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- Djuric Ilic, Danica, et al.
(författare)
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Integration of biofuel production into district heating - part I : an evaluation of biofuel production costs using four types of biofuel production plants as case studies
- 2014
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 69, s. 176-187
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Tidskriftsartikel (refereegranskat)abstract
- This paper evaluates the effects on profitability of biofuel production if biofuel producers would sell the waste heat from the production to a local district heating system. All analyses have been performed considering four different technology cases for biofuel production. Two technology cases include ethanol production which is followed by by-production of raw biogas. This biogas can be upgraded and sold as biofuel (the first technology case) or directly used for combined heat and power production (the second technology case). The third and the fourth technology cases are Fischer-Tropsch diesel and dimethyl ether production plants based on biomass gasification. Two different district heating price levels and two different future energy market scenarios were considered. The sensitivity analyses of the discount rate were performed as well.In the case of energy market conditions, the profitability depends above all on the price ratio between biomass (used as the feedstock for biofuel production) and crude oil (used as the feedstock for fossil diesel and gasoline production). The reason for this is that the gate biofuel prices (the prices on which the biofuel would be sold) were calculated assuming that the final prices at the filling stations are the same as the prices of the replaced fossil fuel. The price ratios between biomass and district heating, and between biomass and electricity, also have an influence on the profitability, since higher district heating and electricity prices lead to higher revenues from the heat/electricity by-produced.Due to high biofuel (ethanol + biogas) efficiency, the ethanol production plant which produces upgraded biogas has the lowest biofuel production costs. Those costs would be lower than the biofuel gate prices even if the support for transportation fuel produced from renewable energy sources were not included. If the raw biogas that is by-produced would instead be used directly for combined heat and power production, the revenues from the electricity and heat would increase, but at the same time the biofuel efficiency would be lower, which would lead to higher production costs. On the other hand, due to the fact that it has the highest heat efficiency compared to the other technologies, the ethanol production in this plant shows a high sensitivity to the district heating price level, and the economic benefit from introducing such a plant into a district heating system is most obvious. Assuming a low discount rate (6%), the introduction of such a plant into a district heating system would lead to between 28% and 52% (depending on the district heating price level and energy market scenario) lower biofuel production costs. Due to the lower revenues from the heat and electricity co-produced, and higher capital investments compared to the ethanol production plants, Fischer-Tropsch diesel and dimethyl ether productions are shown to be profitable only if high support for transportation fuel produced from renewable energy sources is included.The results also show that an increase of the discount rate from 6% to 10% does not have a significant influence on the biofuel production costs. Depending on the biofuel production plant, and on the energy market and district heating conditions, when the discount rate increases from 6% to 10%, the biofuel production costs increase within a range from 2.2% to 6.8%.
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- Gorschek, Tony, et al.
(författare)
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A controlled empirical evaluation of a requirements abstraction model
- 2007
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Ingår i: Information and Software Technology. - Newton, MA : Elsevier BV. - 0950-5849 .- 1873-6025. ; 49:7, s. 790-805
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Tidskriftsartikel (refereegranskat)abstract
- Requirement engineers in industry are faced with the complexity of handling large amounts of requirements as development moves from traditional bespoke projects towards market-driven development. There is a need for usable and useful models that recognize this reality and support the engineers in a continuous effort of choosing which requirements to accept and which to dismiss off hand using the goals and product strategies put forward by management. This paper presents an evaluation of such a model that is built based on needs identified in industry. The evaluation's primary goal is to test the model's usability and usefulness in a lab environment prior to large scale industry piloting, and is a part of a large technology transfer effort. The evaluation uses 179 subjects from three different Swedish Universities, which is a large portion of the university students educated in requirements engineering in Sweden during 2004 and 2005. The results provide a strong indication that the model is indeed both useful and usable and ready for industry trials. © 2006 Elsevier B.V. All rights reserved.
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- Wirandi, Jenny, et al.
(författare)
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Human factor validation in an industrial measurement system
- 2008
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Ingår i: Measurement. - : Elsevier BV. - 0263-2241 .- 1873-412X. ; 41:7, s. 705-718
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Forskningsöversikt (refereegranskat)abstract
- The object of this study is to determine how people interpret measurement data, which factors influence their interpretation and which do not. This study forms part of an investigation series undertaken at the paper pulp company Södra Cell in Sweden (N = 1200 employees), the investigated parameter being "paper pulp quality". The findings presented in the study are the outcomes of a questionnaire that was repeated four times (n1 = 54, n2 = 53, n3 = 43, n4 = 38), an interview (ni = 32) and regular group discussions that included 10 people (nd = 10) and that took place once a month over a three-year period. In order to quantify the quality of the product - paper pulp - different measurements must be combined. This study reveals that different employees prefer different parameters for the quantification of paper pulp quality. This study furthermore shows that there is a correlation between the employees' choice of parameters and their belonging to a particular pulp mill within the company. We also found that external factors, e.g. the opinion of authorities, affected which parameters were favoured when product quality was determined. Furthermore, the data analysis indicates that there is a correlation between the job-position of employees and the way they interpret measurement data related to product quality. Controllers and operators make similar judgments, with the exception of chemists whose opinions appear to deviate. However, the greatest variation found in the study is related to the individual person - independently of education or physical or psychological condition. The study finally proposes a number of preventive measures to improve the uniformity and reliability of measurements conducted at a process company, the most important of which is improved education of all employees who are in a position to influence product quality. © 2007 Elsevier Ltd. All rights reserved.
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- Wirandi, Jenny, et al.
(författare)
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Problem of applying modern uncertainty concepts to the measurement of instrument-specific parameters
- 2006
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 55:3, s. 700-705
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a number of problems that occur when applying the Guide to the Expression of Uncertainty in Measurement (GUM) to modern instruments. These instruments are often automatic, which makes it complicated to evaluate the uncertainty components in each measurement step because it is difficult to control and analyze them. Many of these instruments try to quantify instrument-specific parameters, which are difficult to compare with others that have the same dimension but are measured using other techniques. Often, these parameters lack traceable calibration, which may result in a large uncertainty component. This paper also considers the human aspect of the measurement process. © 2006 IEEE.
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