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1.	Börjesson, Pål, et al. (author) Regional Production and Utilisation of Biomass in Sweden 1996 In: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 21:9, s. 747-764 Journal article (peer-reviewed)abstract Regional production and utilization of biomass in Sweden is analysed, considering the potential of replacing fossil fuels and producing new electricity. Extensive utilization of biomass will decrease biomass-transportation distances. The average distance for biomass transportation to a large-scale conversion plant suitable for electricity or methanol production will be 30–42 km when the conversion plant is located in the centre of the biomass production area. The total energy efficiency of biomass production and transportation will be 95–97% and the emissions of air pollutants will be small. In areas where energy crops from agriculture constitute the main part of the biomass, the transportation distance will be two to three times shorter than in areas where logging residues from forestry dominate. When present Swedish fossil-fuel use for heat and electricity production is replaced, more than 75% of the biomass required can be produced locally within the county. The average transportation distance of the remaining part will be between 130 and 240 km, increasing the cost of this biomass by 15–20%. Increased use of biomass by 430 PJ/yr, the estimated potential for increased utilization of energy crops, logging residues and straw, will lead to an excess of about 200 PJ/yr biomass after fossil fuels for electricity and heat production have been replaced. This biomass could be used for methanol or electricity production. The production of biomass-based methanol will lead to a low demand for transportation, as the methanol produced from local biomass can mainly be used locally to replace petrol and diesel. If the biomass is used for electricity production, however, the need for transportation will increase if the electricity is cogenerated in district heating systems, as such systems are usually located in densely populated areas with a deficit of biomass. About 60% of the biomass used for cogenerated electricity must be transported, on average, 230 km. Changing transportation mode when transporting biomass over large distances, compared with short distances, however, will lead to rather low specific transportation costs and environmental impact, as well as high energy efficiency. Replacing fossil fuels with biomass for heat and electricity production is typically less costly and leads to a greater reduction in CO2 emission than substituting biomass for petrol and diesel used in vehicles. Also, cogeneration of electricity and heat is less costly and more energy efficient than separate electricity and heat production.
2.	Christiansson, Lena (author) Time Dynamics of Electricity Demand in Air-Distribution Systems for Commercial Buildings in Sweden 1996 In: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 21:10, s. 879-888 Journal article (peer-reviewed)abstract This paper illustrates the potential for reducing future electricity demand for air distribution in commercial buildings in Sweden. We have developed a general, quantitative, scenario-based framework to describe electricity demand for air distribution and to analyze how governmental and utility-sponsored policy measures affect electricity demand. The results suggest that higher electricity prices will not be very effective in reducing electricity demand, whereas significant electricity savings can be achieved by implementing desirable policy programs.
3.	Gustavsson, Leif, et al. (author) Heating Detached Houses in Urban Areas 2003 In: Energy. - 0360-5442 .- 1873-6785. ; 28:8, s. 851-875 Journal article (peer-reviewed)abstract District heating systems using cogeneration, as well as local fuel-based and electric heating systems for detached houses, are analysed. The analysis includes the whole energy system, from the natural resource to the end user, with respect to primary energy use, emission and cost. The end-use technologies studied are heat pumps, resistance heaters and boilers. It was assumed that the base-load electricity, except for the cogenerated electricity, was produced in stand-alone power plants using wood chips or natural gas, while peak-load electricity and fuel used for transportation were produced from crude oil. The heat pump and district heating systems are found to be most energy efficient, followed by the local fuel-based systems. The wood-fuel-based systems emit about one tenth of the greenhouse gases emitted by the natural-gas-based systems. The sulphur and nitrogen oxide emission, however, is higher for wood-fuel-based systems. Systems based on natural gas are less expensive than the corresponding wood-fuel-based systems. Decarbonization and carbon dioxide sequestration, however, do not reduce the carbon dioxide emission to the low level of the wood-fuel-based systems and, in addition, make the natural-gas-based systems more expensive than the wood-fuel-based systems.
4.	Johansson, Bengt, et al. (author) Energy and environmental costs for electric vehicles using CO2-neutral electricity in Sweden 2000 In: Energy. - 0360-5442 .- 1873-6785. ; 25:8, s. 777-792 Journal article (peer-reviewed)abstract Electric vehicles (EVs) may provide an alternative for CO2-neutral transportation services. This article analyses the cost of energy and emissions from using electricity produced from Swedish renewable energy sources in electric vehicles, and compares it with the cost of an alternative in which biomass-based methanol is used in internal combustion engine vehicles (ICEVs). These costs do not include vehicle and battery costs. Cost estimates of electricity, calculated using a marginal cost perspective, include production costs as well as the cost of distribution and vehicle recharging. The energy cost per km for vehicles using electricity is calculated to be 30-70% of the cost of biomass-based methanol, depending on the general level of electricity demand, the need for grid upgrading, and the assumed cost of biomass-based methanol. A high general electricity demand in society would require expensive condensing plants to supply the vehicles, whereas with a lower demand, cheaper cogeneration and wind power plants could be utilised. An electric vehicle, used as the average Swedish car, would, during its lifetime, have energy and environmental costs 30 000-40 000 SEK ($4000-5400) lower than the current state-of-the art ICEVs using biomass-based methanol. An electric vehicle used mainly in the city centre might have energy and environmental costs which are 130 000-140 000 SEK ($17 000-19 000) lower than a current methanol-fuelled car. With future improvements in the energy efficiency and environmental performance of ICEVs the difference will be significantly reduced. If battery costs were included in the cost calculations, EVs would not be cost competitive with future ICEVs, even if battery costs are reduced to $100/kWh. (C) 2000 Elsevier Science Ltd. All rights reserved.Electric vehicles (EVs) may provide an alternative for CO2-neutral transportation services. This article analyses the cost of energy and emissions from using electricity produced from Swedish renewable energy sources in electric vehicles, and compares it with the cost of an alternative in which biomass-based methanol is used in internal combustion engine vehicles (ICEVs). These costs do not include vehicle and battery costs. Cost estimates of electricity, calculated using a marginal cost perspective, include production costs as well as the cost of distribution and vehicle recharging. The energy cost per km for vehicles using electricity is calculated to be 30-70% of the cost of biomass-based methanol, depending on the general level of electricity demand, the need for grid upgrading, and the assumed cost of biomass-based methanol. A high general electricity demand in society would require expensive condensing plants to supply the vehicles, whereas with a lower demand, cheaper cogeneration and wind power plants could be utilized. An electric vehicle, used as the average Swedish car, would, during its lifetime, have energy and environmental costs 30 000-40 000 SEK ($4000-5400) lower than the current state-of-the art ICEVs using biomass-based methanol. An electric vehicle used mainly in the city centre might have energy and environmental costs which are 130 000-140 000 SEK ($17 000-19 000) lower than a current methanol-fuelled car. With future improvements in the energy efficiency and environmental performance of ICEVs the difference will be significantly reduced. If battery costs were included in the cost calculations, EVs would not be cost competitive with future ICEVs, even if battery costs are reduced to $100/kWh.
