| 1. |
- Andersson, Eva Ingeborg Elisabeth, 1956, et al.
(författare)
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Comparison of pulp-mill-integrated hydrogen production from gasified black liquor with stand-alone production from gasified biomass
- 2007
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 32:4, s. 399-405
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Tidskriftsartikel (refereegranskat)abstract
- When gasified black liquor is used for hydrogen production, significant amounts of biomass must be imported. This paper compares two alternative options for producing hydrogen from biomass: (A) pulp-mill-integrated hydrogen production from gasified back liquor; and (B) stand-alone production of hydrogen from gasified biomass. The comparison assumes that the same amount of biomass that is imported in Alternative A is supplied to a stand-alone hydrogen production plant and that the gasified black liquor in Alternative B is used in a black liquor gasification combined cycle (BLGCC) CHP unit. The comparison is based upon equal amounts of black liquor fed to the gasifier, and identical steam and power requirements for the pulp mill. The two systems are compared on the basis of total CO2 emission consequences, based upon different assumptions for the reference energy system that reflect different societal CO2 emissions reduction target levels. Ambitions targets are expected to lead to a more CO2–lean reference energy system, in which case hydrogen production from gasified black liquor (Alternative A) is best from a CO2 emissions’ perspective, whereas with high CO2 emissions associated with electricity production, hydrogen from gasified biomass and electricity from gasified black liquor (Alternative B) is preferable.
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| 2. |
- Andersson, Eva Ingeborg Elisabeth, 1956, et al.
(författare)
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Energy efficient upgrading of biofuel integrated with a pulp mill
- 2006
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 31:10-11, s. 1384-1394
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents and evaluates different energy efficient options for integrating drying and pelletising ofbiofuel with a modern energy efficient pulp mill process. When drying biofuel, a large amount of the heat input canoften be recovered. One option for heat recovery is to cover low-temperature heat demand in the pulping process.Alternatively available excess heat from the pulp mill can be used for drying. Both alternatives will contribute to abetter energy efficiency for the combined pulp mill and biofuel upgrading facility. Pinch analysis tools can be usedto estimate the excess heat potential at different temperature levels in the pulp mill. Three different technologies forpulp mill integrated biofuel drying were chosen for the study, namely steam drying, flue gas drying and vacuumdrying. The different technologies are evaluated on the basis of energy usage, global CO2 emissions and resultingpellets production cost, using stand-alone pellets production as a reference. The pulp mill assumed for thecalculations is the Eco-Cyclic reference pulp mill. The results of the study indicate that the most attractiveintegrated drying technology option is the flue gas dryer, using flue gases from the black liquor boiler. With theavailable flue gas stream at the reference pulp mill, a potential pellets production of 70,000 ton/yr could beachieved at a cost of 24.6 EUR/ton. The associated reduction in CO2 emissions compared to stand-alone pelletsproduction is 3136 kg/MWh-pellets.
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| 3. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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A tool for creating energy market scenarios for evaluation of investments in energy intensive industry
- 2009
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 34:12, s. 2069-2074
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Tidskriftsartikel (refereegranskat)abstract
- The energy intensive industry can be a major contributor to CO2 emissions reduction, provided that appropriate investments are made. To assess profitability and net CO2 emissions reduction potential of such investments, predictions about future energy market conditions are needed. Energy market scenarios can be used to reflect different possible future energy market conditions. This paper presents a tool for creating consistent energy market scenarios adapted for evaluation of energy related investments in energy intensive industrial processes. Required user inputs include fossil fuel prices and costsassociated with policy instruments, and the outputs are energy market prices and CO2 consequences of import/export of different energy streams (e.g. electric power and biomass fuel) from an industrial process site. The paper also presents four energy market scenarios for the medium-term future (i.e. around 2020) created using the tool.
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| 4. |
- De, S., et al.
