| 1. |
- Andersson, Klas, 1977, et al.
(författare)
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Process evaluation of an 865 MWe lignite fired O2/CO2 power plant
- 2006
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 47:18-19, s. 3487-3498
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Tidskriftsartikel (refereegranskat)abstract
- In order to reduce emissions of carbon dioxide from large point sources, new technologies can be used in capture plants for combustion of fossil fuel for subsequent capture and storage of CO2. One such technology is the O2/CO2 combustion process (also termed oxy-fuel combustion) that combines a conventional combustion process with a cryogenic air separation process so that the fuel is burned in oxygen and recycled flue gas, yielding a high concentration of CO2 in the flue gas, which reduces the cost for its capture. In this work, the O2/CO2 process is applied using commercial data from an 865 MWe lignite fired reference power plant and large air separation units (ASU). A detailed design of the flue gas treatment pass, integrated in the overall process layout, is proposed. The essential components and energy streams of the two processes have been investigated in order to evaluate the possibilities for process integration and to determine the net efficiency of the capture plant. The electricity generation cost and the associated avoidance cost for the capture plant have been determined and compared to the reference plant with investment costs obtained directly from industry. Although an existing reference power plant forms the basis of the work, the study is directed towards a new state of the art lignite fired O2/CO2 power plant. The boiler power of the O2/CO2 plant has been increased to keep the net output of the capture and the reference plant similar. With the integration possibilities identified, the net efficiency becomes 33.5%, which should be compared to 42.6% in the reference plant. With a lignite price of 5.2 $/MWh and an interest rate of 10%, the electricity generation cost increases from 42.1 to 64.3 $/MWh, which corresponds to a CO2 avoidance cost of 26 $/ton CO2.
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| 2. |
- Assefa, Getashew, et al.
(författare)
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Technology assessment of thermal treatment technologies using ORWARE
- 2005
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 46:5, s. 797-819
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Tidskriftsartikel (refereegranskat)abstract
- A technology assessment of thermal treatment technologies for wastes was performed in the form of scenarios of chains of technologies. The Swedish assessment tool, ORWARE, was used for the assessment. The scenarios of chains of thermal technologies assessed were gasification with catalytic combustion, gasification with flame combustion, incineration and landfilling. The landfilling scenario was used as a reference for comparison. The technologies were assessed from ecological and economic points of view. The results are presented in terms of global warming potential, acidification potential, eutrophication potential, consumption of primary energy carriers and welfare costs. From the simulations, gasification followed by catalytic combustion with energy recovery in a combined cycle appeared to be the most competitive technology from an ecological point of view. On the other hand, this alternative was more expensive than incineration. A sensitivity analysis was done regarding electricity prices to show which technology wins at what value of the unit price of electricity (SEK/kW h). Within this study, it was possible to make a comparison both between a combined cycle and a Rankine cycle (a system pair) and at the same time between flame combustion and catalytic combustion (a technology pair). To use gasification just as a treatment technology is not more appealing than incineration, but the possibility of combining gasification with a combined cycle is attractive in terms of electricity production. This research was done in connection with an empirical R&D work on both gasification of waste and catalytic combustion of the gasified waste at the Division of Chemical Technology, Royal Institute of Technology (KTH), Sweden.
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| 3. |
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| 4. |
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| 5. |
- Eriksson, Marcus, 1974, et al.
(författare)
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Heat pumps and tradable emission permits: On the carbon dioxide emissions of technologies that cross a tradable emission market boundary
- 2006
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 47:20, s. 3510-3518
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Tidskriftsartikel (refereegranskat)abstract
- Since January 2005, there is a system with tradable emission permits/allowances in the European Union. Currently, power producers and district heating plants are included in the system, but not the residential sector. In this analytical study, it is discussed how a separation between a trading sector, in which power producers are participating and a nontrading residential sector affect carbon dioxide emissions consequences from heat pumps in households. It is concluded that a replacement of heat pumps in the residential sector results in a leakage of emissions. The emission target in the trading sector is partly achieved at the expense of increased emissions in the residential sector.