5.	Johansson, Bengt (author) Will Swedish Biomass be Sufficient for Future Transportation Fuel Demands? 1996 In: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 21:12, s. 1059-1069 Journal article (peer-reviewed)abstract There is a potential to increase the annual use of biomass in Sweden by 125 TWh between 1994 and 2015. 125 TWh of biomass would satisfy most of the transportation-fuel demand in Sweden in 2015. Even if the biomass is primarily used for heat and electricity production, a significant fraction will be available for transportation-fuel production, if other non-fossil energy sources are utilized for electricity production and/or substantial energy-efficiency improvements are realized. Improved energy efficiency and the use of renewable energy sources will be required in all sectors to achieve CO2 emission reductions greater than 50%.
6.	Andersson, Maria, 1965- (author) Shadow prices for heat generation in time-dependent and dynamic energy systems 1994 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 19:12, s. 1205-1211 Journal article (peer-reviewed)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.
7.	Dai, X W, et al. (author) Pyrolysis of waste tires in a circulating fluidized-bed reactor 2001 In: Energy. - 0360-5442 .- 1873-6785. ; 26:4, s. 385-399 Journal article (peer-reviewed)abstract Using a circulating fluidized bed (CFB) as the main reactor, an integrated process development unit was operated aiming at the pyrolysis of waste tires. The main chemical processes in the CFB can be divided into two zones corresponding to pyrolysis and secondary reactions. The pyrolysis of tire powder was carried out at various pyrolysis temperatures, particle sizes of tire powder and feed positions. The effects of temperature, residence time and heating rate on pyrolysis were analyzed based on the experimental data. The main trends are that (1) a long residence time contributes to secondary reactions and (2) lower temperature and heating rate favor carbonization, which reduces the oil yield. Analysis of the pyrolytic oil shows that the predominant components are aromatics, followed by alkanes, non-hydrocarbons and asphalt.
8.	Gong, Mei (author) Optimization of industrial energy systems by incorporating feedback loops into the MIND method 2003 In: Energy. - 0360-5442 .- 1873-6785. ; 28:15, s. 1655-1669 Journal article (peer-reviewed)abstract The MIND (Method for analysis of INDustrial energy system) method has been developed for multi-period cost optimization of industrial energy systems. Existing industrial processes can be represented at the desired level of accuracy, i.e. one modeling unit may represent a part of the production process or the whole plant. The optimization method includes both energy and material flows. Nonlinear relations, energy conversion efficiencies and investment costs are linearized by mixed-integer linear programming. A flexible time-scale facilitates the performance of long- and short-term analyses. In order to meet the requirements with regard to sustainable development, the recycling of energy and material flows is becoming more common in many industrial processes. The recycling or reuse of energy and material is managed by feedback loops, which are incorporated into the original MIND method to improve the model and reduce the calculation time. The improved MIND/F method (MIND method with feedback loops) model is applied to a pulp and paper mill in Sweden. A comparison between the original MIND method with manual handling of the feedback loops and the MIND/F method gives highly satisfactory results. Cost optimization using the improved MIND method is well within the given accuracy and computer time and manual calculation time are both reduced considerably. The reuse of energy and material resources is not only an economic advantage, but also implies a reduction of the environmental impact.
9.	Gustafsson, Stig-Inge, et al. (author) Factorial design for energy System Models 1994 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 19:8, s. 905-910 Journal article (peer-reviewed)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.
10.	Gustafsson, Stig-Inge, et al. (author) Natural gas in Optimized Bivalent Heating Sytems 1990 In: Energy. - 0360-5442 .- 1873-6785. ; 15:11, s. 993-999 Journal article (peer-reviewed)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.
11.	Gustafsson, Stig-Inge, et al. (author) Optimal heating-system retrofits in residential buildings 1997 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 22:9, s. 867-874 Journal article (peer-reviewed)abstract The optimal heating-system-retrofit strategy for existing buildings differs due to varying prices of energy, building and installation features, climate conditions, etc. We have examined a test building situated in Linköping, Sweden. By using the OPERA model, we were able to arrive at the optimal retrofit strategy, which includes a ground-coupled heat pump using electricity to run the compressor. Unfortunately, the price of electricity differs according to the time of day, month, etc. These variations are not included in the OPERA model. In OPERA, the price should be divided into 12 segments, one for each month of the year since climate data are divided in this manner. Fine tuning of a dual-fuel system (an oil-fired boiler handles the peak load and a heat pump the base thermal load) is optimized using the Mixed Integer Linear Programming (MILP) method. Adding a hot-water accumulator also makes it possible to use low electricity prices for space and domestic hot-water heating. This system competes in the model with traditional heating devices such as district heating. The optimal method of heating the building was found for using the heat pump alone.
12.	Gustavsson, Leif, et al. (author) CO2 Mitigation Costs of Large-scale Bioenergy Technologies in Competitive Electricity Markets 2003 In: Energy. - 0360-5442 .- 1873-6785. ; 28:14, s. 1405-1425 Journal article (peer-reviewed)abstract In this study, we compare and contrast the impact of recent technological developments in large biomass-fired and natural-gas-fired cogeneration and condensing plants in terms of CO2 mitigation costs and under the conditions of a competitive electricity market. The CO2 mitigation cost indicates the minimum economic incentive required (e.g. in the form of a carbon tax) to equal the cost of a less carbon extensive system with the cost of a reference system. The results show that CO2 mitigation costs are lower for biomass systems than for natural gas systems with decarbonization. However, in liberalized energy markets and given the socio-political will to implement carbon extensive energy systems, market-based policy measures are still required to make biomass and decarbonization options competitive and thus help them to penetrate the market. This cost of cogeneration plants, however, depends on the evaluation method used. If we account for the limitation of heat sinks by expanding the reference entity to include both heat and power, as is typically recommended in life-cycle analysis, then the biomass-based gasification combined cycle (BIG/CC) technology turns out to be less expensive and to exhibit lower CO2 mitigation costs than biomass-fired steam turbine plants. However, a heat credit granted to cogeneration systems that is based on avoided cost of separate heat production, puts the steam turbine technology despite its lower system efficiency at an advantage. In contrast, when a crediting method based on avoided electricity production in natural-gas-fired condensing plants is employed, the BIG/CC technology turns out to be more cost-competitive than the steam turbine technology for carbon tax levels beyond about $ 150/t C. Furthermore, steam turbine plants are able to compete with natural-gas-fired cogeneration plants at carbon tax levels higher than about $ 90/t C.
