| 1. |
- Andersson, Maria, 1965-
(författare)
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Shadow prices for heat generation in time-dependent and dynamic energy systems
- 1994
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 19:12, s. 1205-1211
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Tidskriftsartikel (refereegranskat)abstract
- Shadow prices for heat generation are used to study the impact of changes in heat demand on the total system cost of an existing district-heating system in Sweden. The energy system may be considered to be both dynamic, because there is energy storage, and time-dependent since the electricity tariff is time-differentiated and the heat demand varies over the year and day. The energy system has been analysed with and without energy storage. The analysis shows that despite a reduction in system cost, the use of energy storage can result in higher shadow prices for heat generation in some time periods.
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| 2. |
- Gustafsson, Stig-Inge, et al.
(författare)
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Factorial design for energy System Models
- 1994
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 19:8, s. 905-910
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Tidskriftsartikel (refereegranskat)abstract
- Mathematical models are extensively used in energy analysis and have increased in scope as better and faster computers have become available. With complicated systems, it is difficult to predict accurate results if doubtful input data are changed. Traditionally, sensitivity analysis with a change of one or more of the parameters is used. If the influence of a change is very small, the first result is believed to be accurate. Problems may arise when sensitivity analysis is applied to a vast amount of data. The aim of this paper is to examine whether the calculation effort can be decreased by using factorial design. Our model, called Opera (Optimal Energy Retrofit Advisory), is used to find the optimal retrofit strategy for a multi-family building. The optimal solution is characterised by the lowest possible life-cycle cost. Three parameters have been studied here: length of the optimisation period, real interest rate and existing U-value for an attic floor. The first two parameters are found to influence the life-cycle cost significantly, while the last is of minor importance for this cost. We also show that factorial analysis must be used with great care because the method does not reflect the complete situation.
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| 3. |
- Gustafsson, Stig-Inge, et al.
(författare)
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Natural gas in Optimized Bivalent Heating Sytems
- 1990
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Ingår i: Energy. - 0360-5442 .- 1873-6785. ; 15:11, s. 993-999
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Tidskriftsartikel (refereegranskat)abstract
- In accordance with a public referendum held in 1980, Sweden will phase out nuclear power completely by 2010. One way to compensate for an immediate, appreciable scarcity of electric power is to construct new fossil-fuel power stations. Another is to reduce the burden on electric power by converting some end-user facilities to operate on natural gas (NG) imported from Denmark through a new pipeline to southern Sweden. We show how an optimal solution can be found for NG operation of a system incorporating an NG boiler and an electric heat pump. Electricity is priced by a time-of-use tariff (TOU) requiring a discrete optimization method. The optimal solution is characterized by the lowest life cycle cost (LCC) for the building as an energy system.
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| 9. |
- Nilsson, Lars J
(författare)
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Energy intensity trends in 31 industrial and developing countries 1950-1988
- 1993
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Ingår i: Energy. - 1873-6785. ; 18:4, s. 309-322
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Tidskriftsartikel (refereegranskat)abstract
- Trends in energy intensities for 31 countries are evaluated, over the period from 1950 to 1988, using a purchasing power parity-based GDP measure and United Nations energy statistics. With non-commercial energy included, the energy intensities of low income countries are similar to those of high income countries. Energy intensities have decreased for 15 out of the 31 countries studied. The analysis indicates that there is a level of energy intensity, between 0.25 and 0.5 toe per 1000 (1980) international dollars, to which many countries are converging. Energy use per capita increases with higher incomes, but cross-country comparisons can be misleading and inappropriate due to large differences in, for example, economic structure and climate. Electricity appears to be the energy carrier of choice for advanced economies, leading to increased use of electricity relative to other energy carriers. Electricity intensities for eight industrialized countries are evaluated. In four countries, electricity intensities have decreased in recent years. This result suggests that electricity intensities may develop similarly to how energy intensities have developed as economic structure and energy end-use efficiency continue to change.
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