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| 6. |
- Fiaschi, D, et al.
(författare)
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The air membrane-ATR integrated gas turbine power cycle : A method for producing electricity with low CO2 emissions
- 2005
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 46:15-16, s. 2514-2529
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Tidskriftsartikel (refereegranskat)abstract
- The air membrane-auto thermal reforming (AM-ATR) gas turbine cycle combines features of the R-ATR power cycle, introduced at the University of Florence, with ceramic, air separation membranes to achieve a novel combined cycle process with fuel decarbonisation and near-zero CO2 emissions. Within this process, the natural gas fuel is converted to H-2 and CO through the auto thermal reforming process (ATR), i.e. combined partial oxidation and steam methane reforming, within the air separation membrane reactor. In a subsequent process unit, the H-2 Content of the reformed fuel is enriched by the well known CO-CO2 shift reaction. This fuel is then sent to an amine based carbon dioxide removal unit and, finally, to two combustors: the first one is located upstream of the membrane reformer (in order to achieve the required working temperature) and the second one is downstream of the membrane to reach the desired turbine inlet temperature (TIT). The main advantage of the proposed concept over other decarbonisation processes is the coupling of the membrane and the ATR reactor. This coupling greatly reduces the mass flow of syngas with respect to the air blown ATR contained in the previously proposed R-ATR, thus lowering the size of the syngas treatment section. Furthermore, as the oxygen production is integrated at high temperatures in the power cycle, the efficiency penalty of producing oxygen is much smaller than for the traditional cryogenic oxygen separation. The main advantages over other integrated GT-membrane concepts are the lower membrane operating temperature, lower levels of required air separation at high partial pressure driving forces (leading to lower membrane surface areas) and the possibility to achieve a higher TIT with top firing without increasing CO2 emissions. When compared to power plants with tail end CO2 separation, the CO2 removal process treats a gas at pressure and with a significantly higher CO2 concentration than that of gas turbine exhausts, which allows a compact carbon dioxide removal unit with a lower energy penalty. Starting from the same basis, various configurations were considered and optimised, all of which targeted a 65 MW power output combined cycle. The efficiency level achieved is around 45% (including recompression of the separated CO2), which is roughly 10% less than the reference GT-CC plant (without CO2 removal). A significant part of the efficiency penalty (4.3-5.6% points) is due to the fuel reforming, whereas further penalties come from the recompression units, loss of working fluid through the expander and the steam extracted for the ATR reactor and CO2 separation. The specific CO2 emissions of the MCM-ATR are about 120 kg CO2/kWh, representing 30% of the emissions without CO2 removal. This may be reduced to 10-15% with a better design of the shift reactors and the CO2 removal unit. Compared to other concepts with air membrane technology, such as the AZEP concept, the efficiency loss is much greater when used for fuel de-carbonisation than for previous integration options.
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| 7. |
- Gabrielaitiene, Irina, et al.
(författare)
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Modelling temperature dynamics of a district heating system in Naestved, Denmark - A case study
- 2007
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 48:1, s. 78-86
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Tidskriftsartikel (refereegranskat)abstract
- Modelling the temperature dynamics of a district heating system is typically validated for a single pipe or a system with limited information about dynamic consumer behaviour. In the present work, time dependent consumer data from the Naestved district heating system was used to investigate the ability of modelling tools to represent the temperature profile distortion throughout an entire heating system network. The Naestved district heating subsystem was modelled by two approaches (the node method developed at the Technical University of Denmark and the software TERMIS), and these modelling results were compared with measured data. The results indicate that the discrepancies between the predicted and measured temperatures are pronounced for consumers located in pipelines at distant pipelines containing numerous bends and fittings. Additionally, it was found that representing the consumer behaviour on an annual average basis introduced a deviation between the predicted and the measured return temperatures at the heat source. (c) 2006 Elsevier Ltd. All rights reserved.