13.	Johansson, Lars, et al. (author) An open absorption system installed at a sawmill : Description of pilot plant used for timber and bio-fuel drying 2000 In: Energy. - 0360-5442 .- 1873-6785. ; 25:11, s. 1067-1079 Journal article (peer-reviewed)abstract This work describes a pilot plant and its different parts in a system used for bio-fuel drying and timber drying with an open absorption process. This technique has not been used previously in Sweden in this application. The open absorption system has been installed on four timber dryers and one bio-fuel dryer at a sawmill located in the northern part of Sweden. The annual energy demand for the dryers has decreased considerably. The specific heat demand for a conventional drying system is about 5970 kJ/kg of evaporated water. For the open absorption system, the corresponding value is a heat demand of approximately 1400 kJ/kg of evaporated water. At the same time, an additional 360 kJ/kg of electricity has to be supplied. Here, 45,000 m3 per year of dried bio-fuel has been sold on the market as a result of the decreased heat demand in the wood dryers at the sawmill. The plant has been working well and has had a high availability. The pay-off time for the investment will be approximately 3 years for nondiscounted cash-flows
14.	Jonsson, M., et al. (author) Ammonia-water bottoming cycles : a comparison between gas engines and gas diesel engines as prime movers 2001 In: Energy. - 0360-5442 .- 1873-6785. ; 26:1, s. 31-44 Journal article (peer-reviewed)abstract Ammonia-water cycles can produce more power than steam Rankine cycles in several applications. One of these applications is as a bottoming cycle to internal combustion engines. In the present study, ammonia-water bottoming cycle configurations for spark-ignition gas engines and compression-ignition gas diesel engines have been compared, Single-pressure Rankine cycles have been used as a basis for the comparison. Low heat source temperatures should increase the difference in power output between the ammonia-water cycle and the Rankine cycle. However, in this study, the results of the simulations show different trends. In most cases, the ammonia-water bottoming cycles with gas engines as prime movers generate more power compared to a Rankine cycle than when gas diesel engines are the prime movers. The temperature of the most important waste heat source, the exhaust gas, is approximately 100 degreesC higher for the gas engines than for the gas diesel engines. Therefore, for the gas engines, most of the waste heat available to a bottoming cycle is in the form of relatively high-temperature exhaust gas, while for the gas diesel engines more of the waste heat is in the form of relatively low-temperature heat sources.
15.	Mollersten, K., et al. (author) Potential and cost-effectiveness of CO2 reductions through energy measures in Swedish pulp and paper mills 2003 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 28:7, s. 691-710 Journal article (peer-reviewed)abstract Using the two criteria of potential CO2 reduction and Cost Of CO2 reduction, technical energy measures in Swedish pulp. and paper mills are investigated. Principal CO2-reducing measures analysed are: decreased specific energy utilisation, fuel switch, and CO2 capture and sequestration. Among the investigated measures, conventional technologies for electricity conservation and improved electrical conversion efficiency in existing systems for cogeneration of heat and power are identified as the most cost-effective alternatives that also have large CO2 reduction potentials. For commercially available technologies, the results indicate an accumulated reduction potential of up to 8 MtCO(2)/y (14% of the Swedish net emissions). If emerging technologies for black liquor gasification (BLG) with pre-combustion CO2 capture and sequestration are considered, the CO2 reduction potential increases by up to 6 MtCO(2)/y (10% of the Swedish net emissions). Commercialised BLG, CO2 capture and reliable CO2 sequestration technologies are identified as important potential contributors to Swedish compliance with Kyoto Protocol targets, especially in a scenario of nuclear power closure.
16.	Möllersten, Kenneth, 1966-, et al. (author) Potential and cost-effectiveness of CO2-reducing measures in the pulp and paper industry 2003 In: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 28:7, s. 691-710 Journal article (peer-reviewed)abstract Using the two criteria of potential CO2 reduction and cost of CO2 reduction, technical energy measuresin Swedish pulp and paper mills are investigated. Principal CO2-reducing measures analysed are: decreasedspecific energy utilisation, fuel switch, and CO2 capture and sequestration. Among the investigated measures, conventional technologies for electricity conservation and improved electrical conversion efficiencyin existing systems for cogeneration of heat and power are identified as the most cost-effective alternativesthat also have large CO2 reduction potentials. For commercially available technologies, the results indicatean accumulated reduction potential of up to 8 MtCO2/y (14% of the Swedish net emissions). If emergingtechnologies for black liquor gasification (BLG) with pre-combustion CO2 capture and sequestration areconsidered, the CO2 reduction potential increases by up to 6 MtCO2/y (10% of the Swedish net emissions).Commercialised BLG, CO2 capture and reliable CO2 sequestration technologies are identified as importantpotential contributors to Swedish compliance with Kyoto Protocol targets, especially in a scenario of nuclearpower closure
17.	Sundberg, Gunnel, et al. (author) Interaction effects in optimising a municipal energy system 2000 In: Energy. - 0360-5442 .- 1873-6785. ; 25:9, s. 877-891 Journal article (peer-reviewed)abstract A study is presented where factorial design is used to find how some selected economic and technical factors affect the profitability of an investment in a combined heat and power plant. The study is performed on a Swedish district heating system. The minimal cost for supplying the demanded heat is calculated with a developed energy system optimisation model, MODEST. The effects on the resulting parameters, such as system cost and optimal size of steam cycle, are calculated from a series of experiments performed using high and low levels of the most relevant factors. The conclusion of the study is that both the main factors and the interactions between them have to be analysed to establish an accurate ranking of the technical and economic factors. (C) 2000 Elsevier Science Ltd. All rights reserved.
18.	Toffolo, Andrea, et al. (author) Evolutionary algorithms for multi-objective energetic and economic optimization in thermal system design 2002 In: Energy. - 0360-5442 .- 1873-6785. ; 27:6, s. 549-567 Journal article (peer-reviewed)abstract Thermoeconomic analyses in thermal system design are always focused on the economic objective. However, knowledge of only the economic minimum may not be sufficient in the decision making process, since solutions with a higher thermodynamic efficiency, in spite of small increases in total costs, may result in much more interesting designs due to changes in energy market prices or in energy policies. This paper suggests how to perform a multi-objective optimization in order to find solutions that simultaneously satisfy exergetic and economic objectives. This corresponds to a search for the set of Pareto optimal solutions with respect to the two competing objectives. The optimization process is carried out by an evolutionary algorithm, that features a new diversity preserving mechanism using as a test case the well-known CGAM problem.
19.	Wall, Göran, 1951- (author) Thermoeconomic Optimization of a Heat Pump System 1986 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 11:10, s. 957-967 Journal article (peer-reviewed)abstract We present the application of thermoeconomics to the optimization of a single-stage heat-pump cycle. The method is well suited for application to thermodynamic processes and yields exergy losses. The marginal cost of an arbitrary variable can also be calculated. The efficiencies of the compressor, condenser, evaporator, and electric motor are chosen as decision variables which are to be optimized. Parameters such as the price of electricity and the temperature of the delivered heat may vary among optimizations, and results are presented for different parameter values.
20.	Westerlund, Lars, et al. (author) Theoretical investigation of the heat demand for public baths 1996 In: Energy. - 0360-5442 .- 1873-6785. ; 21:7-8, s. 731-737 Journal article (peer-reviewed)abstract Public baths normally use outdoor air to remove moisture from the building. This procedure results in large heating demands. A theoretical hour-based method for estimation of the heating demand has been developed. The method allows for dynamic behaviour with correct time periods for each mass-transfer level. Results of predictions with this method have been compared with yearly estimates of the heating demand based on actual measurements in a public bath. The difference is 3%. A parametric study shows that the air temperature and relative humidity in the building strongly influence the heating demand. Comparisons with other prediction methods based on use of the duration curve or mean annual outdoor temperature show differences less than 5% from results obtained with the hour-based method. The simpler approaches (use of a duration curve or mean value) fail when minimum outdoor airflow must be considered, as will be the case, for instance, when comparing different energy-saving systems or design of components for the climate system.
