| 1. |
- Gustafsson, Stig-Inge
(författare)
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Load management in municipal electricity systems
- 1997
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Ingår i: International Journal of Energy Research. - : John Wiley & Sons. - 0363-907X .- 1099-114X. ; 21:9, s. 787-791
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Tidskriftsartikel (refereegranskat)abstract
- Load management is one means of reducing maximum electricity load, and hence also the cost of electricity. In Sweden, the amount charged during the maximum load hour might be about 200 times higher than the standard charge for one kilowatt-hour. If the load could be reduced by certain equipment in factories and buildings, the need for new power stations and higher capacity in the grid would also be decreased. Using electricity load data for one full year and a short computer program, this paper shows by how much the load could be reduced by postponing demand. If part of the load could be postponed by only one hour, this part may need to be only very small for maximum benefit. If longer time segments were practicable, larger chunks could be transferred. The main result of the study is, however, that load management in practice is a very subtle task if an optimal solution is to be achieved
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| 2. |
- Gustafsson, Stig-Inge
(författare)
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Load management measures in a carpentry factory
- 1998
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Ingår i: International Journal of Energy Research. - : John Wiley & Sons. - 0363-907X .- 1099-114X. ; 22:14, s. 1267-1274
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Tidskriftsartikel (refereegranskat)abstract
- The wood manufacturing industry in Sweden is not very often the subject of academic research activities. In certain parts of Sweden, generally in rural areas, this industrial branch is of major importance as a local employer. If the companies could grow and prosper it would lead to a more vivid countryside and decrease migration to larger towns and cities. The council of the European Community has therefore introduced certain funds for research projects in such rural areas. This paper describes the use of electricity and heat in a carpentry factory. The result shows that energy conservation measures and load management might be of significant importance in order to make the company more profitable. Even small savings can be the difference between survival or bankruptcy. For the studied factory it is obvious that much equipment for heating purposes are in a poor state. The steam system which could be useful for decreasing the use of electricity heating suffers from leaking steam traps and other imperfections which lead to severe losses in both kilowatt-hours and money. The steam system is therefore not used in an optimal way
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| 3. |
- Mattsson, Niclas, 1967, et al.
(författare)
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Assessing New Energy Technologies Using an Energy System Model with Endogenized Experience Curves
- 1997
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Ingår i: International Journal of Energy Research. - 1099-114X .- 0363-907X. ; 21, s. 385-393
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Tidskriftsartikel (refereegranskat)abstract
- Most energy systems models treat reductions of technology investment costs exogenously. In these models, investments may be postponed until the costs become low. This model behaviour is unreasonable, since early investments are necessary to realize the cost reductions, a phenomenon known as the experience effect. We have developed a global energy systems model with endogenized experience curves, and have conducted a pilot study to demonstrate the new insights which can be obtained with the model. In this initial application, we study the emergence of new energy technologies such as photovoltaics and fuel cells, competition between technologies and technology lock‐in effects
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| 4. |
- Zhu, Bin
(författare)
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Applications of hydrofluoride ceramic membranes for advanced fuel cell technology
- 2000
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Ingår i: International Journal of Energy Research. - 0363-907X .- 1099-114X. ; 24:1, s. 39-49
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Tidskriftsartikel (refereegranskat)abstract
- New types of materials, hydrofluoride-alumina ceramic composites containing one hydride component, CaH2, have been studied for fuel cell applications. Excellent fuel cell performances were achieved for a peak power density of 180 mW cm(-2) at 300 mA cm(-2), and a short-circuit current density near 1000 mA cm(-2). In fuel cell measurements the conductivity and ionic transport properties of the hydrofluoride-based electrolytes have also been investigated. During fuel cell operation, water was often observed at the cathode (air side), indicating that proton conduction occurs in these electrolyte materials. The experiments show an interesting chance for the future development of innovative fuel cell technology for commercialization.
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| 5. |
- Abbas, Ghazanfar, et al.