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| 8. |
- Gabrielaitiene, Irina, et al.
(författare)
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Modelling temperature dynamics of a district heating system in Naestved, Denmark – a case study
- 2006
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Ingår i: Energy Conversion and Management. - 0196-8904. ; 48:1
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Tidskriftsartikel (refereegranskat)abstract
- Modelling the temperature dynamics of a district heating system is typically validated for a single pipe or a system with limited information about dynamic consumer behaviour. In the present work, time dependent consumer data from the Naestved district heating system was used to investigate the ability of modelling tools to represent the temperature profile distortion throughout an entire heating system network. The Naestved district heating subsystem was modelled by two approaches (the node method developed at the Technical University of Denmark and the software TERMIS), and these modelling results were compared with measured data. The results indicate that the discrepancies between the predicted and measured temperatures are pronounced for consumers located in pipelines at distant pipelines containing numerous bends and fittings. Additionally, it was found that representing the consumer behaviour on an annual average basis introduced a deviation between the predicted and the measured return temperatures at the heat source.
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| 9. |
- Gustafsson, Stig-Inge
(författare)
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Refurbishment of industrial buildings
- 2006
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 47:15-16, s. 2223-2239
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Tidskriftsartikel (refereegranskat)abstract
- When a building is subject for refurbishment, there is a golden opportunity to change its behavior as an energy system. This paper shows the importance of careful investigations of the processes, the climate shield and the heating systems already present in the building before measures are implemented in reality. A case study is presented dealing with a carpentry factory. The building is poorly insulated according to standards today, and initially it was assumed that a better thermal shield would be of vital importance in order to reach optimal conditions. Instead, it is shown that the main problem is the ordinary heating system. This uses steam from a wood chips boiler and the wood chips come from the manufacturing processes. These wood chips are, therefore, a very cheap fuel. The boiler had, during decades of use, slowly degraded into a poor state. Hence, aero-tempers using expensive electricity have been installed to remedy the situation. These use not only expensive kWh but also very expensive kW due to the electricity tariff. It is shown that electricity for heating purposes must be abandoned and further, that this could be achieved at a surprisingly small cost. By stopping a large waste of steam, it was possible to find resources, in the form of unspent money, for further mending the existing heating system. Not only economy but also environmental hazards in the form of CO2 emissions urges us to abandon electricity and instead use heat from cheap biomass fired boilers. Such equipment saves environment at the same time it saves money. © 2006 Elsevier Ltd. All rights reserved.
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| 10. |
- Hektor, Erik, 1978, et al.
(författare)
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Future CO2 removal from pulp mills - Process integration consequences
- 2007
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 48:11, s. 3025-3033
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Tidskriftsartikel (refereegranskat)abstract
- Earlier work has shown that capturing the CO2 from flue gases in the recovery boiler at a pulp mill can be a cost effective way of reducing mill CO2 emissions. However, the CO2 capture cost is very dependent on the fuel price. In this paper, the potential for reducing the need for external fuel and thereby the possibility to reduce the cost for capturing the CO2 is investigated. The reduction is achieved using thermal process integration. In alternative 1, the mill processes are integrated and a steam surplus made available for CO2 capture, but still there is a need for external fuel. In alternative 2, the integration is taken one step further, the reboiler is fed with MP steam, and the waste heat from the absorption unit is used for generation of LP steam needed at the mill. The avoidance costs are in both cases lower than before the process integration. The avoidance cost in alternative 1 varies between 25.4 and 30.7 EUR/tonne CO2 depending on the energy market parameters. For alternative 2, the cost varies between 22.5 and 27.2 EUR/tonne CO2. With tough CO2 reduction targets and corresponding high CO2 emission costs, the annual earnings can be substantial, 18.6 MEUR with alternative 1 and 21.2 MEUR with alternative 2.
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