21.	Abdelshafy, Alaaeldin M., et al. (author) Optimized energy management strategy for grid connected double storage (pumped storage-battery) system powered by renewable energy resources 2020 In: Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-5442 .- 1873-6785. ; 192 Journal article (peer-reviewed)abstract This paper presents a grid-connected double storage system (DSS) consisting of pumped-storage hydropower (PSH) and battery. The system is supplied by photovoltaics and wind turbines. In the proposed hybrid system, batteries absorb excess renewable energy that cannot be stored in PSH and they cover loads that cannot be supplied from the water turbine. To improve the system performance, a novel energy management strategy for the DSS is proposed. The strategy is based on an optimized factor that governs the charging process of the DSS. The problem of the optimal system design is solved by a non-dominated sorting genetic algorithm (NSGA-II). The multi-objective function considers simultaneously the minimal investment cost and minimal CO2 emissions. A comparative study of photovoltaic/wind/pumped-storage hydropower and photovoltaic/wind/double storage system is performed to show the effectiveness of the proposed strategy in terms of system economic and environmental performance. The considered location of the PSH station is on Attaqa Mountain at Suez (Egypt). The results indicate the effectiveness of the proposed energy management strategy for the storage system from economic and environmental perspectives. Coupling the battery with the PSH reduces the electricity cost by 22.2% and results in minimal energy exchange with the national grid (5% of the annual demand). A sensitivity analysis shows the largest variation of the electricity cost with changing the capital cost of the solar and wind generators. Also, it is observed that when the load increases, the optimal size of the system components increases, but it isn't proportional with the demand increase as could be expected. (C) 2019 Elsevier Ltd. All rights reserved.
22.	Adom, Philip Kofi (author) Business cycle and economic-wide energy intensity: The implications for energy conservation policy in Algeria 2015 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 88, s. 334-350 Journal article (peer-reviewed)abstract Despite the prevalence of voluntary and involuntary energy conservation policies, developing countries in Africa continue to struggle to achieve energy efficiency targets. Consequently, energy intensity levels have risen threatening the security of the energy system. This raises the important question: is there an economic state that induces agents to be energy conscious? In this study, we study the case of Algeria's energy intensity from 1971 to 2010. First, the paper argues that there is a certain economic state that economic agents find investing in energy conservation a viable option. Any state different from that would mean not investing in energy conservation. Second, the paper argues that the economy can do better even with an infinitesimal reduction in fuel subsidy, and that the gains in revenue from the policy can compensate for the negative socio-economic and equity impacts associated with such a policy. Third, the paper argues that, so long as, industrial expansion in the country move parallel with investment in technological innovation, long-term sustainable growth and energy conservation targets are jointly feasible. Fourth, the paper shows that income elasticity evolves with the business cycle, and the absorptive capability of the host country affects how FDI (foreign direct inflows) impact energy intensity. (C) 2015 Elsevier Ltd. All rights reserved.
23.	Adom, Philip Kofi (author) Determinants of energy intensity in South Africa: Testing for structural effects in parameters 2015 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 89, s. 334-346 Journal article (peer-reviewed)abstract A cursory look at South Africa's energy data reveals that, energy intensity has consistently declined for the past two decades. The logical question that ensues is; what might have contributed to this phenomenon? The current study aims to investigate how different phenomena have contributed to the decline in South Africa's energy intensity. The study also tests for structural effects in the model parameters. The result showed that the de-industrialisation since 1980 and the changes in trade structure in favour of more imports have contributed significantly to the decline in energy intensity, in South Africa. Also, the current industry composition has induced technological transfer via FDI (Foreign direct inflows) and this has contributed to the decline in energy intensity levels, in South Africa. The individual effect analyses showed that each of the predictors shared significant amount of variance with the regression effect. Finally, there are significant structural effects in the parameters, and this has rendered the effects of regressors asymmetric. (C) 2015 Elsevier Ltd. All rights reserved.
24.	Ahmad, Waqar, et al. (author) Benzene conversion using a partial combustion approach in a packed bed reactor 2022 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 239:Part C Journal article (peer-reviewed)abstract This study investigates the partial combustion technique for tar conversion using a modified experimental set up comprising a packed bed reactor with bed-inside probe for air supply. Simulated producer gas (SPG) and benzene were selected as a real producer gas alternative and model tar component respectively. The benzene conversion was investigated under different experimental conditions such as reactor temperature (650–900 °C), packed bed height (0–12 cm), residence time (1.2–1.9 s), air fuel ratio (0.2 and 0.3) and SPG composition. The results showed insignificant effect of temperature over benzene conversion while air fuel ratio of 0.3 caused high benzene conversion than at 0.2. Absence of packed bed lead high benzene conversion of 90% to polyaromatic hydrocarbons (PAHs) compared to similar low PAHs free benzene conversion of 32% achieved at both packed heights. In SPG composition effect, H2 and CH4 had a substantial inverse effect on benzene conversion. An increase in H2 concentration from 12 to 24 vol% increased the benzene conversion from 26 to 45% while an increase in CH4 concentration from 7 to 14 vol% reduced the benzene conversion from 28 to 4%. However, other SPG components had insignificant impacts on benzene conversion.
25.	Aichmayer, Lukas, et al. (author) Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator 2018 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 159, s. 184-195 Journal article (peer-reviewed)abstract This work presents the experimental evaluation of a novel pressurized high-temperature solar air receiver for the integration into a micro gas-turbine solar dish system reaching an air outlet temperature of 800°C. The experiments are conducted in the controlled environment of the KTH high-flux solar simulator with well-defined radiative boundary conditions. Special focus is placed on providing detailed information to enable the validation of numerical models. The solar receiver performance is evaluated for a range of operating points and monitored using multiple point measurements. The porous absorber front surface temperature is measured continuously as it is one of the most critical components for the receiver performance and model validation. Additionally, pyrometer line measurements of the absorber and glass window are taken for each operating point. The experiments highlight the feasibility of volumetric solar receivers for micro gas-turbine based solar dish systems and no major hurdles were found. A receiver efficiency of 84.8% was reached for an air outlet temperature of 749°C. When using a lower mass flow, an air outlet temperature of 800°C is achieved with a receiver efficiency of 69.3%. At the same time, all material temperatures remain below permissible limits and no deterioration of the porous absorber is found.