(författare)
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Development of an artificial neural network model for the steam process of a coal biomass cofired combined heat and power (CHP) plant in Sweden
- 2007
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Ingår i: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 32:11, s. 2099-2109
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Tidskriftsartikel (refereegranskat)abstract
- The development of a model for any energy system is required for proper design, operation or its monitoring. Models based on accurate mathematical expressions for physical processes are mostly useful to understand the actual operation of the plant. However, for large systems like combined heat and power (CHP) plants, such models are usually complex in nature. The estimation of output parameters using these physical models is generally time consuming, as these involve many iterative solutions. Moreover, the complete physical model for new equipment may not be available. However, artificial neural network (ANN) models, developed by training the network with data from an existing plant, may be very useful especially for systems for which the full physical model is yet to be developed. Also, such trained ANN models have a fast response with respect to corresponding physical models and are useful for realtime monitoring of the plant. In this paper, the development of an ANN model for the biomass and coal cofired CHP plant of Visthamnsverket at Helsingborg, Sweden has been reported. The feed forward with back propagation ANN model was trained with data from this plant. The developed model is found to quickly predict the performance of the plant with good accuracy. (C) 2007 Elsevier Ltd. All rights reserved.
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| 5. |
- Ericsson, Karin
(författare)
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Co-firing - A strategy for bioenergy in Poland?
- 2007
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Ingår i: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 32:10, s. 1838-1847
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Tidskriftsartikel (refereegranskat)abstract
- Biomass provides the largest reduction of carbon dioxide (CO2) emission when it replaces coal, which is the dominating fuel in heat and electricity production in Poland. One means of replacing coal with biomass is to co-fire biofuels in an existing coal-fired boiler. This paper presents an analysis of the strengths and weaknesses of co-firing biofuels in Poland with respect to technical, environmental, economical and strategic considerations. This analysis shows that co-firing is technically and economically the most realistic option for using biofuels in the large pulverized fuel (PF) boilers in Poland. However, from an environmental perspective, co-firing of biofuels in large combined heat and power (CHP) plants and power plants provides only a small reduction in sulphur dioxide (SO2) emission per unit biofuel, since these plants usually apply some form of desulphurization technology. In order to maximize the SO2 emission reduction, biofuels should be used in district heating plants. However, co-fired combustion plants can handle disruptions in biofuel supply and are insensitive to moderate changes in fuel prices, which makes them suitable utilizers of biofuels from perennial energy crops. Co-firing could therefore play an important role in stimulating perennial crop production.
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| 6. |
- Fahlén, Elsa, 1981, et al.
(författare)
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Assessment of integration of different biomass gasification alternatives in a district-heating system
- 2009
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Ingår i: Energy. - 0360-5442. ; 34, s. 2184-2195
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Tidskriftsartikel (refereegranskat)abstract
- With increasingly stringent CO2 emission reduction targets, incentives for efficient use of limited biomass resources increase. Technologies for gasification of biomass may then play a key role given their potential for high electrical efficiency and multiple outputs; not only electricity but also bio transport fuels and district heat. The aim of this study is to assess the economic consequences and the potential for CO2reduction of integration of a biomass gasification plant into a district-heating (DH) system. The study focuses on co-location with an existing natural gas combined cycle heat and power plant in the municipal DH system of Go¨ teborg, Sweden. The analysis is carried out using a systems modeling approach. The so-called MARTES model is used. MARTES is a simulating, DH systems supply model with a detailed time slice division. The economic robustness of different solutions is investigated by using different sets of parameters for electricity price, fuel prices and policy tools. In this study, it is assumed that not only tradable green certificates for electricity but also tradable green certificates for transport fuels exist. The economic results show strong dependence on the technical solutions and scenario assumptions but in most cases a stand-alone SNG-polygeneration plant with district-heat delivery is the cost-optimal solution. Its profitability is strongly dependent on policy tools and the price relation between biomass and fossil fuels. Finally, the results show that operation of the biomass gasification plants reduces the (DH) system’s net emissions of CO2.
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| 7. |
- Fredriksson Möller, Björn, et al.