(författare)
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Electrochemical study of nanostructured electrode for low-temperature solid oxide fuel cell (LTSOFC)
- 2014
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 38:4, s. 518-523
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Tidskriftsartikel (refereegranskat)abstract
- Zn-based nanostructured Ba0.05Cu0.25Fe0.10Zn0.60O (BCFZ) oxide electrode material was synthesized by solid-state reaction for low-temperature solid oxide fuel cell. The cell was fabricated by sandwiching NK-CDC electrolyte between BCFZ electrodes by dry press technique, and its performance was assessed. The maximum power density of 741.87 mW-cm(-2) was achieved at 550 degrees C. The crystal structure and morphology were characterized by X-ray diffractometer (XRD) and SEM. The particle size was calculated to be 25 nm applying Scherer's formula from XRD data. Electronic conductivities were measured with the four-probe DC method under hydrogen and air atmosphere. AC Electrochemical Impedance Spectroscopy of the BCFZ oxide electrode was also measured in hydrogen atmosphere at 450 degrees C.
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| 6. |
- Ahlström, Johan, 1990, et al.
(författare)
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Bark as feedstock for dual fluidized bed gasifiers. Operability, efficiency, and economics
- 2019
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 43:3, s. 1171-1190
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Tidskriftsartikel (refereegranskat)abstract
- The demand for biofuels and biochemicals is expected to increase in the future, which will in turn increase the demand for biomass feedstock. Large gasification plants fueled with biomass feedstock are likely to be a key enabling technology in a resource-efficient, bio-based economy. Furthermore, the costs for producing biofuels and biochemicals in such plants could potentially be decreased by utilizing inexpensive low-grade residual biomass as feedstock. This study investigates the usage of shredded tree bark as a feedstock for the production of biomethane in the GoBiGas demonstration plant in Gothenburg, Sweden, based on a 32 MWth industrial dual fluidized bed gasification unit. The plant was operated with bark feedstock for 12 000 hours during the period 2014 to 2018. Data from the measurement campaign were processed using a stochastic approach to establish the plant's mass and energy balances, which were then compared with operation of the plant with wood pellets. For this comparison, an extrapolation algorithm was developed to predict plant performance using bark dried to the same moisture content as wood pellets, ie, 8%w.b. Plant operation with bark feedstock was evaluated for operability, efficiency, and feedstock-related cost. The gas quality achieved during the test period was similar to that obtained for operation with wood pellets. Furthermore, no significant ash sintering or agglomeration problems were observed more than 750 hours of operation. The calculated biomass-to-biomethane efficiency is 43% to 47% (lower heating value basis) for operation with wet bark. However, the predicted biomass-to-biomethane efficiency can be increased to 55%–65% for operation with bark feedstock dried to 8% moisture content, with corresponding feedstock costs in the range of 24.2 to 32.7 EUR/MWh; ie, a cost reduction of about 40% compared with wood pellets.
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| 7. |
- Alamia, Alberto, 1984, et al.
(författare)
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Performance of large-scale biomass gasifiers in a biorefinery, a state-of-the-art reference
- 2017
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 41:14, s. 2001-2019
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Tidskriftsartikel (refereegranskat)abstract
- The Gothenburg Biomass Gasification plant (2015) is currently the largest plant in the world producing biomethane (20 MWbiomethane) from woody biomass. We present the experimental data from the first measurement campaign and evaluate the mass and energy balances of the gasification sections at the plant. Measures improving the efficiency including the use of additives (potassium and sulfur), high-temperature pre-heating of the inlet streams, improved insulation of the reactors, drying of the biomass and introduction of electricity as a heat source (power-to-gas) are investigated with simulations. The cold gas efficiency was calculated in 71.7%LHVdaf using dried biomass (8% moist). The gasifier reaches high fuel conversion, with char gasification of 54%, and the fraction of the volatiles is converted to methane of 34%mass. Because of the design, the heat losses are significant (5.2%LHVdaf), which affect the efficiency. The combination of potential improvements can increase the cold gas efficiency to 83.5%LHVdaf, which is technically feasible in a commercial plant. The experience gained from the Gothenburg Biomass Gasification plant reveals the strong potential biomass gasification at large scale.
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| 8. |
- Andersson, Viktor, 1983, et al.