26.	Aichmayer, Lukas, et al. (author) Thermo-mechanical solar receiver design and validation for a micro gas-turbine based solar dish system 2020 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 196 Journal article (peer-reviewed)abstract This work presents the comprehensive development of a solar receiver for the integration into a micro gas-turbine solar dish system. Special focus is placed on the thermo-mechanical design to ensure the structural integrity of all receiver components for a wide range of operating conditions. For the development, a 3-dimensional coupled multi-physics model is established and is validated using experimental data. Contrary to previous studies, the temperature of the irradiated front surface of the absorber is included in the comprehensive validation process which results in a high level of confidence in the receiver design.Finally, a full-scale solar receiver for the integration into the OMSoP solar dish system is designed and its performance determined for a wide operating range to define its safe operating envelope using the validated model. It is shown that the receiver is capable of operating at 803_C with an efficiency of 82.1% and a pressure drop of 0.3% at the nominal operating point, while at the same time functioning effectively for a wide range of off-design conditions without compromising its structural integrity. At the nominal operating point, the maximum comparison stress of the porous absorber is 5.6 MPa compared to a permissible limit of 7.4 MPa.
27.	Alirahmi, Seyed Mojtaba, et al. (author) An innovative four-objective dragonfly-inspired optimization algorithm for an efficient, green, and cost-effective waste heat recovery from SOFC 2023 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 263 Journal article (peer-reviewed)abstract This work proposes a novel yet practical dragonfly optimization algorithm that addresses four competing ob-jectives simultaneously. The proposed algorithm is applied to a hybrid system driven by the solid oxide fuel cell (SOFC) integrated with waste heat recovery units. A function-fitting neural network is developed to combine the thermodynamic model of the system with the dragonfly algorithm to mitigate the calculation time. According to the optimization outcomes, the optimum parameters create significantly more power and have a greater exergy efficiency and reduced product costs and CO2 emissions compared to the design condition. The sensitivity analysis reveals that while the turbine inlet temperatures of power cycles are ineffective, the fuel utilization factor and the current density significantly impact performance indicators. The scatter distribution indicates that the fuel cell temperature and steam-to-carbon ratio should be kept at their lowest bound. The Sankey graph shows that the fuel cell and afterburner are the main sources of irreversibility. According to the chord diagram, the SOFC unit with a cost rate of 13.2 $/h accounts for more than 29% of the overall cost. Finally, under ideal conditions, the flue gas condensation process produces an additional 94.22 kW of power and 760,056 L/day of drinkable water.
28.	Anglart, Henryk, 1954-, et al. (author) Mechanistic modelling of dryout and post-dryout heat transfer 2018 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 161, s. 352-360 Journal article (peer-reviewed)abstract In this paper a new mechanistic model for the diabatic annular two-phase flow is presented and applied to prediction of dryout and post-dryout heat transfer in various channels. The model employs a computational fluid dynamics code - OpenFOAM (R) - to solve the governing equations of two-phase mixture flowing in a heated channel. Additional closure laws have been implemented to calculate the location of the dryout and to predict wall temperature in the post-dryout region. Calculated results have been compared with experimental data obtained in pipes and good agreement between predictions and measurements has been achieved. The presented model is applicable to complex geometries and thus can be used for prediction of post-dryout heat transfer in a wide variety of energy conversion systems.
29.	Anjo, J., et al. (author) Modeling the long-term impact of demand response in energy planning : The Portuguese electric system case study 2018 In: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 165, s. 456-468 Journal article (peer-reviewed)abstract With the urge to decrease carbon emissions, electricity systems need to evolve to promote the integration of renewable resources and end-use energy efficiency. Demand Response (DR) can be used as a strategy, one among many, to improve the balance between demand and supply of electricity, especially in systems that rely heavily on variable energy renewable resources. Thus, it is important to understand up to what extent a countrywide system would cope with DR implementation. In this work, the impact of demand response in the long-term is assessed, using a model of the Portuguese electricity system in the modeling tool OSeMOSYS. The theoretical potential of DR is computed to understand better the impact on the overall system planning, by analyzing three scenarios – a business as usual scenario, a carbon-free system scenario in 2050, and a scenario without heavy carbon emission restrictions. DR impact in all three scenarios results in a decrease in the overall costs, on the capacity installed and in an increase in the percentage of renewable capacity. Further, an economic analysis showed that DR would take 15 years, on average, to influence the average electricity cost and that the reduction in total costs is mainly due to the avoided capacity investments.
30.	Arnaudo, Monica, et al. (author) Heat demand peak shaving in urban integrated energy systems by demand side management - A techno-economic and environmental approach 2019 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 186 Journal article (peer-reviewed)abstract The integration of variable renewable resources and decentralized energy technologies generates the need for a larger flexibility of the energy demand. In order to fully deploy a demand side management approach, synergies between interconnected energy systems have to be systematically implemented. By taking this standpoint, this study proposes a new approach to explore the potential of multi-energy integrated energy systems. This approach is constituted by two main steps, which are (1) the performance simulation of selected energy infrastructures and (2) the estimation of related techno-economic performance indicators. Step (1) expands the work presented in previous literature, by including a novel co-simulation feature. In step (2), the levelized cost of energy and location-dependent emission factors are used as key performance indicators. In this paper, the presented approach is demonstrated by implementing two demand side management options for heat peak demand shaving. A Swedish residential neighborhood is considered as a case study. The first option explores the potential of storing heat in the thermal mass of residential buildings. The proposed strategies lead to a decrease of up to 70% of primary energy consumption, depending on the indoor comfort requirements. The second option estimates the techno-economic feasibility of a new set of scenarios based on the integration of geothermal distributed heat pumps within a district heating network. The district heating scenario is found to be the most techno-economical convenient. Nevertheless, a moderate penetration of distributed heat pumps (around 20%) is shown to have a good trade-off with the reduction of CO2 emissions.
31.	Arnaudo, Monica, et al. (author) Techno-economic analysis of demand side flexibility to enable the integration of distributed heat pumps within a Swedish neighborhood 2020 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 195 Journal article (peer-reviewed)abstract The energy infrastructure in Stockholm faces an imminent problem caused by the saturation of the electricity distribution grid capacity. Given promising economic savings, a few city neighborhoods have decided to switch from district heating to domestic heat pumps. Thus, technical concerns arise. This study aims at proposing demand side management solutions to unlock the integration of distributed heat pumps. A techno-economic analysis is presented to assess the potential of using the buildings’ thermal mass as energy storage. By means of co-simulation, the electricity grid and the buildings are coupled through a feedback control. The grid capacity is monitored to avoid overloadings. The indoor temperature is controlled in order to serve as thermal energy storage. It is found that, given the grid's capacity limits, the infrastructure should still be partly connected to the district heating (around 7% of the heat demand). This dependency decreases of around 1% when the buildings’ thermal mass is used as thermal storage, with a range of ±0.5 °C. On a heat pump level, the disconnections decrease up to 50%, depending on the buildings’ thermal mass capacity. Thus better techno-economic (about −2% on the levelized cost) and environmental (about −1% on the CO2 emissions) performances are unlocked.