(författare)
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CO2-free power generation in combined cycles - Integration of post-combustion separation of carbon dioxide in the steam cycle
- 2006
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Ingår i: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 31:10-11, s. 1520-1532
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Tidskriftsartikel (refereegranskat)abstract
- Ever since the release of the Kyoto protocol the demand for CO2-free processes have been increasing. One of the most expanding sources of electric power in the industrialised world today is the gas-fired combined cycle, combining high efficiency and low investment cost. In this paper, the integration of a post-combustion CO2-separation unit into a combined cycle is studied from a thermodynamic and economic point-of-view. A standard dual-pressure combined cycle is chosen as a reference cycle. It is compared to a dual-pressure combined cycle and a triple-pressure combined cycle with the lowest pressure level producing steam for a CO2-separation unit. The steam pressure levels in the different cycles are optimised for maximum efficiency and minimum specific cost, respectively, using genetic algorithms. The efficiency drop due to CO2-separation is approximately 8% points, from 54 to 46%. The specific cost of the power plant is expected to increase with almost 100% and the cost of electricity with approximately 30%. In several countries a carbon dioxide tax is already introduced as an incentive for more efficient power cycles and use of fuels with lower content of coal. The result above implies that the level of such a tax would be in the order of 30% of the price of electricity to encourage CO2-free power generation.
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| 8. |
- Fredriksson Möller, Björn, et al.
(författare)
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On the off-design of a natural gas-fired combined cycle with CO2 capture
- 2007
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Ingår i: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 32:4, s. 353-359
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Tidskriftsartikel (refereegranskat)abstract
- During the last 15 years cycles with CO, capture have been in focus, due to the growing concern over our climate. Often, a natural gas fired combined cycle with a chemical absorption plant for CO, capture from the flue gases have been used as a reference in comparisons between cycles. Neither the integration of the steam production for regeneration of amines in the combined cycle nor the off-design behaviour of such a plant has been extensively Studied before. In this paper, the integration of steam production for regeneration of the amines is modelled at design load and studied in off-design conditions for a combined cycle. Different ambient conditions and part-load strategies and their influence on the cycle performance are also examined. Of particular interest is a novel strategy with the possibility of longer life of gas turbine blading, with marginal loss in efficiency. The off-design performance of the combined cycle is modelled in a rigorous Way using a gas turbine performance deck, while the boiler is calculated using simplified correlations for oft-design heat transfer and pressure drop. The steam turbine calculation is based on verified models for the flow-pressure-efficiency relations, whilst the steam condenser is based oil the HEI method.
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| 9. |
- Grönkvist, Stefan, et al.
(författare)
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Oxygen efficiency with regard to carbon capture
- 2006
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 31:15, s. 3220-3226
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Tidskriftsartikel (refereegranskat)abstract
- Carbon capture is often discussed in the literature with the sole focus on power processes, despite the fact that carbon dioxide emissions from other sources are just as relevant for the impact on the atmosphere. Furthermore, some carbon capture methods are relatively inefficient when applied to power production processes. Carbon capture should preferably be performed where the cost is as low as possible, i.e. not necessarily from power production processes. As an example, carbon capture using combustion with pure oxygen is far more energy efficient if it is used together with lime kilns or cement kilns than together with power production processes. A new concept termed "oxygen efficiency" is introduced in this paper. It describes the amount of carbon dioxide that can potentially be captured per unit of oxygen. As such, the oxygen efficiency quantifies the value of a certain unit of oxygen for carbon capture reasons. The base concept is that the energy penalty for the production of one part of oxygen is the same no matter where it is produced; hence, if this unit of oxygen can be used to capture more carbon dioxide, it is more efficient. Typically, the oxygen efficiency would be five times greater for carbon capture when utilising pure oxygen together with cement kilns rather than together with methane-fired power plants. Furthermore, the concept of oxygen efficiency illustrates the importance of considering how carbon capture methods can be utilised in the most efficient way, in addition to evaluating which carbon capture method is the most suitable for a particular technology.
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| 10. |
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