-58%, which is in the same range as in large-scale combined cycle plants. A bio-methanol plant with a hybrid power cycle is consequently a competitive production route for both biomass and natural gas.
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| 10. |
- Larsson, Mårten, et al.
(author)
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Bio-methane upgrading of pyrolysis gas from charcoal production
- 2013
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In: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 3, s. 66-73
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Journal article (peer-reviewed)abstract
- This article presents a novel route for bio-methane synthesis utilizing pyrolysis gas from charcoal production. It is a retrofit option that may increase overall process efficiency in charcoal production while adding a valuable product. The pyrolysis gas from charcoal production can be used for bio-methane production instead of burning, while the required heat for the charcoal production is supplied by additional biomass. The aim is to evaluate the energy efficiency of bio-methane upgrading from two types of charcoal plants, with and without recovery of liquid by-products (bio-oil). Aspen simulations and calculations of the energy and mass balances are used to analyse the system. The yield of bio-methane compared to the import of additional biomass is estimated to be 81% and 85% (biomass to bio-methane yield) for the syngas case and the pyrolysis vapour case, respectively. When the biomass necessary to produce the needed electricity (assuming ηel = 33%) is included, the yields amount to 65% and 73%. The results show that the suggested process is a competitive production route for methane from lignocellulosic biomass.
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