32.	Arnaudo, Monica, et al. (author) Waste heat recovery in low temperature networks versus domesticheat pumps - A techno-economic and environmental analysis 2021 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 219 Journal article (peer-reviewed)abstract The planning of energy infrastructures in new districts often follows the practice adopted for the rest of the city. In Stockholm, district heating is a common solution for multi-apartment neighborhoods. Recently, because of an average clean electricity mix, heat pumps have gained interest. However, European studies suggest to limit the reliance on electrification to avoid an extreme demand increase. Thus, an effort is required to improve the environmental impact of alternative options. This study proposes waste heat recovery in low temperature networks as a promising solution. By means of a techno-economic and environmental analysis, this option is compared to domestic heat pumps. A new approach is proposed to combine a district level perspective with simulation tools able to capture sector-coupling interactions. Scenarios, for a real neighborhood, assess waste heat recovery potential and electricity grid loading status. Results show that a waste heat recovery capacity equal to 10% of the peak load can reduce fossil fuel use of 40%. Local grid limitations are shown to be a bottleneck for the feasibility of domestic heat pumps. Their heat generation cost is 28% higher than for district heating. The carbon footprint is strongly dependent on the emission factor of the electricity mix (+11%/-24%).
33.	Averfalk, Helge, 1988-, et al. (author) Economic benefits of fourth generation district heating 2020 In: Energy. - London, UK : Elsevier. - 0360-5442 .- 1873-6785. ; 193 Journal article (peer-reviewed)abstract The main impetus for lower distribution temperatures in district heating systems is the lower heat supply costs obtained by these lower temperatures. In this paper, the differences in heat supply costs for two different temperature levels have been estimated for various future heat supply options. The estimations were obtained by modelling a district heating system characterised by typical climate conditions for Central Europe. High sensitivity to lower supply costs from lower temperatures was found for geothermal heat, industrial excess heat, and heat pumps, whereas low cost sensitivity was estimated for combined heat and power plants using waste or biomass. Lower heat distribution loss constitutes a minor component of the total cost reductions. The current use of high heat distribution temperatures was identified as an important barrier for the transition to renewable and recycled heat supply in district heating systems. Hence, lower distribution temperatures would facilitate this required transition because lower distribution temperatures provide higher profitability for these renewable and recycled heat sources. © 2019 The Authors. Published by Elsevier Ltd.
34.	Averfalk, Helge, 1988-, et al. (author) Novel low temperature heat distribution technology 2018 In: Energy. - London : Elsevier. - 0360-5442 .- 1873-6785. ; 145, s. 526-539 Journal article (peer-reviewed)abstract Lower future heat demands and lower availability of non-fossil high temperature heat supply are expected future market conditions that restrain the long-term viability of contemporary district heating systems. Hence, current district heating technology should be enhanced to increase system performance in new heat distribution areas. This paper aims to outline a proposal for technical improvements required to achieve lower annual average return temperatures in new residential buildings to improve viability in future market conditions. The proposed technical solution consists of three principle changes: three-pipe distribution networks, apartment substations, and longer thermal lengths for heat exchangers. The three technical modifications aims at addressing system embedded temperature errors. Furthermore, a simulation model was developed to assess the proposed technical solution concerning different energy performances of buildings and different thermal lengths in heat exchangers. The results show that implementation of the three technical modifications reaches time-weighted annual average return temperatures of 17–21 °C with supply temperatures of about 50 °C. The results also verify the increased necessity to separate the network return flows into delivery and recirculation flows in residential substations as energy performance in buildings increase.
35.	Ayele, Getnet Tadesse, et al. (author) Optimal placement and sizing of heat pumps and heat only boilers in a coupled electricity and heating networks 2019 In: Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-5442 .- 1873-6785. ; 182, s. 122-134 Journal article (peer-reviewed)abstract Multi-energy systems are reported to have a better environmental and economic performance relative to the conventional, single-carrier, energy systems. Electrification of district heating networks using heat pumps and combined heat and power technologies is one such example. Due to lack of suitable modelling tools, however, the sizing and optimal placement of heat pumps is always done only from the heating network point of view which sometimes compromises the electricity network. This paper proposes an integrated optimization algorithm to overcome such limitation. A load flow model based on an extended energy hub approach is combined with a nested particle swarm optimization algorithm. A waste to energy combined heat and power plant, heat pumps (HPs), heat only boiler (HOB), solar photovoltaic, wind turbines and imports from the neighborhood grids are considered in the case studies. The results show that optimal placement and sizing of HPs and a HOB using the proposed methodology avoids an unacceptable voltage profiles and overloading of the electricity distribution network, which could arise while optimizing only from the heating network point of view. It also shows that up to 41.2% of the electric loss and 5% of the overall operating cost could be saved.
36.	Badenes, Borja, et al. (author) Development of advanced materials guided by numerical simulations to improve performance and cost-efficiency of borehole heat exchangers (BHEs) 2020 In: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 201 Journal article (peer-reviewed)abstract One promising way to improve the efficiency of borehole heat exchangers (BHEs) in shallow geothermal applications is to enhance the thermal properties of the materials involved in its construction. Early attempts, such as using metal tubes in the 1980s or the utilization of thin–foil hoses, did not succeed in being adopted by the market for diverse reasons (cost, corrosion, fragility, etc…). In parallel, the optimization of pipe size, the use of double-U-tubes, thermally enhanced grout, etc. were able to bring the measure for the BHE efficiency, the borehole thermal resistance, from 0.20 to 0.15 K/(Wm) down to 0.08–0.06 K/(Wm) in the best solutions today. A further improvement cannot be expected without development of new, dedicated materials, combining the versatility of plastic like PE with an increased thermal conductivity that matches the respective properties of the rock and soil. This goal was included in the Strategic Research and Innovation Agenda of the European Technology Platform on Renewable Heating and Cooling in 2013. Within an EU supported project, both BHE pipes and grouting materials have been produced prototypically in small amounts, suitable for the first tests in the intended environment. The present work explains the research pathways envisaged and the resulting sensitivity analysis to highlight the influence of some of the most critical parameters that affect the overall performance of a GSHP system. The results have allowed guiding the real development of more efficient new advanced materials for different scenarios representative of different European regions. Finally the developed materials and their properties are discussed, including a comparative assessment about their compliance with reference material properties as currently seen in the BHE market. © 2020 The Author(s)
37.	Bagge, Hans, et al. (author) Measurements of household electricity and domestic hot water use in dwellings and the effect of different monitoring time resolution 2011 In: Energy. - : Elsevier BV. - 1873-6785 .- 0360-5442. ; 36:5, s. 2943-2951 Journal article (peer-reviewed)abstract The use of household electricity and domestic hot water has been measured for 72 apartments in an apartment building located in the south of Sweden. The measurements were carried out with samples every 6 s, a tenfold increase in resolution compared to available published data, during a measurement period of five days, in the winter season, including a weekend. The influence of the time resolution on the distribution of data was analysed by integrating the 6 s data to represent longer logging intervals. Extreme values, especially the high values, are shown to be reduced if the time interval is increased. The maximum household electric power was 50% higher at a 6 s resolution compared to 60 s and the corresponding difference for domestic hot water flow was 40%. Daily variations has to be considered for photovoltaic installations and solar thermal collectors, energy simulations of buildings need at least hourly data and all kind of power design in a building or its services benefits from much more resolved data. (C) 2011 Elsevier Ltd. All rights reserved.