(författare)
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Integration of algae-based biofuel production with an oil refinery: Energy and carbon footprint assessment
- 2020
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 44:13, s. 10860-10877
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Tidskriftsartikel (refereegranskat)abstract
- Biofuel production from algae feedstock has become a topic of interest in the recent decades since algae biomass cultivation is feasible in aquaculture and does therefore not compete with use of arable land. In the present work, hydrothermal liquefaction of both microalgae and macroalgae is evaluated for biofuel production and compared with transesterifying lipids extracted from microalgae as a benchmark process. The focus of the evaluation is on both the energy and carbon footprint performance of the processes. In addition, integration of the processes with an oil refinery has been assessed with regard to heat and material integration. It is shown that there are several potential benefits of co-locating an algae-based biorefinery at an oil refinery site and that the use of macroalgae as feedstock is more beneficial than the use of microalgae from a system energy performance perspective. Macroalgae-based hydrothermal liquefaction achieves the highest system energy efficiency of 38.6%, but has the lowest yield of liquid fuel (22.5 MJ per 100 MJalgae) with a substantial amount of solid biochar produced (28.0 MJ per 100 MJalgae). Microalgae-based hydrothermal liquefaction achieves the highest liquid biofuel yield (54.1 MJ per 100 MJalgae), achieving a system efficiency of 30.6%. Macro-algae-based hydrothermal liquefaction achieves the highest CO2 reduction potential, leading to savings of 24.5 resp 92 kt CO2eq/year for the two future energy market scenarios considered, assuming a constant feedstock supply rate of 100 MW algae, generating 184.5, 177.1 and 229.6 GWhbiochar/year, respectively. Heat integration with the oil refinery is only possible to a limited extent for the hydrothermal liquefaction process routes, whereas the lipid extraction process can benefit to a larger extent from heat integration due to the lower temperature level of the process heat demand.
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| 9. |
- Arjmand, Mehdi, et al.
(författare)
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Exergetic efficiency of high-temperature-lift chemical heat pump (CHP) based on CaO/CO2 and CaO/H2O working pairs
- 2013
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Ingår i: International Journal of Energy Research. - : Wiley-Blackwell. - 0363-907X .- 1099-114X. ; 37:9, s. 1122-1131
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Tidskriftsartikel (refereegranskat)abstract
- The use of reversible chemical reactions in recuperation of heat has gained significant interest due to higher magnitude of reaction heat compared to that of the latent or sensible heat. To implement chemical reactions for upgrading heat, a chemical heat pump (CHP) may be used. A CHP uses a reversible chemical reaction where the forward and the reverse reactions take place at two different temperatures, thus allowing heat to be upgraded or degraded depending on the mode of operation. In this work, an exergetic efficiency model for a CHP operating in the temperature-level amplification mode has been developed. The first law and the exergetic efficiencies are compared for two working pairs, namely, CaO/CO2 and CaO/H2O for high-temperature high-lift CHPs. The exergetic efficiency increases for both working pairs with increase in task, TH, decrease in heat source, TM, and increase in condenser, TL, temperatures. It is also observed that the difference in reaction enthalpies and specific heats of the involving reactants affects the extent of increase or decrease in the exergetic efficiency of the CHP operating for temperature-level amplification.
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| 10. |
- Axelsson, Erik Marcus Kristian, 1974, et al.
(författare)
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Profitability and off-site CO2-emission reduction from energy savings in the pulp and paper industry in different future energy markets
- 2012
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 1099-114X .- 0363-907X. ; 36:9, s. 975-986
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies by the authors have shown that energy savings in pulp and paper mills offer opportunities forincreased electricity production on-site or wood fuel export. The energy export implies reductions in CO2 emissions off-site, where fossil fuel or fossil-fuel-based electricity is replaced. To assess this potential and the related profitability for a future situation, four energy market scenarios were used. For a typical Scandinavian mill, the potential for CO2-emission reductions was 15–140 kton year-1 depending on the scenario and the form of energy export. Extrapolated to all relevant mills in Sweden, the potential was 0.4–3.1 Mton year-1, which is in the order of percent of the Swedish CO2 emissions. Wood fuel export implies larger reduction in CO2 emissions in most scenarios. In contrast, electricity export showed better economy in most of the cases studied; with annual earnings of 5–6Mh, this is an economically robust option. In the market pulp mill investigated, the wood fuel export was in the form of lignin. Lignin could possibly be valued as oil, regarding both price and potential for CO2-emissionreduction, making lignin separation an option with good profitability and large reductions of CO2 emissions.
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