38.	Bahaj, AbuBakr S., et al. (author) Shaping array design of marine current energy converters through scaled experimental analysis 2013 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 59:0, s. 83-94 Journal article (peer-reviewed)abstract Marine current energy converters or tidal turbines represent an emerging renewable energy technology that can provide a predictable supply of electricity. Single devices are in operation around the world with aspirations to deploy farms or arrays of multiple devices. We present an experimental study that has characterised the downstream wake flow around a 1/15th-scale turbine in a large circulating water channel and a series of experiments involving static actuator disks at 1/120th-scale allowing simulation of multiple-device layouts. Our analysis demonstrates that the near wake is highly turbulent with structures generated by the rotor and support structure. This region of flow may prove difficult to numerically simulate with a high degree of accuracy. In the far wake the performance of static actuator disks can be matched to mechanical rotors reducing scale and cost facilitating replication of complex array geometries. Here the ambient turbulence and geometric properties of the device/channel drive the wake recovery towards free stream conditions. Devices operating downstream of others will be subject to a non-steady flow field making comparative performance difficult. We discuss the possibility of unequal device specification and rated power within an array (unlike wind farms) providing a more representative measure of array performance.
39.	Baigmohammadi, Mohammadreza, et al. (author) Experimental study on the effects of mixture flow rate, equivalence ratio, oxygen enhancement, and geometrical parameters on propane air premixed flame dynamics in non-adiabatic meso-scale reactors 2017 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 121, s. 657-675 Journal article (peer-reviewed)abstract In the present study, the effects of reactive mixture flow rate, adding oxygen to propane-air mixture, geometrical parameters, and equivalence ratio on propane-air/oxygen premixed flame dynamics in non adiabatic meso-scale reactors were experimentally investigated. During the experiments, seven flame regimes of blow-off, blow-out, asymmetric stationary, stationary-repetitive extinction and re-ignition (RERI), forced/self-RERI, RERI-flash-back, and flash-back were observed. The results showed that increasing the reactive mixture flow rate could generally promote variety of the flame regimes and also improve flame stability in the non-adiabatic meso-scale reactors, especially in 40% and 80% oxygen enhanced cases. Also, the results demonstrated that increasing the reactor inner diameter and equivalence ratio generally extended propane-air- oxygen flame stability and its presence range in the non adiabatic meso-scale reactors. Moreover, it was shown that increasing the reactor length and also increasing the added oxygen to propane-air mixture more than 40% promoted flame instability and consequently restricted propane-air-oxygen flame presence range in the non-adiabatic meso-scale reactors. Also, it was shown that variations in the mixture flow rate, the reactor length and inner diameter, equivalence ratio, and oxygen concentration in propane-air mixture could significantly influence the flame average propagation speed, acoustic, and chemiluminescence in the non-adiabatic meso-scale reactors.
40.	Balderrama, Sergio, et al. (author) Surrogate models for rural energy planning : Application to Bolivian lowlands isolated communities 2021 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 232 Journal article (peer-reviewed)abstract Thanks to their modularity and their capacity to adapt to different contexts, hybrid microgrids are a promising solution to decrease greenhouse gas emissions worldwide. To properly assess their impact in different settings at country or cross-country level, microgrids must be designed for each particular situation, which leads to computationally intractable problems. To tackle this issue, a methodology is proposed to create surrogate models using machine learning techniques and a database of microgrids. The selected regression model is based on Gaussian Processes and allows to drastically decrease the computation time relative to the optimal deployment of the technology. The results indicate that the proposed methodology can accurately predict key optimization variables for the design of the microgrid system. The regression models are especially well suited to estimate the net present cost and the levelized cost of electricity (R-2 = 0.99 and 0.98). Their accuracy is lower when predicting internal system variables such as installed capacities of PV and batteries (R-2 = 0.92 and 0.86). A least-cost path towards 100% electrification coverage for the Bolivian lowlands mid-size communities is finally computed, demonstrating the usability and computational efficiency of the proposed framework.
41.	Bauer, N., et al. (author) Assessing global fossil fuel availability in a scenario framework 2016 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 111, s. 580-592 Journal article (peer-reviewed)abstract This study assesses global, long-term economic availability of coal, oil and gas within the Shared Socio-economic Pathway (SSP) scenario framework considering alternative assumptions as to highly uncertain future developments of technology, policy and the economy. Diverse sets of trajectories are formulated varying the challenges to mitigation and adaptation of climate change. The potential CO2 emissions from fossil fuels make it a crucial element subject to deep uncertainties. The analysis is based on a well-established dataset of cost-quantity combinations that assumes favorable techno-economic developments, but ignores additional constraints on the extraction sector. This study significantly extends the analysis by specifying alternative assumptions for the fossil fuel sector consistent with the SSP scenario families and applying these filters (mark-ups and scaling factors) to the original dataset, thus resulting in alternative cumulative fossil fuel availability curves. In a Middle-of-the-Road scenario, low cost fossil fuels embody carbon consistent with a RCP6.0 emission profile, if all the CO2 were emitted freely during the 21st century. In scenarios with high challenges to mitigation, the assumed embodied carbon in low-cost fossil fuels can trigger a RCP8.5 scenario; low mitigation challenges scenarios are still consistent with a RCP4.5 scenario.
42.	Behi, Mohammadreza, et al. (author) Evaluation of a novel solar driven sorption cooling/heating system integrated with PCM storage compartment 2018 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 164, s. 449-464 Journal article (peer-reviewed)abstract Recently the interest in solar thermal cooling has been growing for Air Conditioning (AC) applications. This paper presents an applied experimental and numerical evaluation of a novel triple-state sorption solar cooling module. The performance of a LiCl-H2O based sorption module (SM) for cooling/heating system with integration of an external energy storage has been evaluated. The dynamic behavior of the SM, which can be driven by solar energy, is presented. Two PCM assisted configurations of the SM have been studied herein; (i) PCM assisted sorption module for cooling applications (ii) PCM assisted sorption module for heating applications. Initially, an experimental investigation was carried out to evaluate the charging/discharging process of the SM without external energy storage. Secondly, the initial experimental configuration was modeled with a PCM integrated storage compartment. The PCM storage compartment was connected to the Condenser/Evaporator (C/E) of the SM. The temporal history of the sorption module's C/E and PCM storage, the cyclic and average performance in terms of cooling/heating capacity, cooling/heating COP, and the total efficiency were experimentally and numerically investigated. Furthermore, PCM charging/discharging power rate and solidification/melting process of the PCM in the integrated storage compartment to the SM were predicted by the model.
43.	Behi, Mohammadreza, et al. (author) Experimental and numerical investigation on hydrothermal performance of nanofluids in micro-tubes 2020 In: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 193 Journal article (peer-reviewed)abstract Nanoscale solid particles suspended in a base liquid are a new class of nano-engineered colloidal suspension, defined with a coined name of nanofluids (NFs). The effect of dispersing nanoparticles (NPs) on the hydraulic and thermal (hydrothermal) performance of the conventional coolants is a matter of importance in many applications. This work experimentally and numerically presents the effect of different parameters, including the concentration and size of the NPs, on two primary parameters, namely heat transfer coefficient and friction factor in a microtube. The numerical modeling of colloidal suspensions was conducted based on single-phase as well as Eulerian-Mixture two-phase approaches and showed a good agreement with experimental results. The numerical results displayed that the suspended NPs remarkably increased the convective heat transfer coefficient as well as friction factor by as much as 42% and 22% (in NP concentration range of 1%–9%, and NP size range of 13–130 nm and Reynolds number of 400) respectively. Besides, two new correlations were developed based on the results obtained from experimentally validated models to predict the hydrothermal response of NFs in the laminar regime. Moreover, correlations were successfully created to predict the Nusselt number and friction factor of nanofluids, with ±8% and ±5% agreement between numerical data and predictions, respectively.
44.	Bian, Xiaolei, et al. (author) A model for state-of-health estimation of lithium ion batteries based on charging profiles 2019 In: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 177, s. 57-65 Journal article (peer-reviewed)abstract Using an equivalent circuit model to characterize the constant-current part of a charging/discharging profile, a model is developed to estimate the state-of-health of lithium ion batteries. The model is an incremental capacity analysis-based model, which applies a capacity model to define the dependence of the state of charge on the open circuit voltage as the battery ages. It can be learning-free, with the parameters subject to certain constraints, and is able to give efficient and reliable estimates of the state-of-health for various lithium ion batteries at any aging status. When applied to a fresh LiFePO 4 cell, the state-of-health estimated by this model (learning-unrequired or learning-required)shows a close correspondence to the available measured data, with an absolute difference of 0.31% or 0.12% at most, even for significant temperature fluctuation. In addition, NASA battery datasets are employed to demonstrate the versatility and applicability of the model to different chemistries and cell designs.
45.	Blarke, Morten B, et al. (author) Intermittency-friendly and high-efficiency cogeneration : Operational optimisation of cogeneration with compression heat pump, flue gas heat recovery, and intermediate cold storage 2011 In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 36:12, s. 6867-6878 Journal article (peer-reviewed)abstract This paper develops, implements, and applies a mathematical model for economic unit dispatch for a novel cogeneration concept (CHP-HP-FG-CS (CHP with compression heat pump and cold storage using flue gas heat)) that increases the plant's operational flexibility. The CHP-HP-FG-CS concept is a high-efficiency and widely applicable option in distributed cogeneration better supporting the co-existence between cogenerators and intermittent renewables in the energy system. The concept involves integrating an efficient high-temperature compression heat pump that uses only waste heat recovered from flue gases as low-temperature heat source, and an intermediate cold thermal storage allowing for non-concurrent operation of the cogeneration unit and the heat pump unit. The model is applied for a paradigmatic case study that shows how the integration of a heat pump affects the operational strategy of a cogeneration plant. It is found that CHP-HP-FG-CS offers significant reductions in fuel consumption (-8.9%) and operational production costs (-11.4%). The plant's fuel-to-energy efficiency increases from 88.9 to 95.5%, which is state-of-the-art. The plant's intermittency-friendliness coefficient Rc improves only marginally due to the constrained nature of the low-temperature heat source and the associated small capacity of the heat pump unit. Significant improvements in Rc are found when increasing the heat pump capacity assuming the availability of an unconstrained heat source
46.	Bozzi, Silvia, et al. (author) Wave energy farm design in real wave climates : the Italian offshore 2017 In: Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-5442 .- 1873-6785. ; 122, s. 378-389 Journal article (peer-reviewed)abstract The work focuses on hydrodynamic interactions between heaving wave energy converters (WEC). Wave parks of four devices are simulated in the time domain by a hydrodynamic-electromagnetic model, coupled with a boundary element code for the estimation of hydrodynamic parameters. Different layouts (linear, square and rhombus), WEC separation distances (5, 10, 20 and 30 buoy diameters) and incident wave directions (30 degrees apart) are considered to assess the effect of design parameters on array power production. Then, a site-specific design optimization is carried out for different Italian locations and some key insights on wave farm design in real wave climates are provided. The results show that the effect of wave interactions on energy absorption is not expected to be a main issue, as long as the devices are separated by at least 10 buoy diameters and that the layouts are oriented to achieve the maximum energy absorption for the prevailing wave direction.
47.	Bundschuh, Jochen, et al. (author) Algae-biomass for fuel, electricity and agriculture 2014 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 78, s. 1-3 Journal article (peer-reviewed)
48.	Börjesson, Martin, 1980, et al. (author) Bioenergy futures in Sweden - Modeling integration scenarios for biofuel production 2016 In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 109, s. 1026-1039 Journal article (peer-reviewed)abstract Use of bioenergy can contribute to greenhouse gas emission reductions and increased energy security. However, even though biomass is a renewable resource, the potential is limited, and efficient use of available biomass resources will become increasingly important. This paper aims to explore system interactions related to future bioenergy utilization and cost-efficient bioenergy technology choices under stringent CO2 constraints. In particular, the study investigates system effects linked to integration of advanced biofuel production with district heating and industry under different developments in the electricity sector and biomass supply system. The study is based on analysis with the MARKAL_Sweden model, which is a bottom-up, cost-optimization model covering the Swedish energy system. A time horizon to 2050 is applied. The results suggest that system integration of biofuel production has noteworthy effects on the overall system level, improves system cost-efficiency and influences parameters such as biomass price, marginal CO2 emission reduction costs and cost-efficient biofuel choices in the transport sector. In the long run and under stringent CO2 constraints, system integration of biofuel production has, however, low impact on total bioenergy use, which is largely decided by supply-related constraints, and on total transport biofuel use, which to large extent is driven by demand.
49.	Börjesson, Pål, et al. (author) Regional Production and Utilization of Biomass in Sweden 1996 In: Energy. - 0360-5442 .- 1873-6785. ; 21:9, s. 747-764 Journal article (peer-reviewed)
50.	Canales, Fausto A., et al. (author) Assessing temporal complementarity between three variable energy sources through correlation and compromise programming 2020 In: Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-5442 .- 1873-6785. ; 192 Journal article (peer-reviewed)abstract Renewable energies are deployed worldwide to mitigate climate change and push power systems towards sustainability. Nevertheless, the weather-dependent nature and variability of renewable energy sources often hinders their integration to national grids. The combination of different sources to profit from their beneficial complementarity has often been proposed as a partial solution to overcome these issues. This paper introduces a novel method for quantifying total temporal energetic complementarity between three different variable renewable sources, based on well-known mathematical techniques: correlation coefficients and compromise programming. It has the major advantage of allowing the simultaneous assessment of partial and total complementarity, as well as allowing for a linear assessment of complementarity. The method is employed to study the complementarity of wind, solar and hydropower generation on different temporal scales in a region of Poland. Results show that timescale selection has a determinant impact on the estimated value of the total temporal complementarity index. (C) 2019 Elsevier Ltd. All rights reserved.

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